Download booklet of abstracts

The Annual Swiss Conference on Ecology, Evolution, Systematics,
Biogeography and Conservation
10-12th of February 2016
University of Lausanne
Table of content
Organizing and scientific committees
p. 1
Plenary presentations
p. 2
Oral presentations
p. 3-40
Flash talks
p. 41-51
Posters
p. 52-96
List of participants
p. 97-102
Partners and sponsors
p. 103
Organizing and scientific committees
The organizing committee of the BIOLOGY16 conference at the University of Lausanne are all members of the
Department of Ecology and Evolution, except one representative of the Conservation Society from the University of
Bern. It is headed by Antoine Guisan and the following people are involved at different levels in the organization:
Lead & coordination
Prof. Antoine Guisan
Administration & registrations
Lena Kolecek
Dr. Olivier Broennimann
Web site
Dr. Olivier Broennimann
Catering and social events
Julien Goebel
Pre-conference workshop
Dr. Isabelle Castro
Dr. Lucie Froissart
Public outreach
Dr. Tania Jenkins
Dr. Lucie Froissart
Dr. Madeleine Scriba
Chloé Larose
IT support
Patrick Moratal
Dr. Olivier Broennimann
Logistics talks & posters, sponsors
Dr. Daniel Scherrer
Dr. Jean-Yves Humbert
Rui Fernandes (twitter)
External communication
Prof. Patrick Fitze
Graphical line of logo and all posters
Mathieu Mancion (student at ERACOM), with
support from Edy Ceppi (UNICOM), Antoine
Guisan, Olivier Broennimann and the organizing
committee.
Scientific committee
Prof. Antoine Guisan (Dept. Ecology and Evolution, UNIL)
Prof. Patrick Fitze (Dept. Ecology and Evolution, UNIL)
Dr. Jean-Yves Humbert (Institute of Ecology and Evolution, UNIBE)
Dr. Daniel Scherrer (Dept. Ecology and Evolution, UNIL)
Dr. Olivier Broennimann (Dept. Ecology and Evolution, UNIL)
Dr. Isabelle Castro (Dept. Ecology and Evolution, UNIL)
Dr. Lucie Froissart (Dept. Ecology and Evolution, UNIL)
Dr. Tania Jenkins (Dept. Ecology and Evolution, UNIL)
Rui Fernandes (Dept. Ecology and Evolution, UNIL)
Julien Goebel (Dept. Ecology and Evolution, UNIL)
Chloé Larose (Dept. Ecology and Evolution, UNIL)
1
Plenary presentations
PLENARY TALK 1
Evolution of reproductive modes in animals
Tanja Schwander, [email protected], University of Lausanne, Switzerland
PLENARY TALK 2
Linking patterns and process across scale: A case study with South American hummingbirds
Catherine Graham, [email protected], Stony Brook University, USA
PLENARY TALK 3
From biodiversity research and conservation biology to restoration ecology and ecosystem engineering
Raphaël Arlettaz, [email protected], University of Bern, Switzerland
PLENARY TALK 4
How do plants make a living? The predictability of plant life histories and population performance
Yvonne Buckley, [email protected], Trinity College Dublin, Ireland
1
Oral presentations
2
Distribution and biogeography of Gammarus lacustris in the Alps with eminent implications for
conservation strategies
Roman Alther, [email protected], eawag, Swiss Federal Institute of Aquatic Science and Technology,
Department of Aquatic Ecology; Florian Altermatt, [email protected], eawag, Swiss Federal Institute of
Aquatic Science and Technology, Department of Aquatic Ecology; Cene Fišer, [email protected], Department of
Biology, Biotechnical Faculty, University of Ljubljana
Amphipods are keystone species in many freshwater ecosystems. Knowing and understanding their distribution
and diversity is crucial to ensure and preserve freshwater ecosystem functioning, particularly in the northern
hemisphere. For the European Alps in general, and Switzerland in particular, only limited information on
amphipods has been available until recently. We studied the diversity and distribution of all 29 amphipod species in
Switzerland. Here we specifically focused on the lacustrine species Gammarus lacustris and analyzed its
distribution, biogeography as well as genetic and morphological differentiation. Based on mitochondrial DNA (COI
and 12S) and morphometric measurements, we show that the alpine individuals are highly divergent from all
circumboreal Gammarus lacustris. On the other hand studied populations of G. lacustris were genetically
surprisingly homogenous throughout the Alps. Furthermore we found a distinct distributional gap in the central
Alps in Switzerland, separating this amphipod species into two independent geographical groups. The occurrence
pattern within the Alps can be explained by a founder effect due to a Pliocene range expansion and vicariance due
to climate warming following the Quarternary glaciation. Historical drainage divides suggest a single recolonization
route from a distinct southern refugium. While G. lacustris is widely distributed in general and not endangered at a
global scale, the divergent and disconnected alpine clade is endemic to the European Alps and its habitat is
negatively affected by eutrophication, non-native species and possibly climate change.
Understanding the effect of warming temperatures on spring phenology of trees in the Alps using data
from a citizen science program
Daphné Asse, [email protected], University of Lausanne; Christophe Randin, [email protected],
University of Lausanne
Mountain regions are particularly exposed to climate change and temperature in the Alps increased two times
faster than the northern hemisphere during the 20th century. As an immediate response, spring phenological
phases of plant species such as budburst tend to occur earlier.
In 2004, the CREA (Centre de Recherches sur les Ecosystèmes d’Altitude, Chamonix, France) initiated the citizen
science program Phenoclim, which aims at assessing the long-term effects of climate changes on plant phenology
over the entire French Alps. Sixty sites with phenological observations were equipped with temperature stations
across a large elevational gradient.
We first used phenological records for five tree species (birch, ash, hazel, spruce and larch) combined with
temperature measurements to demonstrate that data collected by non-scientific observers provide consistent and
robust results for basic research. We then tested the effects of geographic and topo-climatic factors on the timing
of spring phenological phases. Finally, we tested the hypothesis that a lack of chilling requirement under warming
temperatures prevents the dormancy to be fully released and thus can delay spring phenological phases.
We found that growing degree-days was the best predictor of the timing of spring phenological phases, with only a
marginal contribution of solar radiation and no differences between regions of the French Alps. Our results also
suggest that spring phenological phases were delayed at low elevation by a lack of chilling during warm years.
With our results, we were able to show that a citizen science program can deliver useful data for basic phenological
research. Used retrospectively and with space-for-time substitution, our dataset provided insights about the future
impact of climate change on tree species. Such data will further be used to calibrate process-based phenological
models.
3
Measuring demographic parameters of Ophraella communa (Coleoptera: Chrysomelidae), a potential
biological control agent of Ambrosia artemisiifolia in Europe
Benno Augustinus, [email protected], CABI Europe-Switzerland
Ambrosia artemisiifolia, common ragweed is a noxious weed originating from Northern America. Additional to the
impact on agriculture, the weed produces highly allergenic pollen, which has a detrimental effect on human
wellbeing. Mechanical and chemical management have been elaborated, but they remain restricted to crop fields
and thus cannot prevent its further spread.
Ophraella communa (Coleoptera: Chrysomelidae), a beetle native to North America, is used very successfully as a
biological control agent in Japan and China. The beetle was found in Europe for the first time in 2013 in Northern
Italy. To investigate the beetle’s spread, population buildup and target impact, I will develop a climate-based
demographic model for O. communa, which will later be coupled with a ragweed population model.
For the insect model, I investigate the influence of temperature and relative humidity (RH) on survival and
developmental time along an altitudinal gradient in Northern Italy using cages and artificially transferred ragweed
plants. Generation time differed between sites, but not longevity of adults, indicating that temperature and RH
mainly impact immature life stages. All field cages were detected by wild populations of O. communa, even if the
next confirmed A. artemisiifolia population was up to ten kilometres away, indicating high dispersal and hostfinding ability of the beetle.
Additional to further population build-up experiments, future experiments will investigate overwinter survival and
dispersal behaviour of O. communa. Furthermore impact and host range experiments will be conducted with
Epiblema strenuana (Lepidoptera: Tortricidae), another potential biological control agent of common ragweed that
was first found in Israel in 2008.
No Accumulation of Transposable Elements in Asexual Arthropods
Jens Bast, [email protected], University of Lausanne; Ina Schaefer, [email protected], University of Göttigen; Tanja
Schwander, [email protected], University of Lausanne; Mark Maraun, [email protected], University of Göttigen;
Stefan Scheu, [email protected], University of Göttigen; Ken Kraaijeveld, [email protected], Universtiy of
Amsterdam
In the absence of recombination, deleterious transposable elements (TEs) can accumulate as a consequence of a
reduced efficacy of selection. This process is well documented for non-recombining genome portions of sexual
species, like Y-chromosomes, and occurs rapidly. A similar enrichment of TEs is expected for asexually reproducing
species, given their entire genome is non-recombining. We tested this prediction by comparing genomic TE content
of five asexual arthropod lineages and their sexual relatives, including crustaceans (Daphnia water fleas), insects
(Leptopilina wasps) and chelicerates (oribatid mites). The asexual lineages further vary in age, allowing to contrast
TE loads in “old” versus “young” asexuals. Surprisingly, there was no evidence for increased TE load in genomes of
asexual as compared to sexual lineages, neither for all classes of repetitive elements combined, or specific TE
families. Our study therefore suggests that TEs are unlikely to drive decay or extinction of extant asexual lineages
and that genome-wide lack of recombination generates different TE dynamics than lack of recombination in
isolated genome portions.
There are three mutually non-exclusive explanations for why asexual lineages do not harbor more TEs than sexual
lineages. First, molecular mechanisms underlying genome regulation in asexuals could hamper TE activity. Second,
asexual lineages may only arise from sexual ancestors with particularly low TE loads. And third, the differences in TE
dynamics might stem from selection for benign TEs in asexual lineages because of the lack of genetic conflict
between TEs and their hosts.
4
Including human attitude in habitat suitability models for the wolf in Switzerland
Dominik Behr, [email protected], University of Zurich; Gabriele Cozzi, [email protected], University
of Zurich; Arpat Ozgul, [email protected], University of Zurich
Large carnivores are recovering in most parts of Europe. In Switzerland, the gray wolf has naturally started to
return since 1995. But long-term survival of wolf populations depends heavily on human attitude. To determine
whether there are areas of suitable wolf habitat and positive human attitude in Switzerland, we modeled a
geographic map of human attitude and compared it with an existing habitat model of the wolf. The geographic
model of human attitude was calibrated with 3142 responses, which were collected using a written questionnaire.
In addition, we investigated which perceptions and sociodemographical factors determine human attitude towards
the wolf. The results suggest that acceptance of the wolf was mainly influenced by the perception of how harmful
the wolf is. Human attitude was mostly positive in the Central Plateau and Jura Mountains of Switzerland. In the
Alps however, attitude was predominantly negative in the west and inhomogeneous in the east. The Jura
Mountains and eastern Alps represented areas with highest potential for future wolf recolonization of Switzerland
as they offered both, a suitable wolf habitat as well as an environment of positive human attitude towards the
wolf. Net suitable wolf habitat varied strongly with simulated changes in human attitude. Therefore a monitoring
program is needed in Switzerland for both, wolf expansion and human attitude towards the wolf. The combination
of habitat suitability models with geographic models of human attitude provides a critical tool for proactive wolf
management as it closes the gap of habitat models, which lack human attitude.
Do parasites affect the cognitive performance of their fish hosts?
Sandra Binning, [email protected], University of Neuchatel; Redouan Bshary, [email protected],
University of Neuchatel; Dominique Roche, [email protected], University of Neuchatel; Alexandra
Grutter, [email protected], University of Queensland
Pathogens such as viruses, bacteria and parasites can impair host performance. However, some studies have found
positive relationships between infection status and cognitive performance suggesting that the overall impact of
pathogens on hosts is unclear. How does exposure to pathogens affect host cognitive abilities in natural fish
populations? To answer this question, we focused on cleaning mutualisms on the Great Barrier Reef, Australia:
many coral reef fishes routinely have ectoparasites removed from their surfaces by the cleaner wrasse (Labroides
dimidiatus). For the past 12 years, cleaner wrasse densities have been experimentally manipulated across a series
of patch reefs surrounding Lizard Island, allowing us to test the long-term consequences of parasite infection of
host cognition in wild fish populations. Using the ambon damselfish, Pomacentrus amboinensis, as a model, we
tested whether chronic and acute exposure to ectoparasites affects the performance of hosts in a series of
ecologically-relevant cognitive tasks (spatial recognition, reversal learning, visual discrimination). We also tested
whether eliciting a non-pathogenic immune response affects fish cognitive performance similar to parasitic
infection. We found that damselfish from patches without cleaners performed worse in visual discrimination tasks
than conspecifics from patches with access to cleaners. Similar results were obtained when fish were
experimentally exposed to parasites over several weeks suggesting that parasite infection explains differences in
observed performance. Interestingly, we found no differences in the performance of fish injected with an immune
stimulating agent (lipopolysaccharide) compared to sham-injected individuals suggesting that cognitive impairment
is not directly linked to immune activation. Our results highlight the importance of cleaner wrasse in promoting the
health of their client fish, and also shed light on the long and short-term consequences of parasites on their hosts’
cognitive abilities.
5
The stasis that wasn't: Adaptive evolution goes against phenotypic selection in a wild rodent
population
Timothée Bonnet, [email protected], University of Zurich; Erik Postma, [email protected],
University of Zurich
Natural and sexual selection almost universally favour larger individuals, and body size is typically highly heritable.
Nevertheless, while species tend to get larger over geological timescales, conclusive evidence of a contemporary
evolutionary response to selection remains elusive for wild animal populations for body size or any other fitnessrelated quantitative trait for that matter. Here we apply a comprehensive analytical framework to long-term
individual-based data from a wild rodent population, showing that despite phenotypic selection for being heavier,
animals have evolved to become lighter, and that this change is adaptive. We show the positive selection on mass
to be driven by a non-heritable trait related to both mass and fitness, while the evolutionary change toward smaller
individuals is an adaptive response to viability selection occurring during ontogeny. This response is associated with
a climatic shift which reduced the length of the snow-free season. While we show that models based solely on
estimates of phenotypic selection may thus be overly simplistic and not predictive of the rate and direction of
evolution, natural populations can show a rapid and adaptive but easily missed evolutionary response. Therefore,
contemporary adaptive evolution may be more common than is often believed.
Habitat fragmentation shapes the woodlarks habitat use via the distribution of its arthropod prey
Laura Bosco, [email protected], University of Bern; Alain Jacot, [email protected], University of
Bern, Swiss Ornithological Institute; Raphael Arlettaz, [email protected], University of Bern, Swiss
Ornithological Institute; Veronika Braunisch, [email protected], University of Bern
Vineyards in Switzerland are among the most intensively managed crop systems where up to 90% of all parcels do
not have any ground vegetation cover. However, there has been a considerable reduction in the application of
herbicides over the past decades, leading to more vegetation of higher diversity on the ground. These different
management types lead to a fragmented and almost binary system of few parcels with ground vegetation and lots
of parcels with bare ground. The woodlark (Lullula arborea) is an endangered ground-nesting bird species that
occurs in vineyards and during the breeding season mainly feeds on arthropods. Here, we investigated whether
fragmentation negatively affects arthropod abundance and diversity using a combination of pitfall traps and sweep
netting sampled using a 2x2 factorial design, by combining the two factors fragmentation and habitat amount
(low/high fragmentation x low/high habitat amount). In a second part we studied the habitat use of woodlarks
using radio-telemetry with respect to arthropod abundance and fragmentation effects. Our findings indicate that
fragmentation directly impedes the movement of arthropod prey, as in areas with higher connectivity and habitat
amount the abundance and richness of arthropods increased. As a consequence the woodlark adjusts its habitat
use in relation to the availability and abundance of its prey by using less fragmented areas more intensively. Using
these findings, our project aims to give clear recommendations to winegrowers about the amount, distribution and
connectivity of parcels with ground vegetation within the vineyards, which should ultimately favour biodiversity in
general and woodlarks in particular.
6
Influence of sexual selection and predation on two linked threshold traits in the black scavenger fly
Sepsis thoracica
Juan Pablo Busso, [email protected], University of Zürich; Wolf U. Blanckenhorn,
[email protected], University of Zürich
Polyphenic development is thought to play an important role in the evolution of phenotypic diversity and
morphological novelties. Polyphenisms are extreme cases of adaptive phenotypic plasticity and can evolve when a
linked underlying continuous trait presents a threshold above and below which the polyphenic trait expresses
alternative morphs. We analyzed the effect of sexual selection and predation on two linked threshold traits in
Sepsis thoracica (Diptera: Sepsidae), a black scavenger fly that presents a sigmoid relationship between body size
and coloration resulting in two condition dependent male morphs: Obsidian (small and black individuals) and
Amber (larger and yellow individuals). Competitive matings between the two morphs evinced that sexual selection
affects differently the phenotype of the two morphs, selecting for larger obsidian males but showing selection on
amber individuals. A similar result was obtained in predation experiments with three different predators (jumping
spider, dung fly, a bug). The predation vulnerability of the obsidians was inversely related to their body size, while
there was no relationship between these variables for the amber individuals. From comparisons between
latitudinal European populations we observe that populations with stronger selection also show a larger threshold
size, but no corresponding variation in the slope of the threshold. Therefore, evolutionary changes in a threshold
trait can be driven by varying the strength of selection in only one of the morphs. Differential intraspecific selection
pressures on dimorphic characters could thus equally contribute to the evolution of reproductive isolation,
ultimately leading to sympatric speciation.
Factors influencing species richness in the most speciose group of vertebrates: Teleostei
Lucie Cauwet, [email protected], University of Geneva; Juan Montoya, [email protected], University
of Geneva
Teleost fishes, with over 32,000 species, are impressively diverse, while presenting both very species rich and
species poor taxa. The mechanisms involved in creating such disparity may include a wide array of factors that are
often not independent of the lineages evolutionary history. The growing amount of available data and the
improvement of comparative methods give an opportunity to investigate the underlying and possibly intricate
causes driving species richness variation, while taking phylogeny into account.
In our study, we investigated the contribution of six explanatory variables on species richness in teleost fishes using
PGLS, i.e. mean body length, trophic level, marine or freshwater environment, reproductive behaviors, genome size
and taxa age.
The best model explained about 20% of the variance but several other models fitted to the data almost equally
well. To decipher the importance of the explanatory variables across all competing models, we performed a model
averaging analysis. This analysis indicated that mean body length had the strongest predictor weight on species
richness, to which it was negatively correlated. Trophic level, environment and taxa age had intermediate relative
importance while reproductive behaviors and genome size were the least informative.
Mean length explicative power could be explained by the fact that this variable is potentially correlated with many
other traits that could themselves play an important role in shaping patterns of species richness, such as dispersal
abilities, home range, density of population or generation time.
7
Modeling the evolution of recombination in sex chromosomes
Elisa Cavoto, [email protected], Department of Ecology and Evolution, University of Lausanne; Samuel
Neuenschwander, [email protected], Vital-IT, Swiss Institute of Bioinformatics, University of
Lausanne; Jérôme Goudet, [email protected], Department of Ecology and Evolution, University of Lausanne;
Nicolas Perrin, [email protected], Department of Ecology and Evolution, University of Lausanne
Sex chromosomes in vertebrates appear today either highly differentiated (with a degenerate chromosome in the
heterogametic sex) or cytologically identical. The former case is a consequence of complete arrest of
recombination in the heterogametic sex, while in the latter case occasional recombination can occur. Two
processes affect recombination during the evolution of sex chromosomes: the emergence of a sexually antagonistic
trait and the accumulation of deleterious mutations. Using individual based simulations, we investigate how the
interaction of these two processes affects recombination. In a finite sexual population, we vary the strength of
selection on a sexually antagonistic trait and the genetic load due to deleterious mutations, and track the evolution
of recombination.
We find that when the sexually antagonistic effect is strong, recombination is heavily (but not entirely) repressed in
males, independently of the genetic load, while in the absence of the sexually antagonistic trait, sex chromosomes
recombine freely. Surprisingly, the transition between these two opposite states is not gradual, and always occurs
for a specific strength of sexually antagonistic selection, largely independent of how many and how deleterious the
mutations are.
Our model predicts occasional recombination in males even when sexually antagonistic selection is maximal.
Occasional recombination likely contributes to the sex-chromosome homomorphy documented in many coldblooded vertebrates. Highly differentiated sex chromosomes (found e.g. in birds or mammals) can only evolve if
recombination in the heterogametic sex is entirely arrested, which likely involves other mechanisms (e.g. inversions
rather than recombination modifiers).
Evolutionary Insights from European bat trypanosomes
Laura Clément, [email protected], University of Lausanne; Bonny Laura, laura.bonny@unilch, University of
Lausanne; Genzoni Eléonore, [email protected], University of Lausanne; Christe Philippe,
[email protected], University of Lausanne
Despite Chagas disease being one of the most important human health problem in South America, the origin and
evolutionary history of the protozoan parasite Trypanosoma cruzi causing the disease, is still controversial. Because
of the predominantly South American and Australians distribution of the T. cruzi clade, it was commonly assume
that this parasite originated from terrestrial mammals, possibly Marsupials of the new world. However new
findings indicate that T. cruzi was originally a bat parasite that switched several time on terrestrial mammals in
both the new and the old world.
In Europe studies of trypanosomes infecting bats are almost non-existent and their distribution remains vastly
unknown. In this study, we characterized trypanosome isolates from 893 individuals out of 24 bat species and
sampled across a large geographical range in Europe. We highlight the presence of trypanosomes in 21 species,
with a mean prevalence of 28%. No apparent phenotypic effect of infection in any of the species sampled have
been noticed.
Genetic data and phylogenetic analyses using 18S rRNA gene revealed three Trypanosoma species infecting
European bats, all within the T. cruzi clade.
Co-phylogenetic analysis between bats and their associated trypanosomes show a high genus specificity. Moreover
higher haplotype diversity within Trypanosoma was found in European bats compared to their South-American
relatives. In addition, a new haplotype of trypanosome, probably a new species never described in Europe and
restricted to the Miniopterus bat genus, was discovered. Surprisingly this new haplotype was genetically closely
related to an African trypanosome species recently described and phylogenetically located to the root of the T.
cruzi clade. Our findings shed new light into the presumed “new world” origin of Trypanosoma cruzi and further
suggest that bats have played an important role on the diversification and the origin of the parasite causing Chagas
disease.
8
Testing for a role of avian malaria on bird speciation
Camille-Sophie Cozzarolo, [email protected], University of Lausanne; Tania Jenkins,
[email protected], University of Lausanne; Alan Brelsford, [email protected], University of California
Riverside; Philippe Christe, [email protected], University of Lausanne
Parasites may play a role in speeding up speciation, for example by causing disruptive selection. It is however not
yet clear to what extent. There is evidence that avian malaria parasites exert a negative effect on bird fitness.
Hybrid zones make interesting natural laboratories for the study of the processes underlying speciation. Tension
zones are a type of hybrid zone, the narrowness of which is maintained by a balance between dispersal and
selection against the hybrids. One such tension zone involves the two yellow-rumped warbler (Dendroica coronata)
subspecies, D.c. coronata and D.c. auduboni, which interbreed in the Canadian Rockies. Brelsford and Irwin (2009)
showed that there was a partial reproduction isolation between coronata and auduboni, and rejected assortative
mating in the parental subspecies, suggesting the existence a postzygotic selection against hybrids. Here, we test
whether avian malaria parasites could play a role in selecting against hybrids of coronata and auduboni. If this is the
case, we predict that hybrids may inherit specialist parasites from both parental species, and may be subject to
outbreeding depression regarding genes involved in resistance against malaria parasites. Hence, we expect hybrids
to have a higher prevalence of malaria infection and a higher diversity of malaria parasites lineages. We screened
747 individuals from Alberta and British Columbia for Plasmodium, Haemoproteus and Leucocytozoon parasites.
We found that hybrids did not have a higher malaria prevalence, but instead had a lower of intermediate
prevalence. There is no significant difference in the diversity of malaria lineages between the warbler subspecies,
three lineages being very abundant in both parental subspecies and hybrids. In conclusion, it seems that there is no
specificity of avian malaria parasites in yellow-rumped warbler subspecies. It is therefore not likely that avian
malaria parasites are linked to a higher selection pressure against hybrids.
Cost of exposure to Plasmodium parasite in the mosquito vector Culex pipiens
Jessica Delhaye, [email protected], University of Lausanne; Laura Bonny, [email protected], University of
Lausanne; Philippe Christe, [email protected], University of Lausanne; Olivier Glaizot, [email protected],
Museum of Zoology, Lausanne
Parasites of vector-borne diseases may affect vector’s life history traits through direct energy diversion and/or
immune system activation. Both processes are energetically costly for the vector, which has to differentially
reallocate its resources to ensure its reproduction and/or survival. Until now, studies have focused on the effect of
infection on vector’s life history traits. However, when vectors are exposed to a parasite, individuals may also
experience immune activation to clear the infection and are thus expected to pay a cost of immune response. We
investigated the effect of exposure to a parasite on vector’ life history traits using the natural Plasmodium relictum
– Culex pipiens association. We allowed female mosquitoes reared in the lab to feed on uninfected canaries
(control), on Plasmodium-infected canaries during the acute phase of infection (high parasitaemia) or during the
chronic phase (low parasitaemia). We recorded mosquitoes’ blood meal size, reproductive investment (oviposition
and clutch size) and survival. To measure immune activation, some females were sacrificed either at 5 or 15 days
post feeding for gene expression quantification. Because we were interested in the cost of resistance, successfully
infected females were discarded from our analyses. We found that unexposed females were more likely to oviposit
than exposed females and that the oviposition probability of exposed females decreased with increasing exposure
level. Clutch size increased with blood meal size and for similar blood meal size Plasmodium-exposed females laid
more eggs compared to unexposed females. In contrast, we found no effect of exposure on survival. We expect
(ongoing laboratory analyses) that the observed reduced oviposition probability is correlated with immune
activation level in exposed females. These results suggest a cost of resistance as uninfected exposed individuals
have reduced oviposition probability. Moreover, the higher blood-to-egg conversion in exposed females suggests a
potential trade-off between reproduction and survival.
9
Does pre-dispersal predation influence seed packaging strategies and seed viability?
Lucía DeSoto, [email protected], University of Coimbra; David Tutor, [email protected], University of
Valladolid; Rubén Torices, [email protected], University of Lausanne and Estación Experimental de Zonas
Áridas (EEZA-CSIC); Susana Rodríguez-Echeverría, [email protected], University of Coimbra; Cristina Nabais,
[email protected], University of Coimbra
An increased understanding of intraspecific seed packaging (i.e. seed size/number strategy) variation across
different environments may improve current knowledge of the ecological forces that drive seed evolution in plants.
In particular, pre-dispersal seed predation may influence seed packaging strategies, triggering a reduction of the
resources allocated to undamaged seeds within the preyed fruits. Assessing plant reactions to pre-dispersal seed
predation is crucial to a better understanding of predation effects, but the response of plants to arthropod attacks
remains unexplored.
We evaluated the effect of cone predation by two arthropods, Trisetacus sp and Megastigmus sp., on the size and
viability of undamaged seeds in populations of the multi-seeded fruited conifer Juniperus thurifera L.
(Cupressaceae) with contrasting seed packaging strategies, namely, North African populations with single-largeseeded cones and South European populations with multi-small-seeded cones.
The incidence of predation was lower on the single-large-seeded African cones than on the multi- small-seeded
European ones. Seeds from non-preyed cones were larger and had a higher germination success than uneaten
seeds from preyed cones, but only in populations with multi-seeded cones and in cones attacked by Trisetacus sp.,
suggesting a differential plastic response to predation. Pre-dispersal seed predation might have been a strong
selective pressure in European populations with high cone predation rates, being a process that maintains multismall-seeded cones and empty seeds as a strategy to save some seeds from predation. Conversely, pre-dispersal
predation might not have a strong effect in the African populations with single-large-seeded cones characterised by
seed germination and filling rates higher than those in the European populations.
Our results indicates that differences in pre-dispersal seed predators and predation levels may affect both selection
on and intraspecific variation in seed packaging.
Effect of biogeographic history on population vulnerability in European amphibians
Christophe Dufresnes, [email protected], University of Lausanne
The genetic diversity of populations, which contributes greatly to their adaptive potential, is negatively affected by
anthropogenic habitat fragmentation and destruction. However, continental-scale losses of genetic diversity also
resulted from the population expansions that followed the end of the last glaciation, an element that is rarely
considered in a conservation context. We addressed this issue in a meta-analysis in which we compared the spatial
patterns of vulnerability of 18 widespread European amphibians in light of phylogeographic histories (glacial refugia
and postglacial routes) and anthropogenic disturbances. Conservation statuses significantly worsened with
distances from refugia, particularly in the context of industrial agriculture; human population density also had a
negative effect. These findings suggest that features associated with the loss of genetic diversity in post-glacial
amphibian populations (such as enhanced fixation load or depressed adaptive potential) may increase their
susceptibility to current threats (e.g., habitat fragmentation and pesticide use). We propose that the
phylogeographic status of populations (i.e., refugial vs. post-glacial) should be considered in conservation
assessments for regional and national red lists.
10
Migratory passerines infected with avian malaria cross the Mediterranean Sea later and travel with
higher leucocyte counts than uninfected conspecifics
Tamara Emmenegger, [email protected], Swiss Ornithological Institute; Susanne B. Müller;
Lukas Jenni, [email protected], Swiss Ornithological Institute; Fernando Spina, [email protected],
Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA); Silke Bauer, [email protected], Swiss
Ornithological Institute
Dealing with the consequences of infectious diseases is one of several challenges migrants face on their move.
When on migration, energetic resources are particularly critical and their allocation can affect the organism’s
performance. Depending on the mechanism of how migrants can deal with infections and compensate for elevated
energy demand, we expected infected and uninfected individuals to differ in arrival date or body condition after
crossing the Mediterranean Sea in spring.
We aimed at (1) linking the seasonal pattern of arrival at a stopover site to individual infections with malariaparasites and (2) developing a mechanistic concept for the parasite host interaction by including different factors
describing body condition, immune response and life history stage.
We could identify a clear seasonal pattern with infected birds arriving later in the season than uninfected
individuals. Infected birds also carried higher leucocyte (white blood cells) loads than uninfected individuals,
indicating that malaria infections caused a strong immune response. Thus, a mechanistic explanation of differential
arrival in infected and uninfected birds might be that infected bird cannot fully compensate for elevated energy
expenditure of immune response and must spent this at the costs of resources for endurance flight. The temporal
separation of infected from uninfected individuals has also implications for the dynamics of infections within a
population and its geographic spread.
Reproductive tactics and sperm competition in the Seba's short tailed bat, Carollia perspicillata
Nicolas Fasel, [email protected], University of Bern; Charlotte Wesseling, [email protected],
University of Neuchâtel; Magali Meniri, [email protected], University of Neuchâtel; Verena Saladin,
[email protected], University of Bern; Fabrice Helfenstein, [email protected], University of
Neuchâtel; Heinz Richner, [email protected], University of Bern
When the investment for a privileged access to mates is costly, alternative reproductive tactics (ARTs) may pay off.
However, while sneaking copulations may reduce pre-copulatory costs, it exposes males to sperm competition and
therefore should require higher fertilization efficiency. In order to study the link between ARTs and sperm
competition, we analyzed various reproductive traits in the Seba's short tailed bat (Carollia perspicillata). In this
species, harem males secure a privileged access to females, in contrast with peripheral and bachelor males, who
sneak copulations. With social observations collected over three years, we used a multistate model to describe the
social status transitions, in relation with age. Then, we estimated the reproductive success for each social status
and further analyzed the sperm quality from males of different social status. We finally controlled for the expected
difference in the copulation rate by collecting a second ejaculate after a three-days sexual abstinence. Our results
showed that ARTs in C. perspicillata were plastic and reversible in a sequential manner. Harem males had only
more offspring during younger and older ages, but when males of all social status showed a peak in their
reproductive success, this difference disappeared. Sneaker males showed a higher sperm quality with spermatozoa
swimming faster and living longer. However, after three days of sexual abstinence, sperm quality was similar
among social status. This suggests that the higher copulation rate of harem males may reduce their sperm quality
and offer a chance to sneaker males to sire offspring.
11
Interactive effects of mycorrhizal inoculation and jasmonic acid endogenous production on plant
resistance against herbivores
Ludovico Formenti, [email protected], University of Neuchâtel; Sergio Rasmann,
[email protected], University of Neuchâtel
Mycorrhizal fungi, in addition to improve plant performance via increased food acquisition, they have also been
shown to increase plant resistance against herbivores, but little is known how endogenous plant defences and
mycorrhizal defence enhancement interact with each other in the presence of herbivores. With this study, we
asked whether the increased plant resistance conferred by the mycorrhizal symbiosis can synergistically interact
with the jasmonic acid (JA) phytohormonal pathway of the plant responsible for orchestrating plant defence
strategy against chewing herbivores.
To measure the interactive effects of mycorrhizal inoculation and JA-mediated defences, we measured resistance
against S.littoralis larvae and plant defensive traits of wild-type tomato plants and two mutants lines; a JA-knockout
mutant, and a mutant which overexpresses JA, in the presence or absence of mycorrhizal fungi.
According to predictions, we observed that plant defensive traits such as the number of trichomes and specific leaf
area were higher in WT plants and plants that overexpress JA, compared to plants impaired in JA production.
Additionally, both wild-type plants, enhanced JA-producing plants, and mycorrhizal inoculation reduced S.littoralis
survival and biomass, but their effects were not additives. Instead, the positive effects of mycorrhizal inoculation
on plant resistance weakened with increasing JA production.
In sum, both JA production and mycorrhizal inoculation increase plant resistance, but do not synergistically interact
for multiplying resistance. Instead, we suggest that the magnitude of resistance conferred by mycorrhizal fungi can
substitute the lack of defences in plants impaired in the JA phytohormonal pathway.
Informed dispersal in metacommunities
Emanuel Fronhofer, [email protected], eawag: Swiss Federal Institute of Aquatic Science and
Technology & University of Zurich; Jan Klecka, [email protected], Biology Centre of the Czech Academy of
Sciences; Tabea Kropf, [email protected], ETH Zurich; Carlos Melian, [email protected], eawag: Swiss
Federal Institute of Aquatic Science and Technology; Florian Altermatt, [email protected], eawag: Swiss
Federal Institute of Aquatic Science and Technology & University of Zurich
Dispersal, and the underlying movement behaviour, are processes of pivotal importance for understanding and
predicting metapopulation and metacommunity dynamics. Generally, dispersal decisions are non-random and rely
on information, such as the presence of conspecifics. However, studies on metacommunities that include
interspecific interactions generally disregard information use. Therefore, it remains unclear whether and how
dispersal in metacommunities is informed and whether rules derived from single-species contexts can be scaled up
to (meta-)communities.
Firstly, using microcosm experiments with the ciliate model organism Tetrahymena we present evidence for the
shape of the density-dependent dispersal and movement function in a single-species setting. Movement strategies
in Tetrahymena were plastic and density-dependent. The observed movement reaction norm was u-shaped which
is likely due to an Allee effect. This adaptive density-dependent movement strategy was mediated by chemical
cues.
Secondly, using experimental protist metacommunities, we show how dispersal and movement are informed and
adjusted by the strength of inter-specific interactions. We found that predicting informed movement and dispersal
in metacommunities requires knowledge on behavioural responses to intra- and inter-specific interaction strength.
Consequently, metacommunity dynamics inferred directly from single-species metapopulations without taking
inter-specific interactions into account are likely flawed. Our work identifies the significance of information use for
understanding metacommunity dynamics, stability and the coexistence and distribution of species.
12
Feathers and bones as a temporal archive to study lead exposure and stress events in golden eagles –
potential and constraints
Kathrin Ganz, [email protected], University of Zürich
Lead acts as a nonspecific poison affecting all body systems and belongs to the most commonly found heavy metals
in ecosystems. There are several cases of sub-lethal and lethal lead poisoning reported in golden eagles from the
Swiss Alps and it is thought that poisoning mainly happens through the ingestion of carcasses or offal from game
shot with lead ammunition. However, how often and over which period such an uptake of lead takes place is not
yet resolved.
During growth, feathers incorporate lead and corticosterone, the main avian stress hormone, and thus represent a
temporal archive of these substances. Therefore, lead and corticosterone concentration in feather segments of
golden eagles were measured as they offer the possibility to infer the frequency and magnitude of lead uptake and
the release of corticosterone during feather moult. Additionally, lead in bones was measured to determine lifetime
exposure to this heavy metal. Although lead exposure in bones was considerable, pointing at repeated lead uptake,
almost no elevated lead values were found in feathers, suggesting that lead uptake through ingestion of offal from
lead shot game and moult happen at two different times. Because in this study lead values differed widely between
bones, doubts arose, whether bones can be substituted for one another in comparative lead studies, as is generally
assumed.
13
Combining modelling and genetic approaches in conservation: application to the genus
Capurodendron Aubrév. (Sapotaceae) in Madagascar
Rhéa Garratt, [email protected], Conservatoire et Jardin botaniques de la Ville de Genève et Université de
Genève, 1292 Chambésy, Switzerland; Yamama Naciri, [email protected], Conservatoire et Jardin
botaniques de la Ville de Genève et Université de Genève, 1292 Chambésy, Switzerland; Anthony Lehmann,
[email protected], enviroSPACE, Environmental Sciences Institute, Carl-Vogt 66, 1211 Geneva 4,
Switzerland; Sven Buerki, [email protected], Department of Life Sciences, Natural History Museum, Cromwell
Road, London SW7 5BD, United Kingdom; Martin Callmander, [email protected], Conservatoire et Jardin
botaniques de la Ville de Genève et Université de Genève, 1292 Chambésy, Switzerland; Laurent Gautier,
[email protected], Conservatoire et Jardin botaniques de la Ville de Genève et Université de Genève, 1292
Chambésy, Switzerland
Madagascar is a known biodiversity hotspot, with a high endemism rate and threat level, and gaps still exist in the
knowledge of its flora. Moreover, the Malagasy species and their habitats are under great threat, mainly because of
human activities. Their conservation is therefore one of the greatest challenges that we are faced with. To achieve
a more accurate definition of areas with high conservation priorities, we apply a multidisciplinary approach to the
plant endemic genus Capurodendron (Sapotaceae), combining species modelling, phylogenetic inferences and
IUCN threat Categories.
Capurodendron includes twenty to thirty species of slow-growing trees, which are primarily found in primary
forests. The conservation of species of this genus is challenging since local communities widely used it as timber,
therefore impacting the sustainability of natural populations.
Madagascar plants are overall undercollected and the current available herbaria collections of the genus do not
provide sufficient distributional data. A modelling based on known occurrences and environmental data was
therefore conducted to produce potential species distribution maps. IUCN threat Categories could thus be assigned
to each species using two parameters derived from each map: extent of occurrence (area of the smallest polygon
containing all known occurrences of a taxon) and area of occupancy (sum of the surface of all pixels at a given
resolution where there are occurrences).
To take into account the species’ evolutionary history and the weight of each of them in the choice for priority
areas, chloroplast and nuclear genes were sequenced and used to build a species tree under the Multi-Species
Coalescent. The phylogenetic diversity contained in targeted areas was computed and helped defining priority
areas.
This comprehensive approach is an attempt to find new ways to evaluate species threat levels when very few data
is available and to define areas on which a conservation emphasis should be put, considering species’ distribution
and phylogenetic diversity parameters."
14
Identifying the genetic basis of longevity after 30 years of artificial selection in Drosophila
Kathrin Garschall, [email protected], University of Lausanne; Daniel K. Fabian, [email protected],
University of Cambridge; Gonçalo Santos Matos, [email protected], Gulbenkian Institute of Science,
Portugal; Martin Kapun, [email protected], University of Lausanne; Bruno Lemaitre, [email protected],
École polytechnique fédérale de Lausanne; Robert Arking, [email protected], Wayne State
University; Christian Schlötterer, [email protected], Vetmeduni Vienna; Thomas Flatt,
[email protected], University of Lausanne
Despite much progress in understanding the molecular determinants of aging and lifespan, the role of naturally
occurring polymorphisms underlying the evolution of longevity traits remain poorly understood. Here, we have
analyzed the genetic basis of longevity in Drosophila melanogaster by combining whole-genome next-generation
sequencing with phenotyping experiments in a set of longevity selection and control lines initiated by Leo Luckinbill
and Bob Arking in the early 1980s. Using population genetic and statistical tools, we have identified candidate
genes and single nucleotide polymorphisms (SNPs) whose patterns of differentiation have most likely been shaped
by selection. Interestingly, we find strong evidence for a functional enrichment of immunity genes, particularly
those involved in Toll signaling. To test whether this pattern is functionally relevant and likely to be causative, we
assayed survival of selected and control flies upon challenge with a fungal, bacterial (gram positive and gram
negative) and a viral pathogen. Long-lived lines survived all pathogenic infections significantly better than the
controls, with the difference in survival – depending on the pathogen – increasing with age. The dynamics of
bacterial clearance did not differ between selected and control lines, suggesting that the increased immune
function of long-lived selected flies is caused by improved tolerance to infection, not resistance. In further support
of the notion that the evolution of increased lifespan results in improved immunity, we found that selection and
control lines differ in their age-dependent patterns of gene expression for several immune genes and in the lifespan
response to a pharmacological inhibitor of NF-kB, a central transcription factor in immunity. Together, our results
provide strong evidence for the existence of a causal – but still poorly understood – relationship between the
evolution of longevity and improved immune function.
Male harassment leads to the promotion of sex when population density is high
Nina Gerber, [email protected], University of Zürich
Sex is considered paradoxical because of several known costs of sexual compared to asexual reproduction. One
example of such a cost of sexual lineages is sexual harassment by males. Harassment by males should at first sight
increase the relative advantage of asexual reproduction, as the cost of sex is increased. However, this statement
assumes that only sexual females suffer the costs of harassment. If males harass females irrespective of their type
and the competition of reproductive types occurs within a population, then parthenogenetic lineages might not
manage to escape the costs of harassment. In species with facultative sex the same females can perform either
sexual or asexual life cycles, and females trying to reproduce asexually may consequently be subject to male
harassment. If resisting male harassment is costly enough, it might be beneficial for a female to accept a mating
and undertake a sexual life cycle rather than to resist and undertake an asexual one. We investigate the effects of
sexual harassment on the maintenance under different population densities. Our model shows that low population
density leads to the complete extinction of males, and thus to the evolution of completely asexual populations. By
contrast, at high densities male harassment can lead to females no longer resisting male mating attempts and
sexual reproduction takes over. These results could also play a role in explaining patterns of geographic
parthenogenesis.
15
Evolution of brain ontogenetic growth under ecological challenges
Mauricio González-Forero, [email protected], University of Lausanne; Timm Faulwasser,
[email protected], EPFL; Laurent Lehmann, [email protected], University of Lausanne
Large brains use much energy but support skills (or cognitive abilities, knowledge, information, etc.) that allow
overcoming ecological and social challenges. However, the relative contribution of ecological and social factors to
large brain evolution is uncertain. We formulate a mathematical model to obtain predicted brain growth schedules
when individuals evolve facing ecological but no social challenges. The model yields predicted brain and body
masses throughout ontogeny and, when parameterized with modern human data, it recovers many human lifehistory attributes, including brain and body masses of late Homo erectus and Neanderthal scale. The model
identifies synergy among skills as a determinant cause for large encephalization. Additionally, the model shows that
a large brain is favored by intermediately challenging environments where skills are largely ineffective and
energetically expensive to maintain. These results support ecological, including cooking, hypotheses for human
brain evolution and suggest that despite the substantial social function of human brains, their large sizes can largely
result from their ecological function alone.
Spatial cascade in meta-ecosystems triggered by detritus flows: neighbors matter for local ecosystem
dynamics
Isabelle Gounand, [email protected], University of Zurich & eawag; Eric Harvey, [email protected],
University of Zurich & eawag; Pravin Ganesanandamoorthy, [email protected], eawag;
Florian Altermatt, [email protected], University of Zurich & eawag
Most spatial ecology focuses on effects of species dispersal on community dynamics and coexistence, but
ecosystems are often also strongly connected by flows of resources. We experimentally tested how neighboring
communities can indirectly affect each other’s dynamics via detritus exchanges. We used two-patch protist metaecosystems linked only by detritus flows. We manipulated community structure in one ecosystem by having one
bacterivorous species either alone, in competition with other protist species or in the presence of predators. We
manipulated community composition in the other ecosystem such that they consisted either of heterotroph or
autotroph species. We studied the effects of ecosystems’ reciprocal effects on community and ecosystem local
dynamics via detritus exchanges. We found that both community structure and composition influenced neighbor
dynamics. The communities connected to the autotroph species were doing better than with heterotrophic
neighbors (regardless of the quantity of detritus produced), to such an extent that coexistence in the competition
treatment was determined by the neighbor identity. In contrast, communities collapsed when connected to
ecosystems where a generalist predator was present. These neighbor effects were attributable to both changes in
the quality and the quantity of the resources at the basis of the food chain via detritus flows. Our results highlight
the importance of bi-directional indirect effects in connected ecosystems. These interdependencies should be
taken into account in ecosystem management since alterations to community structure and composition in one
ecosystem are likely to cascade over space onto other ecosystems, even if dispersal of species is completely absent.
16
Hope the grass is greener on the other side: evidence from experimental meta-ecosystem
Eric Harvey, [email protected], University of Zurich; Isabelle Gounand, [email protected],
University of Zurich; Pravin Ganesanandamoorthy, [email protected], eawag; Florian
Altermatt, [email protected], University of Zurich
Over the last decade extensive theoretical work has suggested that meta-ecosystem dynamics may have important
implications for the stability of biological communities and ecosystem processes. While this theoretical work has
been strongly motivated by empirical case-examples, experimental demonstrations of reciprocal effects from crossecosystem resource flows remain to be made. We used two-patch protist meta-ecosystems to simulate a
perturbation gradient affecting both ecosystems simultaneously and altering cross-ecosystem detritus exchanges.
We observed non-trivial temporal feedbacks between species demography and detritus spatial flows modulated by
perturbation intensity. We then characterized this relationship between perturbation intensity, species growth rate
and cross-ecosystem subsidies with a mathematical model. We show that meta-ecosystem dynamics have
implications for perturbed ecosystems because effects of perturbations can spatially cascade among connected
ecosystems via spatial flow modifications. These results call for a more integrative management of human-altered
landscapes that takes into account regional dynamics related to both species and resource flows.
Honey bees learn to ignore low quality dance information
Robbie I'Anson Price, [email protected], University of Lausanne; Christoph Grüter,
[email protected], University of Mainz
Animals are expected to use social learning strategically and rely on it only in circumstances when doing so
provides higher payoffs than individual learning or the use of private information. In accordance with this
prediction there is growing evidence for social learning strategies. It remains unclear, however, whether the
strategic use of social information is genetically encoded or whether animals learn about the value of social
information through experience. In the honey bee waggle dance a dancing bee provides vector information about
the location of high quality resources to nest-mates. Here we tested if honey bees can learn not to rely on this
communication signal if dance information is of low informational quality. We found that when exposed to
disoriented dances, i.e. dances that provide poor quality information for long time periods, 20% fewer bees
followed waggle dances and bees observed 25% fewer waggle runs compared to bees that were exposed to dances
offering reliable information. The reduction in dance following was accompanied by an increase in the number of
foragers leaving the colony. This indicates that bees that experienced unreliable dance information increase their
rate of individual exploration. We also found that colonies began to lose less weight in the disoriented treatment
compared to the oriented treatment once the number of foragers became higher. This suggests that a strategy that
relies less on social information is more effective in the temperate conditions we carried out our study in. Our
findings also suggest that bees can learn about the value of waggle dance information and adjust their use of social
information with reference to expected benefits. This represents a remarkable case of behavioural flexibility in the
context of a highly stereotyped communication behaviour.
17
Evidence of increased foraging efficiency in polydomous ant colonies
Patrick Joye, [email protected], University of Lausanne
The tremendous ecological success of eusocial insects is mainly based on their complex social organization,
allowing them to adapt to numerous environments. Many studies have highlighted the huge diversity that can be
found in eusocial insects when it comes to how they organize their colony. One particular variation of social
organization in ants is whether a single colony is spread over one (monodomy) or several nests (polydomy). Here,
we test whether polydomy affects foraging efficiency and try to understand what aspects of polydomy are
influencing foraging. We first tested the capacity of monodomous and polydomous colonies to gather food, and
measured the extra-nest activity of each colony. Next we tested if the increase in the foraging area brought by
polydomy is beneficial for the colony in terms of foraging speed.
Finally, we tested if food sources diversity and quality could influence nest choice when colonies were choosing
new nests. We found that polydomous colonies where more efficient, by having a higher food collecting rate, and
more active than monodomous ones. Also, it appeared that the presence of a nest close to a food source allowed
another further nest to faster exploit this food source. Finally, when emigrating, colonies did seem to choose their
nest according to the location of food sources of a better quality, or from a different type than the source that was
close to their previous nest. These results demonstrate an increased foraging efficiency of polydomous colonies.
Adaptive Evolution of In(3R)P, a clinal Inversion Polymorphism in Drosophila
Martin Kapun, [email protected], University of Lausanne; Chloé Schmidt, [email protected],
University of Lausanne; Esra Durmaz, [email protected], University of Lausanne; Jérome Goudet,
[email protected], University of Lausanne; Paul Schmidt, [email protected], University of
Pennsylvania; Thomas Flatt, [email protected], University of Lausanne
In(3R)P, a common cosmopolitan inversion in D. melanogaster, exhibits steep latitudinal clines across multiple
continents, but whether this pattern is due to spatially varying selection or demography remains unclear. To
address this fundamental question we first estimated inversion frequencies by applying diagnostic marker SNPs to
pool-seq data from 10 populations along the North American east coast and 29 populations from across Europe. By
comparing our estimates to published records we find that the inversion cline has remained stable for over thirty
years. Consistent with this cline being maintained by selection, comparisons between clinal patterns of In(3R)P and
neutrally evolving intronic SNPs suggest that this inversion evolves non-neutrally. In further support of an adaptive
scenario, SNP-wise regression reveals numerous inversion-associated alleles differentiated in parallel between the
North American and Australian clines. Second, we sequenced pools of isochromosomal lines of In(3R)P karyotypes
from the endpoints of the North American and European latitudinal cline and identify major inversion-specific
genetic differentiation among karyotypes. Finally, again paralleling observations from Australia, we find that
In(3R)P makes a major contribution to the well-known body size cline in North America. Together, these results
provide compelling evidence that In(3R)P is maintained by spatially varying selection across multiple continental
clines.
18
Ecological factors driving nematode communities and soil ecosystems functioning along elevational
gradients
Alan Kergunteuil, [email protected], Functional Ecology Laboratory (LEF) - Université de Neuchâtel Switzerland; Raquel Campos-Herrera, [email protected] , MeditBio - Universidade do Algarve - Portugal; Sara
Sanchez-Moreno, [email protected], Plant Protection Products Unit (DTEVPF) - INIA - Spain; Sergio Rasmann,
[email protected], Functional Ecology Laboratory (LEF) - Université de Neuchâtel – Switzerland
The question of what drives species range distribution and species interactions remains fundamental in ecology,
and elevational gradients are ideal tools for measuring changes in natural communities and the associated
ecological factors. Across world ecosystems, including mountain slopes, nematodes represent about four out of five
metazoic organisms. They play important roles in the soil foodwebs and are frequently considered as indicators of
major ecosystems functions. We therefore conducted a study on soil nematode biodiversity, and asked whether
and how elevation gradients shape nematode communities. Soil samples were collected along 5 transects that span
an average 2500 m elevational gradient. Over 30.000 nematodes belonging to 48 genera and 3 families were
identified and assigned to a trophic group. We found that although invertebrate species richness decreases with
elevation, the amount and diversity of nematode taxa increased, certainly due to biotic and abiotic factors (enemy
free-space, soil humidity). Among the three trophic groups for which the metabolic footprint increase with
elevation, the amount of carbon entering soil foodwebs through herbivourous nematodes raised by 70 % between
900m and 2500m. Thus, we were interested in understanding how plant diversity along mountain gradients could
affect nematode communities. Discriminant analyses of both plant and nematode diversity showed similar
patterns: soils ranging between 1500 and 2000m (subalpine) and those collected over 2000m (alpine) presented
specific communities of plants and nematodes. Plants distributed at high altitudes (e.g. Festuca violaceae, Salix
retusa, Viola calcarata) were associated with nematodes harboring life history traits that confer local adaptions to
harsh environments (e.g. Eudorylaimus spp., Pratylenchus spp., Paratylenchus spp.).
This study provides information about the main ecological drivers involved in the nematode taxa distribution along
elevational gradient. From ecological perspectives, the resulting changes in the composition of the nematode
communities shed light on how habitat modification affects ecosystems functioning.
19
Dorsos are green, Eyespots are blue, Does Natural Selection shape you?
Telma Laurentino, [email protected], Computational Biology and Population Genomics Group (CoBiG2),
Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa,
Portugal; Francisco Pina-Martins, [email protected], Computational Biology and Population Genomics
Group (CoBiG2), Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências,
Universidade de Lisboa, Portugal; Pedro Patrício, [email protected], Centre for Ecology, Evolution and
Environmental Changes (cE3c), Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa,
Portugal; Joana Fino, [email protected], Department of Human Genetics, National Institute of Health Dr
Ricardo Jorge, Lisbon, Portugal; Luís Ceríaco, [email protected], Museu Nacional de História Natural e da
Ciência (MUHNAC), Rua da Escola Politécnica 58 1250-102 Lisboa; Filipa Alves, [email protected],
Biophysics and Genetics of Morphogenesis Group, Instituto Gulbenkian de Ciência, Oeiras; Octávio S. Paulo,
[email protected], Computational Biology and Population Genomics Group (CoBiG2), Centre for Ecology, Evolution
and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa, Portugal
Timon lepidus is one of the species that endured the climatic cycles of the Quaternary, which greatly influenced
population evolutionary dynamics in the Iberian Peninsula. There are currently three described parapatric
subspecies, distributed along an ecological cline. Along this cline, differences in phenotype seem to be associated
with specific bioclimatic regions, leading to the hypothesis of ecological speciation.
Understanding speciation requires the integration of ecology, evolution and the role of history in shaping the
diversification or decline of lineages (a). We must understand both how variation in phenotype may affect the
fitness of individuals in their local environment, and how natural selection is shaping the genome of those
organisms.
Focused on populations of two of the described subspecies, we set to investigate the speciation continuum phase
in which these populations stand, looking for patterns of adaptation and natural selection signatures across the
genome of this lizard.
Resorting to NGS technology (RAD-seq), phenotypic and environmental data, we uncover the interplay of
evolutionary forces, neutral and non-neutral, shaping the adaptation of these populations, and discover an
unexpectedly strong pattern of local adaptation, which does not follow the currently described taxonomy.
Furthermore, cues for repeated adaptive evolution arise, opening exciting perspectives to the research on how
populations adapt to their environment.
Selection is thus shaping the evolutionary history of this lizard, which has one of the most beautiful European
reptile phenotypes.
(a) Reznick, D. N. & Ricklefs, R. E. Darwin’s bridge between microevolution and macroevolution. Nature 457, 837–
842 (2009).
20
Habitat heterogeneity favours asexual reproduction in natural populations of grassthrips
Guillaume Lavanchy, [email protected], University of Lausanne; Marie Strehler, [email protected],
University of Lausanne; Maria Noemi Llanos Roman, [email protected], University of Trujillo, Peru; Malie
Lessard-Therrien, [email protected], University of Bern; Jean-Yves Humbert, [email protected], University of Bern; Zoé Dumas, [email protected], University of Lausanne; Kirsten
Jalvingh, [email protected], University of Lausanne; Karim Ghali, [email protected], University of Lausanne;
Amaranta Fontcuberta, [email protected], University of Lausanne; Bart Zijlstra,
[email protected], University of Lausanne; Raphaël Arlettaz, [email protected], University of
Bern; Tanja Schwander, [email protected], University of Lausanne
Explaining the overwhelming success of sex among eukaryotes is difficult given the obvious costs of sex relative to
asexuality. Different approaches have shown that sex can provide benefits in spatially heterogeneous environments
under specific conditions, but whether spatial heterogeneity commonly contributes to the maintenance of sex in
natural populations remains unknown. We experimentally manipulated habitat heterogeneity for sexual and
asexual thrips lineages in natural populations and under semi-natural mesocosm conditions by varying the number
of hostplants available to these herbivorous insects. Asexual lineages rapidly replaced the sexual ones,
independently of the level of habitat heterogeneity in mesocosms. In natural populations, the success of sexual
thrips decreased with increasing habitat heterogeneity, with sexual thrips apparently only persisting in certain
types of hostplant communities. Our results illustrate how genetic diversity based mechanisms can favor asexuality
instead of sex when sexual lineages co-occur with genetically variable asexual lineages.
Can mate limitation select for parthenogenesis? A test in mayflies
Maud Liégeois, [email protected], University of Lausanne; Luca Sciuchetti, [email protected], University
of Lausanne; Michel Sartori, [email protected], Cantonal Museum of Zoology; Tanja Schwander,
[email protected], University of Lausanne
Different modes of reproduction are characterized by various costs and benefits, which often vary among different
ecological contexts. An obvious advantage of unisexual reproduction in parthenogenetic females is reproductive
insurance: individuals capable of parthenogenesis can produce offspring even if they fail to find a mating partner.
Accordingly, across populations, high levels of mate limitation are expected to coincide with strong selection for
unisexual reproduction. In order to test whether mate limitation can select for parthenogenesis, we used mayflies
as a model system. Mayflies are characterized by a very short adult life span (typically in the order of a few days),
which is expected to generate strong selection for reproductive insurance. We measured the capacity for
parthenogenesis, population sex ratios and densities (which should be correlated with the level of mate limitation)
of six mayfly species at 32 locations distributed across different rivers in Switzerland. Using these data, we identify
factors correlated with female-biased sex ratios and high rates of parthenogenesis in natural populations.
21
Recalibration, genotype calling and inference of genetic diversity from ancient genomes
Vivian Link, [email protected], University of Fribourg; Athanasios Kousathanas, [email protected],
University of Fribourg; Daniel Wegmann, [email protected], University of Fribourg
How did farming arrive in Europe? Ancient DNA can provide us with as valuable information about the past as
archeology. We are working on a method to estimate heterozygosity in ancient humans, which is a central
population genetics parameter for knowing about our past. The analysis of heterozygosity ancient DNA is
obstructed by Post-mortem damage (PMD) - a typical characteristic of ancient DNA: Due to it being exposed to the
elements for thousands of years, ancient DNA is very fragmented and contains deaminated cytosins, which after
sequencing appear as C-to-T mutations. When estimating heterozygosity on DNA in general, thinking about
sequencing error rates is crucial, since we want to avoid calling a wrongly sequenced base as an alternative allele.
There exist methods for the recalibration of the sequencing error rates estimated by the sequencing machine, such
as BQSR by GATK. However, BQSR does not take PMD into account and is thus not adapted for ancient DNA. We
developed a new pipeline for the recalibration in ancient DNA, thus providing quality scores of high reliability. In
addition, we developed improved genotype callers compared to the current state of the art. Due to the low
sequencing coverage of ancient genomes, most studies resort to calling haplotypes only. To address this, we
developed a computationally fast method to infer genetic diversity, measured as a local theta, as well as a Bayesian
approach to call allele presence using nucleotide frequencies and theta as a prior. Applying our methods to ancient
DNA from Greece and Anatolia demonstrate a direct genetic link between the early farmers of the Aegean and
those arriving in Europe a few thousand years later.
The influence of altered mowing regimes of lowland meadows on ground beetles (Coleoptera:
Carabidae) and rove beetles (Coleoptera: Staphylinidae)
Lukas Lischer, [email protected], University Bern; Raphaël Arlettaz, [email protected],
University Bern; Jean-Yves Humbert, [email protected], University Bern
Biodiversity-rich grasslands are highly threatened. On one hand more and more grasslands are converted into
arable lands, and on the other hand management of existing grasslands is severely intensified. These changes are
putting pressure on biodiversity including ground and rove beetles, as many of them are habitat specialists. The
aim of this study was to test the effect of four different mowing regimes on ground and rove beetles. The mowing
regimes were implemented in 2010 in existing extensively managed hay meadows (EMM) in 12 study regions (four
meadows per region) across the Swiss plateau: control regime (C-regime: BPA: EMM with first cut not before 15
June), delayed regime (D-regime: EMM, but first cut not before 15 July), 8 weeks (8W-regime: EMM, but maximum
two cuts per year and minimum 8 weeks between them) and refuge (R-regime: EMM, but with rotational uncut
refuge left on 10-20% of the meadow area when mown). Ground and rove beetles were sampled in 2015 by means
of pitfall traps. Results showed that the rove beetle abundance increased on C, R and 8W-regimes after mowing,
when compared to the uncut delayed mowing regime. The stenotopic and xerophilous ground beetles had a
significantly higher richness in the 8W- and R-regimes, when compared to the D-regime. The main conclusion is
that leaving an uncut refuge (R-regime) does not negatively affect ground and rove beetle populations and can be
recommended as it has been shown to favour other arthropod groups such as orthopterans, wild bees and
butterflies (previous studies in the same project).
22
Plant interaction networks' response to environmental changes
Gianalberto Losapio, [email protected], University of Zurich, Department of Evolutionary Biology and
Environmental Studies; Christian Schöb, [email protected], University of Zurich, Department of
Evolutionary Biology and Environmental Studies
Plant–plant interactions are fundamental processes for structuring plant communities and are an important
mechanism governing the response of plant species and communities to environmental changes. Thus,
understanding the role played by the network of interacting plant species in modulating the impact of
environmental changes on plant community composition is crucial. We aimed to assess the robustness of a plant–
plant interaction network to four environmental change scenarios, to evaluate the role played by facilitative
interactions and to assess the factors making species more likely to disappear. Using observational data and
simulations, we combined two approaches used in plant ecology and network theory, which have not been used
together previously. We recorded the abundance and functional traits (LDMC, LA and SLA) of plant species
associated with three foundation species (Arenaria tetraquetra spp. amabilis, Plantago holosteum and Festuca
indigesta) and growing alone in open areas in the high-elevation dry environment of the Sierra Nevada Mountains
(Spain). Using a functional trait-based criterion for species susceptibility in each environmental change scenario, we
simulated primary species loss and explored the robustness against secondary extinctions of others species. The
scenarios of increasing summer temperature and increasing drought showed the steepest decline in plant species
richness, while nitrogen enrichment produced the highest rate of species secondary extinctions. Rare beneficiary
species associated to P. holosteum were the most likely to get secondary extinct. Overall, foundation species
modulated the impact of environmental changes by increasing species survival thanks to the reduction of potential
secondary extinctions. This indicates that facilitation can buffer environmental impacts on plant communities by
stabilising plant–plant interaction networks.
Resolving the 'big-sperm paradox'
Stefan Lüpold, [email protected], University of Zurich; Scott Pitnick, [email protected], Syracuse University
According to theory, equal investment in offspring production among males and females should increase the
reproductive success of each sex to a similar degree with each additional mating. However, if males invest
substantially less than females, they can increase their fitness by multiple mating whereas female fitness may be
constrained. This disparity among sexes increases the variance in male reproductive success relative to that of
females, resulting in stronger sexual selection on males. This argument can also be made at the gamete level to
explain the evolution of anisogamy.
However, in fruit flies, a ""big-sperm paradox"" was recently discovered. In these flies, species producing extremely
long sperm (up to 20 times the male's body length) can produce only very few of them, thereby approaching
isogamy, lowering the variance in male fitness and weakening the intensity of sexual selection. This raises the
question of how sexual selection could possible drive the evolution of long sperm.
In my talk, I will discuss this big-sperm paradox and show that it can be resolved by linking the reproductive
potential and opportunity for sexual selection to condition dependence of sperm production in the light of the
sperm size-number trade-off. Our results suggest that sperm length and relative investment in sperm production
can be important indicators of sexual selection intensity similar to ornaments and armaments under premating
sexual selection. If our results also apply to other taxa without postmating parental investment, sperm size and
spermatogenic investment may provide simple and accurate assays for comparative analyses of the strength of
sexual selection in such systems.
23
A pharyngeal jaw evolutionary innovation facilitated extinction in Lake Victoria cichlids
Matthew McGee, [email protected], eawag; Samuel Borstein, [email protected], UT Knoxville; Russell
Neches, [email protected], UC Davis; Ole Seehausen, [email protected], eawag; Peter Wainwright,
[email protected], UC Davis
Evolutionary innovations, traits that give species access to previously unoccupied niches, may promote speciation
and adaptive radiation. Here, we show that such innovations can also result in competitive inferiority and
extinction. We present evidence that the modified pharyngeal jaws of cichlid fishes and several marine fish
lineages, a classic example of evolutionary innovation, are not universally beneficial traits. A large-scale analysis of
dietary evolution across marine fish lineages reveals that the innovation compromises access to energy-rich
predator niches. We show that this competitive inferiority shaped the adaptive radiation of cichlids in Lake
Tanganyika and played a pivotal and previously unrecognized role in the mass extinction of cichlid fishes in Lake
Victoria after Nile perch invasion.
(This manuscript appeared in the Nov 27 issue of Science.)
Ancient hybridization fuels cichlid fish adaptive radiation
Joana Meier, [email protected], eawag & University of Bern; Ole Seehausen, [email protected],
eawag & University of Bern; Laurent Excoffier, [email protected], University of Bern; David Marques,
[email protected], eawag & University of Bern; Catherine Wagner, [email protected], University of
Wyoming
The haplochromine cichlid fishes of Africa’s Lake Victoria region are the fastest known vertebrate adaptive
radiation, including more than 700 species. Adaptive radiations in different lakes within this region, each with tens
to hundreds of endemic species, make up this “Lake Victoria Region Superflock”, wherein species display an
enormous diversity of ecologies and phenotypes. Yet, all of these species have evolved in only 100,000-200,000
years. How this diversity of species and ecological functions could evolve on such rapid timescales is an enduring
question. Using genomic data from riverine haplochromine cichlids sampled from all major African drainage
systems, and representative species from all lineages within the Lake Victoria region, we show that the superflock
evolved from a hybrid swarm. All lake radiations show very similar proportions of mixed ancestry derived from two
distantly related haplochromine lineages that evolved in isolation from one another in different river systems for
more than a million years before hybridizing in the Lake Victoria region. We show how this admixture event
facilitated subsequent adaptive radiation by providing genetic variation that has been recombined and sorted into
many new species. Variants that were fixed between the parental lineages show accentuated differentiation
between young Lake Victoria species, but appear in new combinations. Notably, each of the two major allele
classes of an opsin gene involved in adaptation and speciation in Lake Victoria cichlids is found exclusively in one of
the two parental lineages, suggesting that the variation at this gene segregating in the LVRS derives from
hybridization between these lineages. Our results suggest that hybridization between relatively distantly related
species, when coincident with ecological opportunity, may facilitate rapid adaptive radiation. Thus, hybridization,
even in the distant past, may have important implications for the origins of present day biodiversity.
24
Interaction between two invasive organisms on the European chestnut: does the chestnut blight
fungus benefit from the presence of the gall wasp?
Joana Beatrice Meyer, [email protected], Swiss Federal Research Institute WSL; Laure Gallien,
[email protected], Swiss Federal Research Institute WSL; Simone Prospero, [email protected], Swiss
Federal Research Institute WSL
The impact of invasive fungal pathogens and pests on trees is often studied individually, thereby omitting possible
interactions. In this study the ecological interaction between the chestnut blight fungus Cryphonectria parasitica
and the chestnut gall wasp Dryocosmus kuriphilus was investigated. We determined if abandoned galls could be
colonized by C. parasitica and thereby act as an entry point and a source of pathogen inoculum. Moreover we
assessed the identity and diversity of other gall-colonizing fungal species. A total of 1973 galls were randomly
sampled from 200 chestnut trees in eight Swiss stands. In a stand C. parasitica was isolated from 0.4–19.2% of the
galls. The incidence of C. parasitica on the galls and the fungal diversity significantly increased with the residence
time of D. kuriphilus in a stand. All but one C. parasitica cultures were virulent. The predominant fungus isolated
from galls was Gnomoniopsis castanea whose abundance influenced negatively that of C. parasitica. This study
shows that D. kuriphilus galls can be colonized by virulent strains of the chestnut blight fungus C. parasitica. This
can have effects on the chestnut blight incidence even in chestnut stands where the disease is successfully
controlled by hypovirulence. The gall wasp presence influences also the fungal species composition on chestnut
trees.
Investigating the onset of adaptive radiation 50 years after the invasion of a new adaptive zone
Florian N. Moser, [email protected], University of Berne & eawag; Jacco C. Van Rijssel,
[email protected], University of Berne & eawag; Ole Seehausen, [email protected], University of
Berne & eawag
The East African haplochromine cichlids provide one of the global diversity hotspots with up to 2000 species. Most
of this diversity is thought to have arisen through adaptive radiation within individual lakes. Recent studies
revealed lake depth, energy and sexual dimorphism as important predictors for cichlid diversity. Both natural and
sexual selection have been suggested to operate along depth gradients and to be important in speciation
processes. Lake Chala, a deep, tropical clear-water lake, meets, since the arrival of the sexually dimorphic
haplochromine cichlid Astatotilapia sp. in the 1970s, all the prerequisites for the onset of a new adaptive radiation.
We quantified phenotypic and genotypic diversity and divergence in this haplochromine cichlid community 45
years after invasion of Lake Chala and created fitness landscapes with growth rate as a fitness proxy to investigate
the selection regime. Further we compared those findings to the diversity and divergence of a sister species pair of
the Lake Victoria radiation, Pundamilia pundamilia and P. nyererei, which occurs at different stages of reproductive
isolation at different sites in Lake Victoria.
After less than 50 years divergence time in Lake Chala, we found similar phenotypic diversity within Astatotilapia
sp. as in Pundamilia spp. in Lake Victoria after approximately 15’000 years of divergence. Further, we found
significant disruptive selection acting on Astatotilapia sp. in Lake Chala, whereas similar selection between
Pundamilia spp. was only found at the deepest and clearest of the four Lake Vicoria study sites, where reproductive
isolation is strongest.
In summary these results indicate that the Astatotilapia sp. of Lake Chala are under disruptive selection and
reached phenotypic diversity sufficient to initiate incipient speciation within 50 years, thus making them an ideal
system to investigate the onset of adaptive radiations.
25
Diverse influences of bacteria on the water flea Daphnia magna
Alexandra Mushegian, [email protected], University of Basel; Dieter Ebert, [email protected],
University of Basel
All animals evolved in a world dominated by bacteria. Animal evolution has featured widespread adaptation to the
presence of bacteria as well as associations with bacteria that enable adaptations to diverse environments. In a
series of experiments using the aquatic crustacean Daphnia magna and its bacterial microbiota, we have identified
several different benefits of symbiosis. Bacteria have a positive influence on embryonic development at elevated
temperature and enable growth on a plant-based diet. Additionally, environmental bacteria appear to have a
general positive influence on Daphnia health. We speculate that the constant exposure to bacteria in aquatic
environments has led Daphnia and possibly other aquatic organisms to function optimally in the presence of
bacteria.
Limiting low temperatures for plant growth – a comparative experimental approach using cold
adapted alpine plants and winter crops
Sebastian Nagelmüller, [email protected], University of Basel; Achim Walter,
[email protected], ETH Zurich; Christian Körner, [email protected], University of Basel
Temperature is a major factor regulating growth and the geographical range of plants. In particular, low
temperatures are known to be important for growth and productivity in arctic- alpine plants and winter crops.
Therefore understanding growth constraints at low temperature can be used to explain species distribution limits
in arctic alpine environments and reveal breeding-related genotypic differences among winter crop cultivars.
Under the hypothesis that all cold adapted higher plants face similar thermal limitations for growth, we aimed to
identify the absolute low temperature limits and thresholds for growth in alpine species and winter crops.
Particularly, we were interested in the dynamics of plant growth limited by low temperatures under natural field
conditions.
Two experimental field platforms were developed to measure growth with high precision at regular frequency. One
was used to measure root growth responses to temperature in alpine plants and the second for monitoring leaf
elongation rates of winter cereals.
We found that plant growth is limited below 5 °C and asymptotically approaches zero. An absolute limit for tissue
expansion was observed short above 0 °C, for both, alpine root length increment and leaf elongation rates in winter
cereals. Given the reduced growth rate below 5 °C, temperatures above this threshold are essential for plants to
establish sufficient above and below ground biomass.
However, the sensitivity of growth to low temperature was species- and genotype-specific with a tradeoff between
increased growth at low temperature (<5) and decreased growth at higher temperature (>5) and vice versa. Our
results confirm previous studies and underline the critical role of temperature on plant growth and development.
Particularly, the immediate effect of changing temperatures is shown by the temporal resolution of the data.
26
Defence mechanisms against pathogenic fungi in the ambrosia beetle Xyleborinus saxesenii: evidence
for social immunity in cooperative beetles
Jon Andreja Nuotclà, [email protected], Universität Bern, Division of Behavioural Ecology, Bern; Michael
Taborsky, [email protected], Universität Bern, Division of Behavioural Ecology, Bern; Peter
Biedermann, [email protected], Max Planck Institut für Chemische Ökologie, Jena
The success of social insect colonies often depends on their ability to cope with a variety of pathogens. Apart from
immune responses of individuals this may involve also a ‘social immune defence’ consisting of different social
behaviours suited to reduce pathogen prevalence. This ‘social immune system’ is especially important in fungusfarming species, because the microclimate conducive to the proliferation of cultivated fungi usually promotes the
growth of competing fungi and pathogens. Ambrosia beetles, which are fungus-farming bark beetles, exhibit a
variety of social organizations ranging from solitary breeding to eusociality. This makes them ideal models to study
the ultimate and proximate mechanisms of colony hygiene and social immune defences in complex insect societies.
Our main study species, the fruit-tree pinhole borer Xyleborinus saxesenii is a fungus farming ambrosia beetle
exhibiting cooperative breeding. It lives in colonies founded by a single fertilised female in the heartwood of freshly
dead trees. Females delay their dispersal to help raising siblings by grooming them and tending the fungus garden.
Our data show that females are actively up-regulating hygienic behaviours like allogrooming, selfgrooming and
cannibalism of apparently infected larvae when experimentally exposed to pathogenic microorganisms. Such social
immune responses were not yet known in cooperatively breeding beetles. We also found that the beetles react
towards malicious micro-organisms by dispersing earlier from the nest, and that dispersing females are attracted to
volatiles released by their mutualistic fungus and by ethanol. Ethanol is known to generally attract ambrosia
beetles due to its prevailing presence in weakened and rotting trees. Cues emitted by fungus gardens of
successfully breeding conspecifics may be a strong indicator of the productivity of the fungus and for the wood's
suitability as breeding medium. Such information is probably of great importance to the beetles before they choose
a tree for colony foundation, because this is a ‘once in a lifetime’ event.
Global warming disrupts biodiversity-ecosystem functioning relationships
Elodie Parain, [email protected], University of Fribourg; Rudolf Rohr, [email protected], University of
Fribourg; Sarah Gray, [email protected], University of Fribourg; Louis-Félix Bersier, [email protected], University of Fribourg
High species biodiversity is crucial to maintain a high ecosystem functioning. This so-called biodiversity-ecosystem
functioning (BEF) relationship has been demonstrated to occur in a broad range of ecosystem. However, the effects
of global warming on this relationship have never been explored. In this study, we developed a BEF theory based
on mechanistic population dynamic models. Our new theory propagates the effect of global warming on the BEF
relationship, and predicts that temperature increase will intensify competition and consequently flatten or even
disrupt the relationship. We confirmed these predictions by conducting a laboratory experiment with natural
microbial microcosms. Our results unravel a significant threat of global warming, as diversity alone may not be
sufficient for enabling high ecosystem functioning.
27
Conservation Genomics of Swiss honeybees, Apis mellifera ssp., reveals specific Swiss ecotype and
calls for improved management efforts
Melanie Parejo, [email protected], Institute of Bee Health, Vetsuisse Faculty, University of Bern,
3003 Bern, Switzerland and Agroscope, Swiss Bee Research Centre, 3003 Bern, Switzerland; David Wragg,
[email protected], Institut National de la Recherche Agronomique, GenPhySE, 31326 Castanet-Tolosan,
France; Laurent Gauthier, [email protected], Agroscope, Swiss Bee Research Centre, 3003
Bern, Switzerland; Peter Neumann, [email protected], Agroscope, Swiss Bee Research Centre,
3003 Bern, Switzerland and Institute of Bee Health, Vetsuisse Faculty, University of Bern, 3003 Bern, Switzerland;
Markus Neuditschko, [email protected], Agroscope, Swiss National Stud Farm, 1580
Avenches, Switzerland
The genetic integrity of the native honeybee subspecies of Northern Europe, Apis mellifera mellifera, is threatened
by introduced subspecies from evolutionary distant lineages in most of its range. To counteract introgression,
conservation areas for this subspecies have been established within Europe (e.g. in Switzerland and France).
The aims of this study are to characterize the current Swiss honeybee population structure, to quantify the degree
of admixture in native populations and to compare Swiss and French conservatories regarding their effectiveness to
preserve the native gene pool.
We sequenced whole genomes of 120 drones sampled throughout Switzerland (87 apiaries), including 39 samples
from 4 conservation areas and compared them to 31 samples from a conservatory in the French Alps. After
mapping and variant calling according to best practices, we identified >3Mio SNPs with an individual depth of
coverage of 10X.
Although average admixture levels are 2.4 times lower in the Swiss conservatories compared to the French one,
there are some highly admixed individuals in the Swiss population, suggesting that the management efforts are still
not able to entirely purge all foreign alleles. Nonetheless, a large part of the native A. m. mellifera population in
Switzerland was found to be genetically pure and diverse. Moreover, the Swiss A. m. mellifera clusters separately
from the French one suggesting a specific local ecotype.
The data support to continue and even improve the efforts to maintain the specific Swiss A. m. mellifera ecotype
and its high genetic diversity. Due to the known genotype-by–environment interactions and the benefits of genetic
diversity, conservation efforts appear to be even more important nowadays to buffer these precious pollinators
against multiple drivers such as pesticides, parasites and pathogens.
28
Niche innerness, a population based metric measuring the ecological proximity to the niche margins
Blaise Petitpierre, [email protected], Université de Lausanne; Olivier Broennimann,
[email protected], Université de Lausanne; Antoine Guisan, [email protected], Université de
Lausanne
Environmental niche modeling (ENM) depicts species niche by relating species occurrences to environmental
variables. They have been shown to provide highly valuable insights to reconstruct the ecology or the evolutionary
history of species distributions. However, ENM relates to the global niche of species and are more difficult to apply
at the population level. A metric that depicts the position of specific populations in regards to the species niche
margin is still needed to reveal the potential of adaptation, dispersal, speciation or fitness. Here, we propose such a
metric that we call the niche innerness.
On the contrary to traditional ENM methods based on the niche centroid, the innerness measures the
environmental proximity between a population and the closest species niche margin. Niche margins have been
shown to be crucial in adaptive mechanisms and in the definition of ecological or evolutionary niche shifts. Our
framework includes a randomization test to detect signal of niche conservatism within populations, taking into
account two important factors in niche dynamic: environmental availability in the study area and species niche
breadth.
We illustrate this original framework using the well-known introductions of Centaurea stoebe in North America, an
invasive plant affected by a niche shift resulting from evolutionary and ecological phenomena. We use the niche
innerness to answer the three following questions:
1) Do the first introductions belong to the native niche ?
2) Which native populations are the most marginal ?
3) Do the two different cytotypes (diploids and tetraploids) share the same niche?
These three questions exemplify a wide range of problems concerning many evolutionary biologists, ecologists and
biogeographers.
Interspecific hybridization during density-dependent range expansion: consequences in evolution and
conservation
Claudio S. Quilodrán, [email protected], University of Geneva; Béatrice Nussberger,
[email protected], University of Zurich; Mathias Currat, [email protected], University of
Geneva; Juan I. Montoya-Burgos, [email protected], University of Geneva
The dynamics of range expansion needs to be taken into account when studying the genetic consequences of an
invasive species spreading and interbreeding with native populations. This is also critical when interbreeding results
from shifts in the natural distribution of species due to climate change. Among the species interactions that take
place during range expansions, hybridization is of growing concern in both conservation and evolutionary biology.
Models aimed at studying the genetic consequences of species range expansion have been recently developed but
usually assume that dispersal is independent from local population densities. However, organisms may disperse
because they are attracted by conspecifics, or to the contrary, because they prefer depopulated areas. These
behaviours are referred to as positive or negative migratory responses toward conspecifics. Here, through spatially
explicit simulations, we assess the effects of various forms of density-dependent dispersal during range expansion
on the genetic introgression between two interacting species. We show that massive introgression of neutral genes
in the invasive species occurs in all the density-dependent dispersal models (positive and negative), even when
hybridization is relatively low. For a given hybridization rate the levels of introgression are lower when dispersal is
negatively related to local densities and higher under positive density-dependent dispersal. Our results suggest that
invasive organisms that tend to disperse due to conspecific attraction and local species that avoid them are more
affected by genetic introgression. We applied our theoretical framework on a real case of hybridization between
European wildcat and domestic cat in Switzerland. We highlight that considering density-dependent dispersal has
the potential to improve the predictive power derived from models of species range expansion.
29
Biodiversity promoting areas in agricultural landscapes: the importance of area, quality and
connectivity for bird and butterfly biodiversity
Eva Ritschard, [email protected], University of Bern; Silvia Zingg, [email protected], University of
Bern; Jean-Yves Humbert, [email protected], University of Bern; Raphaël Arlettaz,
[email protected], University of Bern
Since the second half of the 20th century, European farmland biodiversity is facing serious declines due to
agricultural intensification. To counteract this decline in Switzerland, subsidized biodiversity promoting areas
(BPAs), such as extensively managed meadows, wildflower-strips, hedgerows and traditional high-stem orchards,
were implemented in 1993 by government. Yet, evaluation studies have shown that their beneficial effects on
biodiversity are only modest and that decline is persisting, even though a lot of financial resources are invested
every year. Missing connectivity between BPAs, or/and poor ecological quality of the individual BPA, are often used
as arguments to explain the lack of effectiveness of these schemes. In this study we investigated the influence of
the BPAs on bird and butterfly species richness in 46 Swiss lowland agricultural landscapes of 1 km2. Our results
indicate that BPAs affect bird and butterflies differently. We found a positive effect of % of BPA area (ha of BPAs
over total ha of utilized agricultural area) on overall bird species richness, whereas farmland and red-list bird
species were influenced by BPA quality, rather than % of BPA area. Butterfly species richness (overall and
farmland), did as well reacted positively to % of BPA area in the landscape. The sample size of red-list butterfly
species was too small to observe an effect. On the other hand, no evidence was found, that BPA quality has an
effect on butterfly species richness. In addition and contrary to common predictions, there was no evidence that
connectivity (mean distance between BPAs) has an effect on bird or butterfly species richness. There is an urgent
need to define and implement effective conservation measures if we want to stop the loss of biodiversity in
agricultural landscapes. This study will help decision makers to allocate BPA financial resources in the most
effective way.
Proximate mechanisms underlying variation in cooperation levels by the cleaner fish Labroides
dimidiatus
Domnique Roche, [email protected], Université de Neuchâtel; Maiwenn Jornod,
[email protected], Université de Neuchâtel; Alexandra Grutter, [email protected], University of
Queensland; Redouan Bshary, [email protected], Université de Neuchâtel
Game theoretic models help us understand how and when cooperation can evolve and persist. However, current
models fall short of explaining the striking amount of variation in cooperation levels that we observe in nature. For
example, there is ample qualitative evidence that supply and demand determine the exchange value of goods or
services traded between cooperating partners (‘biological market theory’). However, different species or
individuals with similar partner choice options can be treated differently by the same partner. This is the case in the
mutualism between the cleaner wrasse, Labroides dimidiatus, and its ‘client’ reef fishes. In this system, cleaners
sometimes cheat and remove live tissue instead of ectoparasites. Client fishes differ not only in the number of
cleaners they can visit, but also in a suite of other traits. To evaluate the relative importance of traits that might
influence cleaning service quality, we examined 13 non-predatory client species and assessed: home range size
(proxy for partner choice options), fast start performance and turning rate (proxies for punishing ability), parasite
load, and mucus properties (proxies for client value and/or temptation to cheat). We explored how these traits
relate to cleaning service quality measured as the occurrence of cheating events in nature. Six variables were
equally important in explaining variation in cooperation levels: duration of the interaction, client size, amount and
caloric content of mucus, gnathiid ectoparasite load, client turning rate and partner choice options. Partner choice
is the cornerstone of biological market theory, but was only one of many different variables that regulate service
quality in this marine mutualism. Our results suggest that future modelling efforts should integrate concepts such
as temptation to cooperate/defect, partner choice options and punishment ability to better explain natural
variation in cooperative behaviour.
30
Multiple origins of reversals in sexual size dimorphism and sexual selection in black scavenger flies
Patrick Rohner, [email protected], University of Zurich; Wolf U. Blanckenhorn,
[email protected], University of Zurich; Nalini Puniamoorthy, [email protected], Syracuse University
Sexual size dimorphism (SSD) arises when the net effects of natural and sexual selection on body size equilibrate
differently in males and females. Species and populations can exhibit quantitative variation in the extent of SSD but
directional reversals in SSD within species are rare in the animal kingdom. Here we report the results of a microand macroevolutionary approach to studying SSD in a family of black scavenger flies. First, we studied geographic
SSD variation in three widespread and closely related species using common garden experiments and found stark
variation between and within species. Specifically, Sepsis biflexuosa is monomorphic across Europe (EU) and North
America (NA) and S. cynipsea (found only in EU) exhibits female-biased SSD. Interestingly, the sister species S.
neocynipsea to the latter displays contrasting SSD in EU (females larger) and NA (males larger) (This pattern is
opposite to the geographic reversal in SSD of S. punctum documented in a previous study). We estimated selection
on adult body size under three increasingly male-biased operational sex ratios in S. neocynipsea and found that the
intensity of sexual selection on male size varied between continents but fecundity selection on female body size did
not vary, in accordance with the differential equilibrium model for the evolution of SSD. Next, we conducted
comparative analyses of 49 taxa and document at least six independent origins of male-biased SSD in Sepsidae. We
suggest that the dynamic and labile evolution of directional reversals in SSD in this group of flies, is likely mediated
by sexual selection on male size in combination with mating system shifts, and proximately mediated more
strongly by sexual divergence in development time rather than growth rates. Therefore, directional variation in SSD
and associated changes in larval development might be much more rapid, common and less constrained than
currently assumed.
Dispersal is a major driver of the latitudinal diversity gradient of Carnivora
Jonathan Rolland, [email protected], University of Lausanne, Switzerland; Fabien Condamine,
[email protected], University of Alberta, Canada; Champak Beeravolu, [email protected],
University of Montpellier, France; Frederic Jiguet, [email protected], Museum d'histoire naturelle, Paris; Helene
Morlon, [email protected], Ecole normale supérieure, Paris
Aim: Understanding the relative contribution of diversification rates (speciation and extinction) and dispersal in the
formation of the latitudinal diversity gradient – the decrease in species richness with increasing latitude – is a main
goal of biogeography. The mammalian order Carnivora, which comprises 286 species, displays the traditional
latitudinal diversity gradient seen in almost all mammalian orders. Yet the processes driving high species richness in
the tropics may be funda- mentally different in this group from that in other mammalian groups. Indeed, a recent
study suggested that in Carnivora, unlike in all other major mammalian orders, net diversification rates are not
higher in the tropics than in temperate regions. Our goal was thus to understand the reasons why there are more
species of Carnivora in the tropics.
Location: World-wide.
Methods: We reconstructed the biogeographical history of Carnivora using a time-calibrated phylogeny of the clade
comprising all terrestrial species and dispersal–extinction–cladogenesis models. We also analysed a fossil dataset of
carnivoran genera to examine how the latitudinal distribution of Carnivora varied through time.
Results: Our biogeographical analyses suggest that Carnivora originated in the East Palaearctic (i.e. Central Asia,
China) in the early Palaeogene. Multiple inde- pendent lineages dispersed to low latitudes following three main
paths: toward Africa, toward India/Southeast Asia and toward South America via the Bering Strait. These dispersal
events were probably associated with local extinctions at high latitudes. Fossil data corroborate a high-latitude
origin of the group, followed by late dispersal events toward lower latitudes in the Neogene.
Main conclusions: Unlike most other mammalian orders, which originated and diversified at low latitudes and
dispersed ‘out of the tropics’, Carnivora originated at high latitudes, and subsequently dispersed southward. Our
study provides an example of combining phylogenetic and fossil data to understand the generation and
maintenance of global-scale geographical variations in species richness.
31
Teenage mutant hantavirus? Revised time-scales of RNA virus evolution based on spatial information
Moritz Saxenhofer, [email protected], University of Bern; Vanessa Weber de Melo,
[email protected], University of Zurich; Rainer G. Ulrich, [email protected], FriedrichLöffler-Institut; Gerald Heckel, [email protected], University of Bern
Time scales of molecular change in (rapidly evolving) pathogens are of major concern in the context of public health
and evolutionary biology. Typically, dating the emergence of a pathogen strongly relies on accurate estimates of
evolutionary divergence based on sequence data. For pathogens evolving at high evolutionary rates, multiple
substitutions at the same position make it challenging to reconstruct older evolutionary processes correctly with
statistical models. For many viruses, time estimates based on molecular clock analyses frequently result in
surprisingly recent origins of only several hundred years which raises some concern about the accuracy of such
methods for deeply diverged sequences. Here we demonstrate for two widely-distributed European hantavirus
species that pervasive but only partially compensated mutational saturation leads to strong systematic
underestimation of evolutionary age. We present a novel approach to quantify saturation loads and estimate
minimum divergence by incorporation of geographic information on virus origin. Our analyses reveal very strong
relationships between geographical distance and various estimates of genetic divergence for both Puumala and
Tula hantavirus. We estimate that these viruses have originated more than 2500 years ago which is ten (to
thousand) times older than estimates from tip-dated molecular clock analyses. This new minimum age is in much
better accordance with evidence of coevolution between these hantaviruses and their respective hosts over
thousands of years. This study provides new insights on the time-scales of RNA virus emergence and strongly
contributes to a deeper understanding of evolutionary processes in rapidly evolving pathogens.
How much environmental niche variation can be explained? Plant ecological indicator values may hold
the answer
Daniel Scherrer, [email protected], University of Lausanne; Antoine Guisan, [email protected],
University of Lausanne
Species distribution models (SDMs) are amongst the most used techniques in ecology and biogeography. SDMs
establish a statistical relationship between environmental variables (predictors) and observed species occurrences
to estimate the environmental niche of species. Therefore, it is essential that the chosen predictors reflect the most
relevant factors for plants (energy, water, light and nutrients). However, it is still unclear how well the commonly
used predictors reflect these factors and, in a more general context, how much of the observed distributions of
plant species can be explained by environmental factors. Here, we present an approach using ecological indicator
values (EIVs; Landolt) to provide a fist answer to this important question. We used EIVs as predictors in SDMs (1) to
see if they allow superior prediction, (2) to assess which important environmental factors we might be missing and
(3) to check if they provide a new kind of information still lacking in most SDMs. Our results showed, that SDMs
using ecological indicator values as predictors had a superior performance compared to models using commonly
used predictors such as precipitation, solar radiation and digital elevation models. It seems, that the commonly
used environmental predictors are very good at representing plant available energy (temperature) while we seems
to fail at representing plant available light (by global radiation), water (by precipitation) and nutrients (mostly
nothing at all). Our study highlights the importance to develop more plant relevant predictors that would allow a
considerable improvement of predictions. Nevertheless, even with an “optimal set of predictors”, here represented
by the EIV, there remains a large amount of unexplained variance in species distributions. Part of this variance
might be explained by non-climatic factors such as disturbance or anthropogenic factors but it seems a large part is
simply due to the stochastic nature of (meta-)population dynamics.
32
Microevolutionary differentiation in two hybridizing species of the Carex flava group
Lisanna Schmidt, [email protected], University of Bern; Markus Fischer, [email protected],
University of Bern
Geographic variation in combination with hybridisation and introgression between related species can lead to the
regional differentiation, in terms of karyological, genetic and phenotypic variation. We studied two closely related
aneuploid species of the Carex flava species group, C. flava, C. viridula and their hybrids. We studied 667 genets
from 55 populations situated in three climatically different regions (cold and relatively dry Estonia; warm and moist
lowland Switzerland; cold and moist highland Switzerland (for which we found no hybrids)). We investigated
morphological, karyological and genetic variation within and between the species for the three regions and we
transplanted replicates of all genets to three experimental gardens in the three regions to address phenotypic
plasticity in response to the local environment.
Based on morphology and microsatellite variation, C. flava genets of highland Switzerland differed from those of
the other two regions and genets of C. viridula differed in all three regions and also from C. flava. Hybrids were
intermediate between the parental species for some traits and transgressive for others. In lowland Switzerland
hybrids were closer to C. flava and in Estonia to C. viridula. Chromosome counts confirmed aneuploidy and differed
between the Carex species, for hybrids were not possible due to irregular chromosome pairings. Reciprocal
transplantation of all genets between the three regions showed strong morphological effects of the three gardens
and less pronounced effects of the region of origin. While this confirmed differentiation between species and
regions, and an intermediate position of hybrids, it also revealed a strong role of phenotypic plasticity.
We conclude that C. flava and C. viridula are indeed different species, despite clear affects of aneuploidy,
hybridisation, introgression and phenotypic plasticity, which may explain the observed position of the hybrids
relative to their parents. We suggest that systematical studies should combine morphological, genetic and
experimental approaches.
Does nature play the rock-paper-scissors game? Investigating the role of intransitive competition for
species coexistence
Santiago Soliveres, [email protected], University of Bern; Eric Allan, [email protected],
University of Bern
Most ecological theory assumes that there is a strong hierarchy in competition in natural communities, where the
best competitor displaces all others and so forth (A > B > C). Thus, the coexistence of many species depends on the
dominant species limiting itself more than others (niche segregation) or on third parties (such as herbivores)
reducing its competitive strength. A complementary mechanism that could explain why many species can coexist
when competing for very few different resources is, nevertheless, the lack of this strong competition hierarchy. This
is known as rock-paper-scissors dynamics (as analogy to the famous game) or intransitive competition. Under
intransitive competition, there is no clear competitor winner, as one species can displace some others, but it is at
the time limited by third species (A > B > C > A). Intransitive competition has attracted ecologists during 40 years,
yet its empirical support is scarce and limited mostly to mathematical models and three species experiments. We
first developed a method to measure competition intransitivity with field observations, then applied it to
observational datasets of plant and moss communities and lastly evaluated coexistence in experimental
communities of plants, mosses and saprophytic fungi differing in their degree of intransitivity. We found a high
level of intransitivity in both plant and moss communities, which largely matched the one found in experimental
communities. These intransitive competition networks are nested (i.e., dominant plants compete among each
other in a non-hierarchical system, and the same applies to rare species, but competition is hierarchical between
dominant and rare species). Higher levels of competition intransitivity were related to an increase (~10%) in species
richness and limited by more intensive land-uses. We will further discuss the role of intransitivity for biodiversity
and ecosystem functioning and also its potential applications to other areas of biology.
33
Vocal flexibility in forest guenon communication: the ontogeny of alarm call systems
Claudia Stephan, [email protected], University of Neuchatel; Klaus Zuberbühler,
[email protected], University of Neuchatel
Humans’ unique ability to use language for communication is today’s top candidate for what distinguishes us from
the rest of the animal kingdom. Humans are effortlessly able to express complex ideas and beliefs in varying
contexts, taking the level of knowledge of others into account. Until now, this high level of vocal flexibility is
unparalleled in all other communication systems and its evolutionary precursors remain nebulous. Systematic
comparisons of primates’ vocal systems between ecologically intact habitats and habitats that are impoverished in
their ecological complexity (e.g. due to habitat fragmentation or the extinction of predators) is expected to reveal
fascinating insight into the flexibility of signal production and interpretation among non-human primates.
We conducted playback experiments to address various aspects of cognitive abilities underlying call utterance and
signal interpretation in four monkey species (Cercopithecus campbelli, Cercopithecus diana, Cercopithecus
nictitans, Procolobus verus) in two West-African habitats, at Tiwai Island (Sierra Leone) and in Taï Forest (Ivory
Coast). While one of the monkeys’ predators, the leopard (Panthera pardus), is present in Taï, it went extinct at
Tiwai at least 30years ago. We especially focused on differences in communicative traits as a function of
ontogenetic experiences and compared communicative systems of the same species across habitats and of
different species within habitats.
We found consistent differences in vocal systems between populations of the same species, most likely due to
differences in predator presence. Although basic cognitive capacities, like e.g. categorisation of conspecifics on the
basis of social familiarity, are shared across habitats, their expression is more flexible than previously thought.
Forest guenons not only seem to interpret familiar or unfamiliar alarm calls on the basis of the environment they
are living in, (reflecting different levels of predatory threats or resource competition), but also use different
acoustic cues to vocally indicate their assessment.
Risk of transmission predicts avoidance of visual and chemical cues of infected conspecifics
Jessica Stephenson, [email protected], ETH Zürich; Sarah Perkins, [email protected], Cardiff University;
Joanne Cable, [email protected], Cardiff University
Associating with conspecifics infected with an infectious disease likely increases the risk of becoming infected, but
engaging in avoidance behavior incurs the cost of lost social benefits, such as antipredator defense. We
hypothesized that the outcome of this trade-off depends on the probability of an infected individual transmitting
its parasites: uninfected individuals may only avoid infected conspecifics that pose a high transmission risk. We
used the guppy Poecilia reticulata-Gyrodactylus turnbulli host-parasite system in two experiments testing this
prediction. In dichotomous choice tests, uninfected guppies avoided both the chemical and visual cues of
conspecifics in the late, but not early stages of infection. A transmission experiment indicated that avoidance
behavior coincided with when G. turnbulli is most likely to transmit between guppies. Our results therefore confirm
that infection avoidance behavior is based on multimodal, redundant cues, and is threat-sensitive, i.e. proportional
to the level of transmission risk posed by infected conspecifics.
34
Reciprocal allogrooming among Norway rats
Binia Stieger, [email protected], University of Bern; Manon K. Schweinfurth,
[email protected], University of Bern; Michael Taborsky, [email protected],
University of Bern
Reciprocity is one of several mechanisms establishing evolutionarily stable levels of cooperation among animals.
The logic of reciprocal cooperation implies that a costly act by an individual benefits a recipient that subsequently
returns the favour, hence involving an exchange of roles between donors and recipients. By alternating the roles,
benefits outweigh the costs. Norway rats (Rattus norvegicus) frequently show allogrooming behaviour.
Allogrooming represents a beneficial act for the recipient, but it is costly for the donor. In this study, we tested
experimentally whether rats reciprocally exchange grooming bouts. Further, we investigated the role of
hierarchical relationships for reciprocal exchanges. We manipulated the grooming rates experimentally, which
allowed us to establish randomly selected ‘cooperative’ and ‘defective’ social partners. We tested the response to
dominant and subordinate partners for each of these treatments. Our results show that rats reciprocate
allogrooming bouts according to a tit-for-tat-like decision rule, and that they groom up the hierarchy: Cooperative
individuals receive more grooming bouts in general than defective ones, whereas dominant partners get groomed
more frequently than subordinate partners. This shows that rats apply the decision rules of direct reciprocity, “help
someone who has helped you before”, not only in a food exchange task, but also in the context of mutual hygiene.
Predicted European range of potential ragweed biological control agents
Yan Sun, [email protected], University of Fribourg; Olivier Brönnimann, [email protected], University of
Lausanne ; George Roderick, [email protected], University of California, Berkely; Alexander Poltavsky,
[email protected], Sounthern Federal University; Suzanne Lommen, [email protected], University of
Fribourg; Heinz Müller-Schärer, [email protected], University of Fribourg
Our main objective is to provide a first analysis of distribution and habitat suitability of a major plant invader,
Ambrosia artemisiifolia, and of six promising potential biocontrol agents (Ophraella communa, O. slobodkini,
Zygogramma disrupta, Z. suturalis, Epiblema strenuana and Tarachidia candefacta) in the introduced European
range. More specifically, we asked: 1) what percentage of the suitable A. artemisiifolia range do the six biocontrol
agents cover, both under current and future bioclimatic conditions; 2) Can the cover of biocontrol agents on A.
artemisiifolia at home (North America) be transferred to their projected cover in the introduced range? Can we
choose the most suitable agent based on its distribution at home? 3) Which part of the suitable A. artemisiifolia
area in Europe will not be covered by these six agents?
Based on our species distribution models, we found that under both current and future bioclimatic scenarios, T.
candefacta is expected to cover the largest A. artemisiifolia area in Europe (20.2% and 18.4%, respectively). Total
cover of all six potential biocontrol agents combined in Europe is significantly less than in their native range in
North America (26.9% vs. 85.5%, P = 0.03 and 22.9% vs. 81.3%, P = 0.03; respectively). Interestingly, the cover of six
agents at home highly correlates with the cover in the introduced range (Spearman's rho. = 0.94, P = 0.02). Hence,
the coverage of biocontrol agents at home has considerable predictive ability to transfer to the introduced range.
We also predict that the a large part of the A. artemisiifolia area in Central and Northern Europe will not be covered
by the selected potential biocontrol agents, and thus efforts are needed to find additional agents.
35
The geography of parthenogenesis: what we really know
Anaïs Tilquin, [email protected], University of Zürich
When the geographic distribution of a parthenogenetic species differs from the one of its closet sexual relative,
authors talk about 'geographic parthenogenesis'. However, what really hides behind those two words is a
perplexing array of geographic patterns and reproduction modes, and this diversity is rarely wholly embraced in
theoretical reviews. Yet, to hope to derive insights into ecological conditions that could be favouring sex or asex,
and evaluate the relevance of the many explanatory hypotheses, it is crucial to critically and quantitatively answer
the simple questions: what kind of parthenogens are found where, how often, and how is that different from null
expectations of speciation models?
Royalty in danger! The influence of neonicotinoid pesticides on honey bee (Apis mellifera) queen
health
Aline Troxler, [email protected], Institute of Bee Health, Vetsuisse Faculty, University Bern; Geoff
Williams, [email protected], Institute of Bee Health, Vetsuisse Faculty, University Bern; Selina
Bruckner, [email protected], Institute of Bee Health, Vetsuisse Faculty, University Bern; Panuwan
Chantawannakul, [email protected], Faculty of Science, Chiang Mai University; Kitiphong Khongphinitbunjong,
[email protected], School of Science, Mae Fah Luang University; Gina Retschnig,
[email protected], Institute of Bee Health, Vetsuisse Faculty, University Bern; Kaspar Roth,
[email protected], Institute of Bee Health, Vetsuisse Faculty, University Bern; Dave Shutler,
[email protected], Department of Biology, Acadia University; Lars Straub, [email protected],
Institute of Bee Health, Vetsuisse Faculty, University Bern; Orlando Yanez, [email protected],
Institute of Bee Health, Vetsuisse Faculty, University Bern; Laurent Gauthier,
[email protected], Agroscope, Swiss Bee Research Centre; Peter Neumann,
[email protected], Institute of Bee Health, Vetsuisse Faculty, University Bern
Honey bees, Apis mellifera, have reproductive division of labor among females that enforces the importance of
queens (= primary reproductive individuals) in colony function. Lately, beekeepers in Europe and North America
have implicated poor queens as causes of colony mortality, and neonicotinoid pesticides represent one stressor
that might be involved. Effects of these pesticides on workers (mainly non-reproductive females) have been widely;
however, few studies have directly evaluated their effects on honey bee queens; we did this here.
Over two years, 18 queenright colonies were exposed to sub-lethal, field realistic doses of the neonicotinoids
thiamethoxam and its metabolite clothianidin via pollen supplements for ~5 weeks. Colonies were randomly
assigned to either control or pesticide treatments (both pesticides together). During the final week of exposure,
colonies were stimulated to rear queens. After emergence, queens were placed in mating nucleus colonies (N=28 &
30 for control and pesticide, respectively). Then, behavioral, physiological, and anatomical reproductive parameters
were recorded, including queen fighting (N=15 each consisting of a control vs. pesticide) as a proxy of physical and
cognitive abilities.
Pesticides significantly affected multiple aspects of queen reproduction, including overall success (queens lived and
laid diploid eggs), spermathecal sperm quantity, and ovary size; however, they did not affect queen survival on its
own, number and duration of mating flights, or spermathecal sperm vitality. The data also show that these
pesticides significantly reduced queens’ ability to fight. These results suggest that exposure to thiamethoxam and
clothianidin at environmental-relevant levels during development can have strong negative effects on honey bee
queens. These substances might therefore contribute to poor queen health recently observed in many regions of
the northern hemisphere.
36
Functional, not phylogenetic diversity determines the strength of species interactions among plants in
the Tibetan alpine meadows
Patrick Venail, [email protected], Université de Genève
The competition-relatedness hypothesis suggests that closely related species, being more ecologically similar,
should compete more intensely than less related species. While this hypothesis has important potential
applications for the understanding of community structure and ecosystem functioning, there is limited empirical
evidence to support it. At least two basic conditions need to be met in order to expect this hypothesis to be
supported by empirical evidence: phylogenetic signal of traits involved in species interactions and stronger
competition as species are more ecologically similar. We ran a field experiment in the Chinese Tibetan plateau to
assess how the nature and strength of interactions among twelve alpine meadow plant species were influenced by
their evolutionary relatedness and functional similarity based on five aboveground functional traits. For each plant
species we compared its biomass production when grown alone to its biomass in presence of another species as a
measure of species interactions. We found that competition between species was more frequent than facilitation,
with 60% of interactions resulting in plants producing less biomass when a second species was present. We found
no effect of phylogenetic relatedness on the nature or strength of species interactions, presumably as none of the
traits showed phylogenetic signal. Functional diversity based on maximum height only was the best predictor of
species interactions, followed by functional diversity using all five functional traits. Functional diversity based on
other three functional traits could not determine species interactions. In conclusion, the phylogenetic relatedness
of the alpine meadow plants from the Chinese Tibetan plateau did not predict the nature or strength of their interspecific interactions, rejecting the competition-relatedness hypothesis. On the contrary, depending on the traits
being used, functional similarity among species was a good predictor of species interactions, supporting recent
claims that traits are key for understanding community assembly.
Rapid spread of self-compatibility in different pollinator services
Marie Voillemot, [email protected], University of Lausanne; John R. Pannell, [email protected],
University of Lausanne
Evolution toward selfing is one of the most frequent transitions to have occurred in flowering plants, and its causes,
mechanisms and consequences continue to pose puzzles. Specifically, it is still not clear how self-incompatible (SI)
and self-compatible (SC) plants interact with each other when competing in similar environments and how one
strategy might spread into populations in which it is absent. I will report on a multi-generation experiment with the
plant Linaria cavanillesii, which shows among population variation in mating systems, to ask (1) whether one
mating strategy performs better than the other when competing in similar environment, (2) how much these
differences can influence a mating-system shift, and (3) how competition between two contrasting strategies
depends on pollinator availability. Six mixed arrays were composed of 12 SC and 12 SI plants, with different
treatments levels of of exposure to pollinators. Reproductive success was estimated using fruit set and paternity,
and selfing rates were measured for each plant’s progeny. We present here results for two successive generations,
in which a rapid shift from SI toward SC is observed under most conditions.
37
Natural Selection Drives Sperm Competition in the Species Complex Ophioderma longicauda
Alexandra A.-T. Weber, [email protected], University of Basel; Laurent Abi-Rached, [email protected], Aix-Marseille Université; Nicolas Galtier, [email protected], Université de Montpellier II;
Aurélien Bernard, [email protected], Université de Montpellier II; Olivier Bouchez,
[email protected], INRA; Juan I. Montoya-Burgos, [email protected], University of Geneva;
Anne Chenuil, [email protected], Aix-Marseille Université
Closely related species are interesting models to investigate mechanisms leading to reproductive isolation and
genome differentiation. The brittle star species complex Ophioderma longicauda encompasses several genetic
clusters, of which the cluster C3, a broadcast spawner, and the cluster C5, an internal brooder displaying derived
development and reproduction modes, represent distinct species living in sympatry. In this study, we performed de
novo transcriptome sequencing and assembly in the two closely related species to investigate the role of natural
selection in their reproductive isolation. In addition, we investigated the level of genetic diversity between this two
species. This analysis reconstructed 20,146 and 22,123 ORFs for C3 and C5, respectively, and characterized a set of
12,229 orthologs. Genetic diversity was 1.5 to 2 times higher in C3 compared to C5, confirming the tendency of
species with lower parental investment and large number of offspring to display higher genetic diversity. Forty-one
genes were the targets of positive diversifying selection during the evolution of the two species, eleven of which
could be successfully annotated. Notably, five of these eleven genes are involved in ion transport, and two of them
(NHE and TetraKCNG) are sperm-specific ionic channels involved in sperm motility, which is a major component of
sperm competition. This study thus shows that complete reproductive isolation between C3 and C5 is likely due to
increased sperm competition in C5, and not to fast evolution of gamete recognition proteins as previously shown in
other marine invertebrates.
The evolutionary ecology and genetic basis of thermal acclimation
Guillaume Wos, [email protected], University of Neuchâtel; Yvonne Willi, [email protected],
University of Basel
Frost and heat events are challenging for organisms that have climatic niches determined by temperature, and
especially for sessile organisms with limited capacity to escape. Nevertheless, adverse effects on fitness may be
lowered by pre-exposure to cold or heat, a process known as acclimation. To fully understand the ecological and
evolutionary implications of exposure to temperature extremes, we investigated (1) the magnitude of improved
thermal stress resistance due to acclimation, (2) the cost of acclimation, and (3) the genetic basis of acclimation.
We exposed young plants of North American Arabidopsis lyrata to short bouts of frost or heat and then used
electrolyte leakage to indicate their resistance to frost and heat stress. Acclimation increased thermal resistance
independent of acclimation temperature, but the response was higher when acclimation temperature
corresponded to the stress temperature (increase of frost resistance: + 3%; heat resistance: + 16%). We found that
both frost and heat acclimation were costly. RNA-transcriptome sequencing revealed that the pathways most
affected by frost acclimation were those involved in lipid processes, whereas pathways most affected by heat
acclimation were mainly involved in processes of the cell wall. Interestingly, defense pathways to biotic stress
(mainly fungi) were significantly down regulated, pointing to possible antagonistic responses to thermal stress and
disease.
38
Molecular evolution of Rubisco small subunits
Kana Yamada, [email protected], University of Lausanne; Romain Studer, [email protected], European
Bioinformatics Institute; Guillaume Besnard, [email protected], University of Toulouse 3; Nicolas
Salamin, [email protected], University of Lausanne
Rubisco is the most abundant protein on Earth. It is composed of eight small subunits (rbcS) and eight large
subunits (rbcL), which are located in the nuclear and plastid genomes of higher plants, respectively. Although rbcL
is a single copy gene, rbcS shows a large variationin gene copy numbers between species. The exact roles of each
copies of rbcS and their implication in the photosynthesis have not been clearly described. Further, little is known
about the evolutional history of rbcS, in contrast to the well studied rbcL. We studied the evolutionary history of
each gene copies of rbcS across flowering plants using phylogenetic analyses. The duplication history of rbcS was
very different in grasses than in other eudicots. Although in the latter we could detect duplication events at the
base of most plant families, rbcS copies in grass species clustered in a species-specific manner. This could be
explained by the presence of gene conversion events during its evolution. We further assessed the levels of
selective pressure occurring during the evolution of rbcS and estimated sites of rbcS that were coevolulving with
rbcL. We finally measured the structural stability of the different copies of rbcS when they bind to the rbcL subunit.
In most species, paralogous gene copies were more closely related to each other than orthologous gene copies.
This was again not the case in grasses where species-specific gene copies showed similar stability measures.
Forest biodiversity in Switzerland – new avenues provided by LiDAR remote sensing
Florian Zellweger, [email protected], ETHZ and WSL Birmensdorf; Kurt Bollmann, [email protected],
WSL Birmensdorf
Studies of biodiversity patterns and processes in forests can greatly profit from emerging remote sensing
technologies, such as Light Detection and Ranging (LiDAR), which provides contiguous and detailed information
about 3D vegetation structure. However, the integration of such data and methods into the fields of ecology,
biogeography and conservation is still far from mature. We used species occurrence data of vascular plants,
bryophytes, molluscs, butterflies, breeding birds and bats collected in Swiss forests to compare the importance of
LiDAR-derived forest structure relative to other environmental predictors of species richness and habitat use, such
as climate and edaphic features. We found that forest structure is a universal driver of species richness across taxa
and that climate-based predictions of butterfly and bird species richness were significantly improved by forest
structure. We showed that the strength and direction of the effects of different environmental predictors on
species richness were taxon-specific and that there is little spatial congruence between species richness patterns of
different taxa in Swiss forests. We further found that, according to their wing shape and echolocation traits, bats
responded to vertical forest structure and canopy surface characteristics, both of which not being readily available
from field measurements. LiDAR provides ecologically meaningful measurements of forest structure that informs
forest management about biodiversity patterns and potential in situ management options to improve the habitat
quality. LiDAR considerably increases the scope of inference for future studies that investigate the effect of forest
structure and associated habitat quality on species diversity and habitat use.
39
Negative Impacts of artificial lighting on nocturnal flower visitation and pollination success in Cirsium
oleraceum
Leana Zoller, [email protected], University of Bern; Eva Knop, [email protected], University of Bern
Artificial lighting is worldwide rapidly increasing with an estimated rate of 6% per year. Although we know that
organisms do respond to artificial lighting with changes in behaviour and physiology, there is very little known
about the impact on biological diversity and ecosystem functioning. In 2015, we thus investigated how artificial
lighting influences nocturnal pollinator visitations to a model plant species, Cirsium oleraceum, and we assessed its
impact on the fitness of the plant. To do so, we conducted an experimental field study on seven artificially
illuminated and seven dark control sites in the Bernese Mountains, and we assessed nocturnal visitors to
C.oleraceum and its seed set. We show that the number of nocturnal flower visitors and the number of seeds are
significantly reduced under the light treatment. To our knowledge, this is the first time that the impact of nighttime illumination on the ecosystem service pollination has been investigated. We conclude that the increasing
artificial lighting will worsen the worldwide pollinator crisis.
40
Flash talks (posters)
41
Reciprocal trading, a question of sex?
Jonathan Aeschbacher, [email protected], University of Bern; Manon K. Schweinfurth,
[email protected], University of Bern; Michael Taborsky, [email protected],
University of Bern
Cooperation is widespread in animals and reciprocity is one of the mechanisms maintaining cooperation.
Reciprocity refers to the mutual exchange of favours between one or more individuals. Three different forms of
reciprocal decision rules have been demonstrated in female Norway rats (Rattus norvegicus), corresponding to
generalized, direct and indirect reciprocity. As male rats are more aggressive among each other and establish a
dominance hierarchy between them, it is unclear whether they also apply these decision rules. In the generalized
reciprocity paradigm, the propensity to help an unknown partner is based on previous interactions with another
partner. Here we test whether male rats reciprocate received help according to the rule “help anyone if helped by
someone”, i.e., generalized reciprocity. We used a two-player food exchange task. A focal rat received food
provided by several rats, one at a time on subsequent days. On another day, focal rats had the opportunity to pay
back the experienced favours to an unfamiliar and unrelated conspecific. As a control, males could pull for an
empty cage in order to check if they understand the social dimension of the test. In contrast to female rats, males
did not provide more food to unknown conspecifics after experiencing cooperation from someone else. However,
the focal rats provided more food to a partner than to an empty cage, suggesting that they had understood the
social context of the experiment. We conclude that the propensity to give provisions to conspecifics is influenced
by social partners also in male rats, but that they do not reciprocate favours to anonymous partners if they
received help from others. This sex difference is probably due to different social relations among male and female
rats.
How to observe the invisible: A novel tag-and-trace system to investigate the chemical biology of rootherbivore interactions
Zoe Bont, [email protected], University of Bern; Matthias Erb, [email protected], University of Bern
Despite the important role of root-feeding arthropods for natural and agricultural ecosystems and the increasing
knowledge about root defense metabolites, few attempts have been made to understand the influence of plant
secondary compounds on spatial and temporal foraging of root feeders in their native environment. One reason for
this gap of knowledge is the lack of suitable underground behavior monitoring tools. We therefore developed a
novel tag-and-trace system by fitting copper rings around the neck of third instar larvae of the common cockchafer
(Melolontha melolontha). A commercial handhold metal detector was adapted to trace the movements of the
larvae under realistic soil conditions. To validate the system, we profiled the movement and feeding patterns of
tagged and non-tagged M. melolontha in the rhizosphere of their preferred host plant, the common dandelion
(Taraxacum officinale agg.), using X-ray microCT scanning. We found no differences in amount and type of
consumed root material for tagged and non-tagged M. melolontha. However, tagged grubs moved more slowly
that non-tagged grubs. From this experiment, we conclude that the system is useful for small-scale experiments,
but may underestimate larval movement in large soil volumes. As a first application, we used the system to
understand the role of taraxinic acid glucoside, a sesquiterpene lactone that is involved in T. officinale defense [1],
as a determinant of M. melolontha behavior. Using transgenic TA-G deficient T. officinale plants, we show that M.
melolontha prefers TA-G deficient over wildtype plants when the genotypes are growing close together, but shows
no clear preference when the plants are grown at a distance of more than 15 cm. Further behavior experiments
indicate that the feeding preference of M. melolontha depends on the grub’s ability to taste the roots directly.
[1] Huber et al., PLoS Biology, in press.
42
Effect of non-random pairing and post-copulatory selection on the proportion of colour-related MC1R
genotypes
Valérie Ducret, [email protected], University of Lausanne; Alexandre Roulin, [email protected],
Unversity of Lausanne; Jérôme Goudet, [email protected], University of Lausanne; Arnaud Gaigher,
[email protected], University of Lausanne; Céline Simon, [email protected], University of Lausanne
Numerous mechanisms are responsible for the evolution of colouration in natural populations but still little is
known about their interactions and consequences on genetic diversity. In the present study, we investigated
whether variation in the frequency of a gene with strong effect on plumage colouration is sensitive to both sexual
and natural selection. We examined whether genotypes at the melanocortin-1-receptor (MC1R), a gene that
regulates melanogenesis, pain perception and inflammatory processes, fit with the Hardy-Weinberg principle in
male and female nestling barn owls (Tyto alba). In Europe, the ancestral MC1RWHITE allele is associated with
whitish plumage while the derived MC1R-rufous allele comes with a dark rufous plumage. During a period of 15
years, we monitored the frequency of MC1R-white (85%) and MC1R-rufous (15%) in 2,947 fledglings. There was an
overall deficit in the proportion of heterozygotes in both males (7.5%) and females (12.9%). Pairing with respect to
MC1R was slightly assortative and accounts for 5% of the overall heterozygote deficiency. In addition, we detect
post-copulatory selection with possible egg-sperm recognition (rather than MC1R-specific nestling mortality),
which may have evolved in order to differentially manipulate the frequency of each MC1R genotype in sons and
daughter, hence influencing MC1R genotype proportions. Our study highlights the importance of monitoring
variation in gene frequencies at different life history stages to understand how selection is exerted even before the
phenotype of interest (here colour) is actually expressed.
MHC diversity linked to fitness-related traits
Arnaud Gaigher, [email protected], University of Lausanne; Reto Burri, [email protected], Uppsala
University; Walid Gharib, [email protected], University of Bern; Pierre Taberlet,
[email protected], Université Joseph Fourier; Alexandre Roulin, [email protected], University
of Lausanne; Luca Fumagalli, [email protected], University of Lausanne
Major histocompatibility complex (MHC) genes play an essential role in the adaptive immune response and thus
constitute a good model to study adaptive genetic variability. Despite a growing body of empirical data, the role of
pathogens in maintaining a high level of MHC diversity in natural populations needs further investigation. It
remains unclear, whether the MHC evolves under heterozygote or rather rare-allele advantage. The barn owl (Tyto
alba) exhibits a number of characteristics that make it an ideal model to study MHC diversity. Indeed it is one of the
most widespread birds worldwide and it has been shown that this species exhibits mate choice related to an
ornamental trait that is associated to parasite resistance. Here, our goal is to study the association between the
MHC diversity and fitness-related traits. To do this, we used high-throughput sequencing to sequence both MHC
class IIB and MHC class I loci in a large number of individuals sampled in Switzerland, for which information related
to individual fitness is available (e.g. immunocompetence, parasite fecundity). We examined the effects of
particular alleles and MHC diversity on these fitness parameters. Our results indicate a positive effect of
heterozygosity on parasite resistance, in agreement with expectations of the heterozygote advantage hypothesis.
Therefore, this study provides relevant perspectives for the understanding of MHC evolutionary ecology.
43
Temporal and spatial scales matter: circannual habitat selection of bird communities in vineyards
Claire Guyot, [email protected], University of Bern; Raphaël Arlettaz, [email protected],
University of Bern & Vogelwarte; Alain Jacot, [email protected], University of Bern & Vogelwarte
Intensively cultivated vineyards are mostly surrounded by few natural structures and show little ground vegetation
on the cultivated area. However, the quantitative and qualitative aspects of the ground vegetation may vary
throughout the annual cycle with its concomitant effects on habitat selection of birds. Consequently, the
importance of vineyards for birds may change throughout the year with different bird communities occurring
throughout the seasons. Here, we aimed to get season-specific habitat preference curves to highlight the
importance of semi-natural habitat features as well as the ground vegetation on avian communities living within
vineyards. Habitat preferences were measured at two different spatial scales. Firstly, at the landscape scale we
monitored birds along 1-km transects over one whole year (February 2014 – January 2015). Second at the field
scale we compared vineyard characteristics of visited to unvisited parcels. Our results demonstrate that vineyards
with an increased amount of hedges and small wooded areas harboured significantly higher bird abundance,
species richness & species diversity independent of time of the year. At the field scale, birds showed a seasonspecific habitat selection pattern with a linear preference for more vegetated vine surfaces in winter. In spring and
summer, an optimum at intermediate ground cover was detected. These season-specific habitat preferences might
be related to species’ life-history where more insectivorous, ground-foraging species occur during the breeding
season compared to granivorous birds in winter. Most importantly, these results highlight the importance
investigating habitat preferences along the annual cycle that should allow designing precise season-specific
management recommendations to promote avian biodiversity in vineyards.
Transcriptional differences associated with maternal investment in the Japanese quail
Kate Ihle, [email protected], University of Zurich
The cost of reproduction is thought to be a major regulator of life-history evolution. While selection favors
increased investment in reproduction, increased parental investment in offspring may come at the cost of selfmaintenance in the parents, and thus limit future reproduction. The regulation of the balance between
reproduction and self-maintenance is still poorly understood, but increased investment in reproduction is predicted
to come at the cost of immune function. In birds, maternal investment in egg components is extremely
energetically expensive, and large variations in the level of these maternally provided resources have been
documented in natural populations. In such populations, the limited availability of food and other resources is
often suggested to mediate life-history trade-offs. Here we examine the evidence for a reproduction-immunity
trade-offs at the transcriptional level in the absence of resource limitation in a captive population of Japanese quail
(Coturnix japonica) divergently selected for high versus low maternal investment in egg size. All females in this
population received ad libitum access to highly nutritious food. As such, any trade-offs between reproductive and
immune investment are more likely to be related to intrinsic factors than to external resource availability. Using
whole-transcriptome RNAseq, we identified 30 consistently differentially expressed genes in the ovarian follicle
cells of the high and low maternal investment lines. Genes associated with reproductive investment including
vitellogenin 2 and zona pellucida protein D are upregulated in the high maternal investment line, while genes
associated with immune function including toll-like receptor 3 and myxovirus resistance 1 are more highly
expressed in the low investment line. Our data provide evidence for a reproduction-immunity trade-off in the
absence of resource limitations in a precocial bird.
44
Diversification in the Amazon: testing the contribution of environmental heterogeneity, topographical
barriers and geographical distance a in the widespread characid Triportheus albus
Luiz Jardim de Queiroz, [email protected], University of Geneva; Juan Montoya Burgos,
[email protected], University of Geneva
Understanding the processes that drive fish population diversification in the Amazon is challenging due to its
immense extension, the many environments and the great biodiversity. We addressed this issue by determining the
population genetic structure of the characid Triportheus albus across the Amazon Basin and examining the
contribution of many potential explanatory factors. We tested for patterns of isolation-by-distance, isolation-bybarrier with the Teotônio Falls as a physical barrier, and isolation-by-environment using three environmental
variables: water color, floodplain size, and riparian forest composition. Phylogenies and populations genetic
analyses based on mitochondrial and nuclear genes revealed a strong structuration with three groups: Negro and
Tapajós rivers (black- and clearwaters); Lower Madeira and Central Amazon (whitewaters); and Upper Madeira
(whitewaters), upstream of the Teotônio Falls. Using distance-based RDA, we show for the first time that all factors
are significantly correlated to the genetic structure. Thus, our results confirm that water color triggers an adaptive
response in this species, responsible for the marked structure observed between white and black- or clearwater
populations. The other environmental variables, floodplain size, vegetation composition, Teotônio Falls, and
geographical distance also explain part of the strong population structure. In conclusion, we show that multiple
diversification factors, individually proposed as drivers of population divergence, have been acting in conjunction
on T. albus, resulting in an unusually strong genetic structuration. We suggest that the accumulative action of
several population diversification processes may partly account for the high speciation rate characterizing the
Amazon region.
Ecological island syndrome in lycaenid butterflies
Darina Koubínová, [email protected], University of Lausanne; Tomasz Suchan,
[email protected], University of Lausanne; Roger Vila, [email protected], Institut de Biologia Evolutiva (CSICUPF), Barcelona, Spain; Nadir Alvarez, [email protected], University of Lausanne
Lycaenidae is the second largest butterfly family with a worldwide distribution. In approximately 75% of the about
6,000 currently recognized species, caterpillars have developed specific associations with ants, ranging from
mutualistic (the ants protect and tend the caterpillars, which in turn, produce nutritive secretions to feed the ants)
to antagonistic behavior such as parasitism and predation (caterpillars do not feed the ants and are, instead, fed by
them, through trophallaxis, or even predate on ant larvae). These relationships vary from facultative to obligatory
across the family, and this wide range of ecological interactions may have a contrasting effect on the rate of
genome evolution in lycaenids based on their level of ant-dependency. Additionaly, lycaenid butterflies show
different levels of dependency on host plants in the stages before being adopted by ants.
Here, we hypothesize that species with higher dependency on specific ant species should be characterized by
smaller populations and lower among-demes dispersal rate. This may result in a higher accumulation of withinspecies genetic variation due to stronger drift and lesser gene flow. In order to test this hypothesis, we apply
Restriction-site-associated-DNA sequencing (RAD-seq) in almost 1000 specimens from eight lycaenid species with
contrasted levels of ant and host plant dependency. We compare their amount of Single Nucleotide Polymorphisms
(SNPs) by analyzing genetic variation in several populations covering most of their distribution ranges and correlate
it with their level of ant and plant dependency.
45
Sex-chromosome differentiation covaries with polymorphism at the candidate sex-determination gene
Dmrt1 in common frogs
Wen-Juan Ma, [email protected], University of Lausanne; Nicolas Rodrigues, [email protected],
University of Lausanne; Roberto Sermier, [email protected], University of Lausanne; Alan Brelsford,
[email protected], University of California Riverside; Nicolas Perrin, [email protected], University of
Lausanne
Although sex chromosomes are generally homomorphic in amphibians (in sharp contrast with the highly
heteromorphic systems found across mammals, birds or Drosophila), X and Y haplotypes might present some
genetic differentiation. In common frogs (Rana temporaria), sex-chromosome differentiation has been shown to
vary with latitude across Sweden, in parallel with patterns of gonadal development. Frogs from the northern-boreal
population of Ammarnäs display well-differentiated X and Y haplotypes with no XY recombination, early sex
differentiation, and a perfect match between phenotypic and genotypic sex. Those from the southern population of
Tvedöra show no differentiated Y haplotypes and late sexual differentiation: most juveniles present ovaries at
metamorphosis, which in some individuals are replaced by testes at later developmental stages. Here we show that
these patterns covary with a polymorphism at the candidate sex-determining gene Dmrt1. In the northern
population, juveniles with the local Y allele always develop as males, and those without it as females. In the
southern population, juveniles with the local Y allele tend to ultimately develop as males; those without it may
nevertheless become functional males, but with strongly female-biased progeny. Large-scale sampling across Swiss
populations from different altitudes further supports an association between Dmrt1 polymorphism and sex
chromosome differentiation. Our results suggest that Dmrt1 contributes to sex determination range wide, but that
different alleles differ in sexualisation strength (feminization versus masculinization), and thus in the scope for nongenetic contributions to sex determination.
Impact of estrogen pollution on embryo viability and sex differentiation in grayling (Thymallus
thymallus)
Diane Maitre, [email protected], University of Lausanne; Lucas Marques Da Cunha,
[email protected], University of Lausanne; Claus Wedekind, [email protected], University of
Lausanne
The grayling population of Lake Thun suffers from a distorted operational sex ratio. One hypothesis is that this may
be due to poor water quality and infectious diseases. Among the most common endocrine disrupting chemicals is
17?-ethinyl estradiol (EE2), a component of contraceptive pills. EE2 affects embryo viability and sex differentiation
in some species (it can even induce sex reversal). Here we tested whether and how EE2 affects development of
grayling from the Lake Thun population. We bred F1s of wild caught spawners in vitro in a full-factorial breeding
design and exposed 12,935 grayling embryos to one of four different treatments: (i) an ecologically relevant
concentration of EE2 (1ng/L), (ii) the opportunistic pathogen Pseudomonas fluorescens (PF), (iii) a combination of
EE2 and PF, or (iv) a sham treatment (controls). We looked at treatment effects on early embryo viability traits such
as survival, hatching size, yolk sac volume at hatching, growth, and yolk sac consumption. After yolk sac
consumption, 300 fish from each treatment were transferred to 8 tanks (two replicates per treatment) and raised
for 4 months to study sex differentiation. The corresponding analyses are currently being performed and will be
presented at the meeting.
46
Urban biodiversity: Different responses of vascular plants, Orthopterans and Lepidoptera to habitat
size and landscape composition
Ramona Melliger, [email protected], University of Basel, Section of Conservation Biology; Hans-Peter
Rusterholz, [email protected], University of Basel, Section of Conservation Biology; Bruno Baur,
[email protected], University of Basel, Section of Conservation Biology
A basic challenge in conservation biology is to understand the impact of urbanization on biodiversity. However, the
response to human-induced disturbances may vary among and within different taxonomic groups. In this study, we
examined the effect of habitat size and landscape composition on species richness and traits of three taxonomic
groups (vascular plants, Orthopterans and Lepidoptera) in two different habitat types (meadows and ruderal sites)
in the city of Basel. We used species inventories from the natural heritage inventory of Basel-Stadt and GIS-based
landscape elements to examine species richness and species traits in relation to area and the contribution of
different landscape elements in the closer surrounding to the species richness of the three taxonomic groups.
The total species richness of Orthopterans and Lepidoptera was positively related to the area of meadows, but not
to the area of ruderal sites. The reverse species-area relationship was found for plants. Furthermore, the size of
meadows and ruderal sites differently affected single species traits of plants, Orthopterans and Lepidoptera.
Regarding landscape composition, the total species richness of the three taxonomic groups varied in the response
to the percentage cover of sealed areas and ruderal areas in the closer surrounding of the two habitat types
investigated. For example in ruderal sites, the species richness of both groups of invertebrates but not the species
richness of plants were positively affected by the percentage cover of ruderal areas.
Our results revealed different responses to urbanization depending on the habitat type, taxonomic group and
species trait investigated. Therefore, urban planners should consider different conservational strategies for natural
habitats potentially harbouring the target species but also focus on increasing the habitat quality of the closer
surrounding to sustain urban biodiversity.
Host-parasite specificity in the Apis-Varroa complex in Asia
Paul Page, [email protected], Agroscope - Swiss Bee Research Center; Ninat Buawangpong,
[email protected], Bee Protection Center, Department of Biology, University of Chiang Mai; Zheguang Lin,
[email protected], College of Animal Science, Zhejiang University; Huo-Qing Zheng, [email protected],
College of Animal Science, Zhejiang University; Fu-Liang Hu, [email protected], College of Animal Science, Zhejiang
University; Panuwan Chantawannakul, [email protected], Bee Protection Center, Department of Biology,
University of Chiang Mai; Peter Neumann, [email protected], Institute of Bee Health, University
of Bern; Vincent Dietemann, [email protected], Agroscope - Swiss Bee Research Center
The ectoparasitic mite Varroa destructor shifted from its original host, the Eastern honey bee (Apis cerana Fabr.), to
the Western honey bee (A. mellifera L.) and is now one of the major biotic threats to beekeeping globally. Previous
studies suggest that host specificity may exist between A. cerana host populations and their Varroa haplogroups,
which is relevant for our understanding of host-parasite adaptations. However, strong behavioral (reproductive)
and genetic data are often lacking to ascertain the basis of this specificity. Moreover, the biogeography of these
host-parasite associations has been elucidated based on mites of unidentified reproductive status. We readdressed
host specificity in this Apis-Varroa complex at a higher resolution by genetically identifying Varroa mites that are
able to effectively reproduce on local A. cerana lineages and on the long-time introduced A. mellifera in three
distant locations in Thailand. We also investigated the potential of multiple colony infestations, i.e. with more than
one mite haplogroup, relying on a large sample size within colony and within location. This approach will allow us
to define local adaptation and host specificity at a finer scale, providing us with a solid basis to unravel the
biological mechanisms underlying the apparent capacity of some V. destructor haplotypes to successfully infest A.
mellifera colonies worldwide.
47
DNA barcoding and soil biodiversity conservation
Eric Pinto-Figueroa, [email protected], University of Lausanne; Jan Roelof van der Meer,
[email protected], University of Lausanne; Antoine Guisan, [email protected], University of
Lausanne
Biodiversity loss by global change is a phenomenon demanding conservationists for strategies to overcome the
limited data, cornerstone for planning efficient conservation strategies. Despite of promising tools for biodiversity
conservation as remote sensing and high-resolution satellites, no explicit and functional strategies for conservation
of soil biodiversity have been proposed so far. In this study, using a DNA barcoding dataset of soil fungi obtained
from Swiss western Alps as case study, we evaluated a framework of using DNA barcoding for conservation of soil
biodiversity. Here, revealed three endangered fungal species according to the International Union for Conservation
of nature (IUCN) distributed in four geographic areas of potential conservation interest. We described a
comprehensible use of DNA barcoding for soil biodiversity conservation by focusing on richness and relative
abundance of soil fungal OTUs. As well, we describe the potential evaluation of climate change impact on soil
biodiversity by ecological niche modelling.
Museum genomics and past genetic diversity in an endangered grasshopper (Oedaleus decorus)
Sarah Schmid, [email protected], University of Lausanne; Nadir Alvarez, [email protected], University of
Lausanne; Raphaël Arlettaz, [email protected], University of Bern; Gerald Heckel,
[email protected], University of Bern; Camille Pitteloud, [email protected], ETH Zürich; Mila
Pajkovic, [email protected], University of Lausanne
Genetic variation in small populations is of concern because it is required for future adaptation. The extent of
genetic diversity loss in endangered species is often unknown because examination of past genetic diversity is
difficult to achieve. Museum specimens provide an under-exploited resource for population studies by increasing
the availability of genetic data. They potentially add an important temporal dimension to genetic studies because
they contain information about past genetic diversity, but also provide an access to specimens originating from
areas that could not easily be sampled. In this study, we focused on the genetic structure and diversity of Oedaleus
decorus, a grasshopper with a Palearctic distribution. Over the past century, populations from Central Europe
declined, but the extent of genetic diversity loss remains unknown. We applied an hybridization capture (HyRad)
approach to identify single nuclear polymorphisms in 121 historical museum samples and 63 modern samples. This
recent technique allows retrieving orthologous sequences even from highly degraded DNA samples. Investigation
of the genetic structure across the species geographical range showed four different genetic lineages across the
Palearctic. In Switzerland, where the species is currently considered as endangered, calculation of genetic diversity
over time was performed on 31 historical and 34 modern samples. Surprisingly, allelic richness and observed
heterozygosity were significantly lower in the past compared to modern populations. Fixation indexes (Fst) were
also calculated and compared between contemporary populations and populations from the 1940s. Population
differentiation was significantly higher in the past, providing a potential explanation of the higher level of genetic
diversity in current populations. Our results illustrate that museum genomics is a valuable source of information to
study centurial population processes.
48
A genome-wide analysis of experimental lineages of fruit flies exposed to chronic larval malnutrition
for over 150 generations
Roger Stillwell, [email protected], University of Lausanne; Martin Kapun, [email protected], University
of Lausanne; Tadeusz Kawecki, [email protected], University of Lausanne
Experimental evolution studies that are combined with whole genome sequencing offer great promise into
providing insights about the mechanisms that drive evolution. Here we present a genome-wide analysis of six
replicate lineages of Drosophila melanogaster that have been exposed to chronic larval malnutrition for >150
generations of selection. Compared to six replicate control populations, these populations now survive much better
and develop/grow markedly faster on the poor food. The selected populations also have considerably longer
development times and are smaller when raised on standard food. We pool sequenced 400 flies of each of the
selected and control lineages after selection was relaxed and the lines were raised on standard food for two
generations. We detected substantial differentiation at most places in the genome for the selected vs. control
lineages. We are currently identifying the top candidate genes and physiological pathways that are responsible for
this differentiation. We hope this will generate new hypotheses about the molecular and physiological basis of
improved malnutrition tolerance.
Trait–demography relationships underlying small mammal population fluctuations: the Chitty
hypothesis re-visited
Koen van Benthem, [email protected], University of Zurich; Hannah Froy, [email protected],
University of Edinburgh; Lowell Getz, [email protected], University of Illinois; Madan Oli, [email protected],
University of Florida; Arpat Ozgul, [email protected], University of Zurich
Large-scale fluctuations in abundance are a common feature of small mammal populations and have been the
subject of extensive research. These demographic fluctuations are often associated with concurrent changes in the
average body size of individuals, a phenomenon consistent with the idea that population regulation can occur
internally through changes in the quality of individuals, sometimes referred to as the Chitty effect. Despite its
plausibility, an empirical investigation of the mechanisms underlying the coupled dynamics of body size and
population growth has been lacking.
Using a trait-based demographic approach and life-history data from a 25-year study of the monogamous prairie
vole, Microtus ochrogaster, in Illinois, USA, we examined the relationship between body mass and demography in a
small mammal population that exhibits large-scale fluctuations in abundance. Specifically, we investigated how
trait–demography relationships and trait distributions changed between different phases of population fluctuations
and the consequences of these changes for both trait and population dynamics.
We observed phase-specific changes in body mass distribution in this population of prairie voles. Our analyses
revealed that these changes were driven by variation in ontogenetic growth, rather than selection acting on the
trait. The resulting changes in body mass influenced most life-history processes, and these effects varied among
the different phases of the population fluctuations. However, these changes did not propagate to affect the
population growth rate. The increase phase of the fluctuations was initiated by enhanced survival rates,
particularly of juveniles, whereas the decline phase was driven by an overall collapse in fecundity, survival and
maturation. The demographic causes of the observed population fluctuations were direct, environmental effects,
largely independent of body mass.
Our study provides empirical support for the absence of one aspect of the Chitty effect, in which changing traitdemography relationships drive population fluctuations, as well as a mechanism underlying the observed trait
changes accompanying population fluctuations.
49
Human dispersal and its individual- and population-level consequences
Nina Vasiljevic, [email protected], University of Zurich; Erik Postma, [email protected], University of
Zurich
Dispersal is ubiquitous, and individuals of most species disperse during some part of their life. This makes dispersal
the main mechanism driving gene flow, shaping patterns of genetic variation within and among populations. Here
we characterize dispersal behavior in humans, as well as its individual- and population-level consequences. First,
we use modern-day surname distributions to describe contemporary levels of population structure among villages,
and relate this to geography and religion. Second, we use a unique Swiss genealogical dataset covering over three
centuries to quantify historic dispersal rates and distances, and test how these relate to modern-day population
structure. Finally, we quantify the fitness consequences of dispersal by comparing the reproductive success of both
philopatric (i.e. non-dispersing) and dispersing individuals using generalized additive models (GAM). We provide
evidence for significant small-scale population structure, and a significant correlation between genetic distance and
both geographic distance and religious similarity. This is in accordance with low, female-biased historical dispersal
rates. In addition, we find lifetime reproductive success of dispersing women to be lower than that of philopatric
women, and show that these fitness costs of dispersal are mediated by differences in timing of reproduction. On
the whole, we provide evidence for relatively low levels of historical gene flow, contributing to remarkably strong
small-scale contemporary population structure. Thereby our results provide new insights into how human dispersal
behavior and its individual- and population-level consequences have shaped modern-day society.
Sex-chromosome differentiation and mating success in common frogs
Paris Veltsos, [email protected], University of Lausanne; Nicolas Rodrigues, [email protected],
University of Lausanne; Tania Studer, [email protected], University of Lausanne; Wen-Juan Ma,
[email protected], University of Lausanne; Roberto Sermier, [email protected], University of Lausanne;
Julien Leuenberger, [email protected], University of Lausanne; Nicolas Perrin, [email protected],
University of Lausanne
Sex-chromosome differentiation in common frogs show striking variation both within - and among populations.
This variation was recently shown to correlate with a polymorphism at the candidate sex-determining gene Dmrt1
(Ma et al. submitted): some Dmrt1 alleles associate with clearly differentiated Y haplotypes, while others associate
with undifferentiated (X-like) haplotypes. We sampled over 500 males from a high altitude Alpine population,
which were genotyped and measured for phenotypic traits and mating success. While we did not find any effect of
Dmrt1 alleles or Y-haplotype differentiation on phenotypic traits, males with a male-specific Dmrt1 allele in a
differentiated Y-haplotype background had a higher mating success than those with a male-specific Dmrt1 allele
but an otherwise undifferentiated (X-like) haplotype, suggesting epistatic interactions between Dmrt1 and other
genes on the sex-chromosome haplotype.
50
Do ants with alternative forms of social organization carry different bacterial endosymbionts?
Sze Huei Yek, [email protected], University of Lausanne; Ludovic Andreotti, [email protected],
University of Lausanne; Amaury Avril, [email protected], University of Lausanne; Michel Chapuisat,
[email protected], University of Lausanne
Insects often harbor bacterial endosymbionts that can profoundly affect the ecology, behaviour and evolution of
their hosts. For example, maternally-inherited Wolbachia are known for enhancing their own transmission by
manipulating host reproduction. Some populations of ants harbour multiple endosymbionts, but the relationship
with social organization remains unclear. We study a socially polymorphic ant species in which the social
organization is controlled by a supergene. The genotypic distribution at the supergene across colonies indicates
that female gene flow is restricted between monogynous (= single-queen) and polygynous (= multiple-queen)
colonies. Such matrilineal isolation between social forms raises the possibility that monogynous and polygynous
colonies harbour different bacterial endosymbionts. We use a combination of field work, MiSeq 16S rDNA
metabarcoding and phylogenetic analyses to get an overview of the diversity of microbial endosymbionts across
host social forms and populations. This study provides insights into the bacterial endosymbionts of ants and reveals
novel links between social organization, genetic structures and endosymbionts.
Simulating bryophytes' dynamic response to climate changes in Europe using mixed model approach
Florian Zanatta, [email protected], Université de Liège; Robin Engler, [email protected], Université
de Lausanne; Olivier Broenimann, [email protected], Université de Lausanne; Antoine Guisan,
[email protected], Université de Lausanne; Jairo Patiño, [email protected], Instituto de Productos
Naturales y Agrobiología; Alain Vanderpoorten, [email protected], Université de Liège
Dispersal capacity is a key parameter driving species dynamic responses to their environment. In the context of
climate changes, these dynamics take on even greater importance as the long-term survivability of species depends
on their ability to effectively shift (or augment) their distributions according to changes in local climatic conditions.
In this study we focused on a set of spore-producing plant species (bryophytes) in an approach combining
environmental niche models and dispersal simulations, in order to predict the potential effect of climate changes
on these populations in a dynamic way, across Europe. For this purpose, we computed species-specific dispersal
kernels integrating both experimentally derived settling velocity parameters and global wind and elevation
databases to infer potential spores dispersal capacity. These simulations were then conducted over environmental
suitability map obtained with ecological niche models to account for potentially colonizable suitable habitat.
51
Posters
52
Selection coefficients when adaptation is polygenic - what do they express?
Matthias Ammann, [email protected], Zoological Institute of the University of Basel; Lea Waldner,
[email protected], Zoological Institute of the University of Basel; Daniel Berner,
[email protected], Zoological Institute of the University of Basel
Understanding how strongly selection has acted on a favourable allele is an important issue in population
genomics. One way to estimate selection coefficients on focal loci is to combine information on the duration of
selection with an observed allele frequency shift over time. This approach generally ignores that adaptation to
novel environments will usually occur from standing genetic variation with selection acting on multiple loci. Using
individual-based simulations, we here explore how the fixation trajectory of an initially rare beneficial allele is
modified by joint selection on other loci in the genomic background. Our main findings include that the fixation
speed (but not the fixation probability) of a given allele is positively related to the number of other loci under
selection across the genome. This holds irrespective of whether loci segregate freely or are physically linked, unless
the recombination rate is very low. Our study thus indicates that in empirical systems under polygenic adaptation,
selection coefficients will tend to be biased by the number of selected sites and thus are incomparable across
different study systems. Within a focal population and genomic background, however, relative differences among
loci in the strength of selection can be interpreted meaningfully.
Functions of Floral Signals in Biscutella laevigata
Mojtaba Bakhtiari, [email protected], University of Neuchatel
Floral signals such as color and scents help plants attract pollinators by advertising rewards. They may also function
as defence signals, in the form of herbivore-induced plant volatiles (HIPVs) signal, to defend plants against
antagonist visitors. Therefore, different signals can have different direct and indirect functions on pollination
biology with different flower visitors having different signal preferences. Based on these different preferences,
floral signals are expected to function differently to mediate generalist plants’ interaction with various flowervisiting insects across different geographical gradients. However, there has been a little consideration given to the
role of olfactory signals and testing the combination of signals in mediating such interactions. In this study, we
characterized the pollinator guilds visiting the flowers of Biscutella laevigata in two different populations in
Switzerland (lowland and mountain), identified the most abundant pollinators and measured their pollination
efficiency using bagged-plant experiments. We used behavioral assays and gas chromatography (GC-MS) to
identify floral signals attracting sawfly sp. Tenthredo; fly sp. Scatophagidae; Platypezidae, and predatory crab spider
Thomisus onustus. We performed a florivory experiment with Plutella xylostella moths to test for the production
of HIPVs in B. laevigata flowers. Our results showed Biscutella plants were most frequently visited by bees
(Halictus) and flies (Syrphus) in lowland, whereas sawflies (Tenthredo) and flies (Scatophagidae & Platypezidae)
comprised the most frequent visitors in the mountain with sawflies being the most efficient pollinators. Crab
spiders were attracted to both volatiles and color, but primarily by the volatile compound ?-ocimene when tested
over color alone. Our florivory study demonstrated marginally significant increased emission rates of two individual
volatile compounds (E) and (Z)-?-ocimene in Biscutella flowers, in response to Plutella feeding. Our results suggest a
relative importance of olfactory and visual signals in attraction of the predatory crab spiders to locate their preys.
Moreover, we hypothesize that the increased emissions of these volatile compounds could be linked to attraction
of natural enemies of the herbivore, or alternatively to increase attraction to pollinators to compensate for the
damage caused by the herbivores.
53
Are the Coastal Forests of Eastern Africa a source of species diversity?
Chris Barratt, [email protected], University of Basel; Simon Loader, [email protected],
University of Basel; Peter Nagel, [email protected], University of Basel
The Coastal Forests of Eastern Africa (CFEA) are one of the most threatened biodiversity hotspots in the world. The
distribution of biodiversity and how it accumulated in this hotspot is poorly known. In particular, it is unclear
whether the present distribution of diversity is mainly: a) The result of recent colonisation from adjoining refugial
areas (Eastern Afromontane Region, EAR) due to habitat instability and inundation of the CFEA, or b) the result of
radiations from relicts within CFEA which have persisted in suitable climatically stable environments. To test these
questions we are mapping the distribution of Phylogenetic Endemism, and combining this with with demographic
analyses based on next generation sequencing (NGS) data. Analyses suggest that diversity is heterogeneously
distributed and often corresponds to areas of relative climate stability. Our results indicate that while parts of the
CFEA may be a source area of diversity, significant colonization from the EAR contributes to its diversity.
Contrasting variation in sexual and flight morphology with spatial patterns of neutral genetic
differentiation in two widespread sister species of sepsid flies (Diptera: Sepsidae)
Julian Baur, [email protected], University of Zurich; Athene Giesen, [email protected], University of
Zurich; Martin A. Schaefer, [email protected], University of Zurich; Wolf U. Blanckenhorn,
[email protected], University of Zurich
Speciation requires the evolution of reproductive barriers, and may involve sexual selection, environmental
adaptation or stochastic demographic processes.
We address these issues by contrasting morphological and (presumably neutral) genetic variation among multiple
European populations of Sepsis cynipsea and both, European as well as North American, populations of its close
relative S. neocynipsea. We compare patterns of shape variation in the armored male foreleg femur, a secondary
sexual trait involved in sexual competition and conflict, with morphological variation in wing vein positioning. Ten
microsatellite loci are used as neutral phylodemographic background against which the role of adaptive
diversification can be evaluated.
Although forefemur showed a higher degree of differentiation than wing morphology, its differentiation was not
stronger in areas of sympatry than allopatry, suggesting that reinforcement is not an important driver for shaping
sexual trait divergence. Rather our data showed a strong phylodemograpic signal, indicating significant drift effects.
Within species we find strong differentiation of both morphological traits among populations, which are in striking
contrast with the low (albeit statistically significant) degree of differentiation inferred by microsatellite analysis.
Our findings imply that different evolutionary processes contribute to long-term and short-term evolutionary
patterns of trait divergence.
54
Genetics of Daphnia magna resistance to a pathogen
Gilberto Bento, [email protected], Basel University; Peter Fields, [email protected], Basel University;
Jarkko Routtu, [email protected], Martin Luther University - Halle; Yann Bourgeois,
[email protected], Basel University; Dieter Ebert, [email protected], Basel University
Daphnia magna is a model organism for studies in host-pathogen coevolution. In recent years a body of evidence
was built that shows that the host-pathogen system composed of D. magna and its bacterial pathogen Pasteuria
ramosa empirically fulfills all requirements for evolution by negative frequency-dependent selection, also called
Red Queen theory. Furthermore, one locus was identified that is associated to D. magna resistance to P. ramosa,
specifically, to resistance to infective spore attachment to the hosts’ foregut. We used whole genome DNA and
RNA sequencing approaches to identify and characterize genetic and gene expression polymorphisms between two
alleles of one locus that are associated to resistance and susceptibility to one P. ramosa genotype. We found that
the two alleles display extensive structural polymorphisms with sequences that have no detectable homology
between them. Moreover, gene content is altered between resistance and susceptibility-associated alleles.
Interestingly a cluster of glycosyltransferase genes has a higher number of homologs in the susceptible allele and
we found that glycosyltransferases are generally downregulated in the resistant clones. We also explore an
alternative infection mechanism of D. magna by P. ramosa - spore attachment to the hosts’ hindgut. We found that
resistance to this alternative infection mechanism in D. magna is underlined by two unlinked loci. We are currently
investigating the underlying genetic and molecular mechanisms.
The genomic basis of resistance evolution to a fungicide in populations of a fungal barley pathogen
Norfarhan Binti Mohd Assaad, [email protected], ETH Zurich; Daniel Croll, [email protected],
ETH Zurich
Fungi are major pathogens of plants and animals including humans. Fungal diseases in agro-ecosystems are
particularly challenging, because natural resistance of crops is generally poor. The application of fungicides such as
azoles is able to prevent major epidemics, however the continuous use of fungicides imposed strong selection
pressure on the pathogens populations to evolve fungicide resistance. Fungal pathogens evolved resistance to all
fungicides approved for use in agriculture within the span of a decade. Hence, identifying the mechanisms by which
resistance evolved repeatedly will be important to formulate more durable control strategies. We used wholegenome resequencing and genome-wide association studies (GWAS) to identify the genetic basis of azole fungicide
resistance in Rhynchosporium commune, the causal agent of the barley scald disease. We assayed cyproconazole
resistance in 125 R. commune isolates from 9 populations spanning the worldwide distribution of the pathogen.
We found that the strongest contributions to fungicide resistance were not found in the only previously known
azole resistance gene CYP51, but included mutations in highly conserved genes encoding for a vacuolar cation
channel and a transcription activator. These two genes were not previously implicated in fungicide resistance,
however the vacuolar cation channel was found to control a conserved stress response pathway that is known the
be involved in the response to fungicides. We asked whether mutations in the two genes were having pleiotropic
effects. For this, we performed GWAS on fungal growth rates. We found that the mutation in the transcription
activator was negatively impacting growth which suggests that fungicide resistance is costly and involves a tradeoff. Mutations in the genes encoding the vacuolar cation channel and the transcription activator likely evolved
independently in two unrelated populations sampled in Switzerland and New Zealand.
55
Myrmicinosporidium durum: An enigmatic ant disease appears in Basel
Brigitte Braschler, [email protected], University of Basel
Ants fulfill central roles in many ecosystems as soil ecosystem engineers but also as a group that interacts with
many other taxonomic groups. While many aspects of ant biology are relatively well studied, very little is known
about ant diseases and their impact on infected colonies. An enigmatic disease is Myrmicinosporidium durum, an
endoparasitic fungus reported so far from 38 ant species in Europe and America. Despite this wide range of hosts
and wide geographic range, M. durum has been only infrequently reported since its discovery in 1927, and very
little information is available on its biology or the impact it has on its hosts. In 2014 ants infested with M. durum
were found in a survey covering 49 sites distributed over urban and rural areas in the Canton Basel-Stadt. Sampling
was done repeatedly over the active season using pitfall traps. The persistence of the disease in the most
frequently infected species Solenopsis fugax could be confirmed in autumn of the following year in a targeted subsample of sites. This poster reports first results on the distribution of M. durum in the study region, on which ant
species were infected, and on differences in infection rates over the season.
FROZENFIRE - vegetation and fire dynamics from high-alpine ices cores
Sandra Brugger, [email protected], University of Bern; Erika Gobet, [email protected],
University of Bern; Michael Sigl, [email protected], Paul Scherrer Institute; Dimitri Osmont,
[email protected], Paul Scherrer Institute; Daniele Colombaroli, [email protected], University
of Bern; Margit Schwikowski, [email protected], Paul Scherrer Institute; Willy Tinner,
[email protected], University of Bern
Wild fires are an ecological disturbance agent across ecosystems worldwide, driving vegetation dynamics and
biomass availability. In recent years, devastating, uncontrolled fires have increasingly occurred on all vegetated
continents, resulting in enormous economic costs and disruption of habitats (1). Pollen and spores as proxies for
vegetation composition, structure and agricultural activity, microscopic charcoal (>10µm) as a proxy for fire activity,
and framboid organic particles (or soots) as a proxy for fossil fuel combustion preserve in ice cores over millennia
(2). We use an existing ice core from Colle Gnifetti in Switzerland (4450 m a.s.l.) with an excellent chronological
control, particularly over the last 150 years to assess vegetation and societal responses to climatic change and
wildfire disturbance for the past centuries ??? the period that experienced important climatic changes and an
increasing globalization of economy. Our record contributes to test the “broken fire hockey stick”-hypothesis (i.e.
an unproven global decline of fire activity during the past decades). In particular we aim at disentangling the role of
climate, vegetation and human impacts on biomass burning in the Mediterranean realm and Europe to significantly
advance the understanding of the regional role of wildfire events and vegetation responses under future climate
change scenarios.
References
1) Moritz M. A., Batllori E., Bradstock R. A., Gill A. M., Handmer J., Hessburg P. F., Leonard J. McCaffrey S., Odion D.
C., Schoennagel T., Syphard A. D. (2014): Learning to coexist with wildfire. Nature, 515(7525), 58-66.
2) Eichler A., Tinner W., Brütsch S., Olivier S., Papina T., Schwikowski M. (2011): An ice-core based history of
Siberian forest fires since AD 1250. Quaternary Science Reviews, 30(9), 1027-1034.
56
Intraspecific variation in plant chemical defenses along elevation gradients in two Alpine Brassicaceae
species
James Buckley, [email protected], ETH Zürich
Variation among species in the rate at which they are responding to climate change is driving shifts in the
composition of local communities. Plants, for example, tend to be slower to move to higher latitudes and
elevations, whereas the insects with which they interact are showing some of the fastest distributional shifts. In
alpine environments, it is predicted that diversity of invertebrates will increase at higher elevation, which will result
in local plant populations having to interact with a novel set of pollinators and herbivores. An important question is
therefore whether alpine plants at high elevation are able to adapt this changing biotic environment. However, to
understand this question, we first need to determine the extent of existing adaptive variation in key traits along
altitudinal gradients. Recent empirical evidence suggests that damage by invertebrate herbivores decreases with
elevation, which may select for lower investment in defense against herbivores at higher elevation. I will test this
hypothesis using two Brassicaceae species, Arabidopsis halleri and Arabis alpina. Both species show distributions
from 800m to >2000m in the Swiss Alps occupying a range of heterogeneous habitats. I will examine patterns of
leaf damage along these gradients, and test for reduced investment in both constitutive and herbivore-induced
plant defenses in high elevation populations. Specifically, I will assay concentrations of phytohormones involved in
defense signalling pathways, as well as patterns of herbivore-induced organice volatiles, and test for associations
with respect to altitude and other environmental factors.
Modeling soil water content for vegetation modeling improvement
Carmen Cianfrani, [email protected], University of Lausanne; Aline Buri, [email protected], University of
Lausanne; Pascal Vittoz, [email protected], University of Lausanne; Barbara Zingg, [email protected],
University of Lausanne; Antoine Guisan, [email protected], University of Lausanne
Soil water content (SWC) is known to be important for plants. It affects the physiological processes controlling plant
growth. SWC therefore controls the distribution of plants over the earth surface, ranging from deserts and
grassland to rain forests. Unfortunately SWC measures are very time consuming and costly to obtain, needing of
specific laboratory tools for analyses. As consequence few measures are available making it difficult to model over
larger areas. It prevents its inclusion in plant SDMs. Our aims were to test a new methodology that allowed us to
overpass the problems of having few SWC measures to model it. The final goal was to assess plants SDMs
improvement with the inclusion of SWC parameter.
Firstly we modeled SWC measured at 10 different pressures (expressed in pF and ranging from pF 0 to pF 4.2). The
different pF represents different degrees of soil water availability for plants. We built bivariate models to overpass
the problem of having a small number of SWC measures (n = 24) and several predictors to include in the model. We
used as predictors 3 classes of soil texture, organic matter (OM) and topo-climatic variables. We selected bivariate
models with R2adjusted > 0.5 to built weighted ensemble models for SWC at different pF. We then assessed the
improvement in plant SDMs by adding to the usually topo-climatic factors the SWC.
In general, ensemble models were very good with an R2adjusted ranging from 0.55 to 0.65. Bivariate models with
higher performance used as predictors OM, aspect and convexity.
We found that adding SWC improves the vegetation models. It improves 51%-64% (depending on pF) of plant
species SDMs. In this study we showed that important information is still missing in SDMs to capture all abiotic
drivers of plant species distributions.
57
Responses of demographic rates to body mass: mass affects probability to breed but not breeding
success in the wandering albatross
Tina Cornioley, [email protected], University of Zurich
Investigating how species respond to their environment is critical to predict their reaction to change. If fitnessrelated traits are impacted, species may become locally extinct or, in contrast, proliferate depending on the
direction of the change. Here I investigated how a plastic phenotypic trait impacted by climate change affects key
life-history processes of a long-lived species. The wandering albatrosses population breeding on the Crozet Island
has been reported to increase in mass in parallel to increasing wind speed and breeding success. I assessed the
effect of mass on survival, breeding probability and breeding success. I found that mass affects probability to breed,
but neither breeding success nor survival. This is consistent with long-lived species strategy: long-lived species can
sustain high residual reproductive value for longer and therefore invest resource mostly into survival and engage in
reproduction only when conditions are favourable. This study underlines the importance of considering phenotypic
traits when predicting population trajectories under environmental changes. As mass impacts at least one lifehistory rate and is predicted to increase with increasing wind speed, the next step is to assess how a climate-driven
change in this trait can affect the dynamic of the population and the distribution of this trait within the population.
Molecular diversity and biogeography of the Thraulus lineage (Leptophlebiidae) in New Guinea
Camille-Sophie Cozzarolo, [email protected], University of Lausanne; Nadir Alvarez,
[email protected], University of Lausanne; Michel Sartori, [email protected], Musée de Zoologie de
Lausanne
Tropical regions are the most biologically diverse, but they also appear among the most endangered ecosystems.
Yet, they are still vastly underexplored. New Guinea in particular shows a high diversity of climates and landzones.
Here we present new results on the diversification process of New Guinean lineages, using a large mayfly
(Ephemeroptera) sampling. Among the specimens collected, the Leptophlebiidae, and in particular the Thraulus
group, drew our attention on their astonishing morphological diversity. The aim of this work was to investigate the
monophyletic nature of the Thraulus group and to produce a dated molecular phylogeny based on mitochondrial
genes (16S and COI). We also inferred the biogeographic scenario of the group in order to determine the
evolutionary history that took place in New Guinea. We found that the Thraulus lineage is recovered as
monophyletic (PP = 1). Our results suggest the existence of up to 35 putative species in the Thraulus lineage—and
thus question the plasticity of the morphological traits currently used for taxonomic identification. Colonization of
Papua New Guinea by the Thraulus clade is likely to have occurred during the Eocene, proceeding from the Eastern
Papuan Peninsula towards the west of the island. Eventually, most lineages have experienced recent ecological
shifts towards higher elevation habitats, a result compatible with the recent New Guinean orogenesis.
58
Plant defense syndromes along elevation gradients
Emmanuel Defossez, [email protected], University of Neuchatel; Pellissier Loïc,
[email protected], ETHZ; Rasmann Sergio, [email protected], University of Neuchatel
Ecological theory indicates that warmer and more stable climates should result in stronger biotic interactions.
Therefore, plant species growing at lower elevations and experiencing greater herbivore pressure, should invest in
higher levels of defenses than those at higher elevations. However, there are a number of studies that have found
no effect of elevational gradients on plant defensive traits or even inverse patterns. These contradictory results
could be partially explained by the fact that the large majority of studies are focusing on one or few defensive trait
at once, while in reality, plant defense strategies should be considered as a matrix-like simultaneous expression of
several traits, including physical barriers, toxic or anti-nutritive secondary metabolites, and/or recruitment of
predators and parasitoids. We here addressed whether plants growing at different elevations are selected to
deploy different defense syndromes, each adapted to a particular growing habit and herbivore pressure.
We analysed the simultaneous expression of several growth-related and defense-related traits across 16
Cardamine species naturally growing in the Alps. Using functional niche modeling, multivariate analysis, radial plot
geometry and hypervolume analyses we were able to describe three specific syndromes related to low middle and
high elevation plant species. Specifically, our results show that high elevation species invest more in constitutive
toxic metabolites production and tougher leaves, while at low elevation, plants tend to be more palatable, bigger
and more inducible for defenses related to toxicity and predator recruitment. Using the syndrome approach allows
a more dynamic understanding of how plant adapt to different biotic and abiotic environments, and sheds further
light for understanding how species interactions are shaped in nature.
ecospat: an R package for the support of spatial analyses and modelling of species niches and
distributions
Valeria Di Cola, [email protected], University of Lausanne; Olivier Broennimann, [email protected],
University of Lausanne; Blaise Petitpierre, [email protected], University of Lausanne; Frank T. Breiner,
[email protected], University of Lausanne; Manuela D’Amen, [email protected], University of Lausanne;
Christophe Randin, [email protected], University of Lausanne; Robin Engler, [email protected], SIB;
Julien Pottier, [email protected], INRA; Anne Dubuis, [email protected], University of
Lausanne; Loic Pellissier, [email protected], University of Fribourg; Dorothea Pio, [email protected], Fauna &
Flora International; Nicolas Salamin, [email protected], University of Lausanne; Rubén G. Mateo,
[email protected], University of Lausanne; Wim Hordijk, [email protected], University of
Lausanne; Antoine Guisan, [email protected], University of Lausanne
The ‘ecospat’ package brings together tools and methods to complement various existing analyses in spatial
ecology, with a particular focus on pre- and post-analyses of species distribution models, niche quantification and
community assembly. The package is written in the R language and contains several unique features. In particular,
pre-modelling analyses include species niche quantifications and comparisons between distinct ranges or time
periods, predictions of phylogenetic diversity, and other data exploration functionalities (e.g. multivariate
environmental similarity surfaces, MESS). Post-modelling analyses include predictions of community composition
and environmentally-constrained species co-occurrences analyses. The package also provides some functions to
complement the biomod2 package (e.g. data preparation and various evaluation techniques including the Boyce
index for presence-only models, permutation tests and cross-validation of model predictive power). With this novel
package we intend to strengthen the development and use of comprehensive and interdisciplinary approaches in
spatial ecology.
59
Assessing diversity and evolutionary dynamics in a postglacial radiation of whitefish
Carmela Doenz, [email protected], eawag and University of Bern; Ole Seehausen,
[email protected], eawag and University of Bern
Endemic species diversity is one of the hallmarks of intact lake ecosystems, and its protection is of major concern.
This requires understanding how diversity is generated, maintained, and lost, which is however only possible when
diversity is first recognized. Young and diverse taxa pose a special challenge: first, there are many and often
difficult-to-distinguish species, and second, as reproductive isolation may be incomplete and rely on extrinsic
barriers, young species are not only threatened with extinction through population decline, but also rely on
environmental conditions to maintain species boundaries.
This study focuses on the young, postglacial whitefish diversity of two deep, formerly connected pre-alpine lakes
that harbor one of the largest Swiss whitefish radiations, Lakes Thun and Brienz. Previous studies on this system
assessed variation of known whitefish species, collected by targeted sampling on known spawning grounds.
However, species discovery and delimitation is limited with this approach.
Here we combine microsatellite genotypic data of more than 2000 individual whitefish obtained from samplings
targeted to known species on known spawning grounds as well as from taxonomically unbiased, random samplings
covering the entire lake ecosystem. This enables us to detect unknown, possibly rarely caught whitefish species,
and provides detailed insights into how intra- and interspecific genotypic variation is structured in one of the
largest lacustrine Swiss whitefish radiations. Furthermore, by comparing genetic diversity in contemporary and
historical whitefish samples, we found support for the recent establishment of an introduced whitefish species in
one of the lakes, and its continued coexistence with the species of the local radiation. Using genotypic and
morphological data, we assess the evolutionary and ecological effects of this introduction on the radiation
assemblage, which may ultimately allow for a better understanding of the evolutionary ecology of whitefish
radiations in pre-alpine lakes.
Natal Dispersal of Eurasian lynx in Switzerland: comparing camera trapping with telemetry
Nicolas Dulex, [email protected], University of Lausanne; Fridolin Zimmermann, [email protected], KORA
In most mammals natal dispersal is expected to follow a male-biased dispersal pattern, while in the genus Lynx
telemetry studies revealed contradictory findings. Here, we tested whether photographic data collected since 1998
in Switzerland can be used to study natal dispersal of naturally marked species compared to telemetry. Dispersal
distance and direction were investigated in three reintroduced Eurasian lynx populations (Jura Mountains, Swiss
Alps and north-eastern Swiss Alps) using different photographic data sources: deterministic (i.e. data from
photographic capture recapture studies in selected reference areas), opportunistic (i.e. data from camera traps
placed opportunistically at fresh kills or along trails) camera trapping and photographs collected by chance and
both data sets combined. According to our results dispersal distances estimated from photographic data were
comparable to those resulting from telemetry (ANOVA, F=0.111, df=1, P=0.739). Lynx in the Jura Mts. dispersed
farther than those from the Alps irrespective of which data set was considered. Male-biased dispersal pattern
occurred in the Jura Mts. only and was revealed by the opportunistic camera trapping and the full data sets.
Models including population density in the area of origin were not retained leading to the conclusion that density
did not affect dispersal distance in this study. While dispersal directions were randomly distributed in the Alps,
these were biased toward the south-west and north-east in the Jura Mts. corresponding approximately to the
orientation of the predominant ridgelines of this mountain range. The lower distances performed in the Alps are
probably related to the size and arrangement of suitable habitat in each area as well as linear barriers.
Opportunistic camera trapping allowed a broader spatial coverage and a higher recovery rate of individuals who
left the deterministic camera trapping reference areas. The study of dispersal distance and direction of naturally
marked individuals by means of camera trapping is possible given that data from long-term camera trapping studies
are available and cover the largest existing surface to increase the sample size and thus the statistical power.
60
A comparative analysis of egg-dummy related genes in East African cichlid fish
Natacha Espirito Santo, [email protected], Zoologisches Institut, Universität Basel; Langyu Gu,
[email protected], Zoologisches Institut, Universität Basel; Walter Salzburger, [email protected],
Zoologisches Institut, Universität Basel
The cichlid fishes of the East African Great Lakes are famous for their adaptive radiations and great phenotypic
diversity. They appear in many different colors, shapes and feature varied mouth morphologies in relation to
different feeding strategies. One of the remarkable traits of several cichlid lineages, including the most species-rich
group of cichlids (the haplochromines), are anal fin egg-dummies. These pigmentation patterns occur in the form of
spots or blotches on the anal fin of males. Different studies suggest that these egg-dummies play a role in female
choice as well as in male-male interactions. In this study we examine, at the molecular level, a set of candidate
genes for egg-dummie development identified in an earlier experiment. To this end, we used a representative set
of East African cichlids - some expressing the egg-dummies and some not - to study the molecular evolution of
these genes and to identify features restricted to the lineages displaying egg-dummies.
Dead wood stems artificially inoculated with a hypovirulent Cryphonectria parasitica strain for an
efficient biocontrol of chestnut blight
Fabio Fässler, [email protected], ETH Zürich; Joana Meyer, [email protected], Swiss Federal Research
Institute WSL; Simone Prospero, [email protected], Swiss Federal Research Institute WSL; Daniel Rigling,
[email protected], Swiss Federal Research Institute WSL
Cryphonectria parasitica, the causal agent of chestnut blight, is one of the most important fungal pathogens of
European chestnut (Castanea sativa) in Europe. Chestnut blight can be biologically controlled by a virus (CHV-1)
that infects the fungus and reduces its virulence and sporulation. At the epidemic front of the disease, only the
aggressive (virulent) form of the pathogen is generally observed. Therefore, the virus is frequently artificially
introduced into diseased chestnut stands. For this, multiple holes are produced around virulent bark lesions
(cankers) and filled with a virus-infected fungal mycelium. The virus may then spread to the virulent canker
potentially healing it. This laborious treatment is usually successful for the target cankers, but, because of the lack
of sporulation on the treated cankers, may not result in a dynamic, self-spreading CHV-1 population. In this study,
we tested a new method for introducing CHV-1 into blighted chestnut stands. As virus-infected C. parasitica strains
sporulate stronger and produce a higher amount of virus-infected spores on dead wood than on living chestnut
trees, dead chestnut stems were inoculated in the laboratory with a virus-infected C. parasitica strain. After
complete colonization, the stems were attached to chestnut trees harboring virulent C. parasitica cankers, either
above or below the canker. After twelve months, about 70% of the cankers were infected with the virus. Infection
rate was significantly higher when the dead wood was placed above the target canker. This experiment shows that
the use of dead chestnut stems artificially inoculated with virus-infected strains of C. parasitica may be a promising
new method for successfully controlling chestnut blight.
61
The influence of browsing exclusion on the performance of the relict tree Zelkova abelicea (Ulmaceae)
and its communities in the mountains of Crete (Greece)
Laurence Fazan, [email protected], University of Fribourg; Marie Beffa, [email protected], University of
Fribourg; Gregor Kozlowski, [email protected], University of Fribourg
Zelkova abelicea (Lam.) Boiss. (Ulmaceae) is a Paleogene relict and the only endemic tree species growing on the
island of Crete (Greece). The species is classified as endangered on the IUCN red list of threatened species. Only
several hundreds of reproducing trees are still found in the mountains of Crete. The species has a strong scientific
as well as patrimonial value since traditional shepherd sticks (katsounes) are also made from its durable wood.
Browsing and trampling by goats and sheep is by far the most important threat to the growth, reproduction and
survival of individuals. An integrative conservation project including in-situ, ex-situ measures and public awareness
actions was launched in 2013 to help protect this species. As part of the in-situ measures, 15 plots containing Z.
abelicea individuals were fenced in autumn of 2014 in order to remove the browsing pressure. Subsequent
monitoring of individual growth as well as species richness and vegetation cover was undertaken, and the situation
within the non-browsed plots was compared with areas still subject to browsing.
We present here the first results obtained after one year of fencing. Species richness and vegetation cover were
higher within the non-browsed plots compared to areas still subject to browsing. Moreover, intensive primary
growth was observed in Z. abelicea individuals already during the first spring after fencing. These findings confirm
and help to quantify the strong influence that browsing may have on the local plant communities and suggest the
speed and trend of vegetation response to browsing removal.
Species diversity and morphological stasis in skates (order Rajiformes): the challenge of skin
transcriptome profiling in non-model species
Alice Ferrari, [email protected], University of Bologna; Walter Salzburger, [email protected],
University of Basel; Robert Leslie, [email protected], Dept. of Environmental Affairs & Agriculture, Forestry
and Fisheries of Cape Town; Giuseppe Scarcella, [email protected], CNR - Ismar; Alessia Cariani,
[email protected], University of Bologna; Fausto Tinti, [email protected], University of Bologna
Approximately twenty years have passed since the beginning of concentrated investigations into the evolutionary
history and ecology of skates. The evidence generated thus far suggests that skates have experienced multiple and
parallel adaptive radiations at a regional scale, starting in the upper Cretaceous, which contributed to the
delineation of strong phylo-geographical and population structuring. Despite the high species diversity
characterising the Order Rajiformes, a strikingly stable gross morphology has been maintained on the evolutionary
level. The combined use of morphometric analyses and genotyping by various panels of molecular markers on a
large number of samples of widely distributed and endemic geographic populations provided efficient tools for
stock identification and management. Nonetheless, the adaptive value of some phenotypic traits as, for instance,
particular ornaments of the dorsal part of the body, remains poorly understood. Here, we applied transcriptome
profiling of skin pictorial motifs (eyespots and dots on a uniformly coloured matrix) on recently diverged species
with sibling and sister phylogenetic relationships (Raja clavata, R. straeleni and R. asterias respectively) and on
species that are easily recognized by specific patterning traits and show strong monophyly (the Mediterranean R.
miraletus and the South African R. ocellifera). The on-going differential expression analysis at skin transcriptome
level will help to understand mechanisms of divergence, hybridisation signals and could be considered one of the
tiles allowing to evaluate whether the same or alternative traits have been used in parallel adaptations to similar
environments.
62
Ant workers from single-queen colonies do not attack additional queens
Amaranta Fontcuberta, [email protected], University of Lausanne; Michel Chapuisat,
[email protected], University of Lausanne
The number of breeders per group profoundly affects the kin structure of animal societies, yet the behavioural
processes controlling this trait remain poorly understood. In the Alpine silver ant Formica selysi, colonies with one
queen and colonies with multiple queens coexist in the same populations. All single-queen colonies have a
diagnostic genotype at a supergene, suggesting that their social structure is stable over time, and that these
colonies do not gain additional queens. This pattern might be explained by aggression of workers towards young,
newly mated queens trying to join the colony. Here, we present a pilot study testing whether workers from singlequeen colonies reject mated queens introduced experimentally in their colony. First, we show that when workers
aggress introduced queens, these queens die within twelve hours. Second, workers are more aggressive towards
foreign queens (10 out of 21 cases) than towards nestmate queens (2 out of 23 cases). In field and laboratory
assays, workers from single-queen colonies show little aggression towards additional queens from the same colony.
Overall, our results suggest that workers from single-queen colonies do not discriminate against additional mated
queens, at least in the conditions tested. This raises new questions on the mechanism maintaining the social
structure of single-queen colonies in natural populations of Formica selysi.
Effects of wastewater treatment plant effluents on freshwater bryozoans hosts to a myxozoan parasite
causing salmonid proliferative kidney disease in Switzerland
Mélanie Guillebeau, [email protected], eawag; Inês Fontes, [email protected], eawag; Hanna
Hartikainen, [email protected], eawag
Wastewater treatment plant (WWTP) effluents are a major source of chemicals, microbes and temperature
increases in freshwater ecosystems. These effluents have been shown to directly impact e.g reproduction and
development and cause shifts in community structure and functioning. Here we test how effluents from WWTP
may impact complex host-parasite interactions. Proliferative kidney disease (PKD) is a disease of salmonid fish,
caused by Tetracapsuloides bryosalmonae (Tb), which exploits freshwater bryozoans as primary hosts [mainly
Fredericella sultana (Fs)]. A field survey upstream and downstream from 24 WWTPs across Switzerland was used to
assess the occurrence of the bryozoan host and the parasite. The effects of WWTP effluents on host growth and
reproduction were measured using a lab experiment. Bryozoans were exposed to three treatments: river water
only, 70% of river water mixed with 30% effluent and 30% of river water mixed with 70% effluent, implemented in
artificial river systems (flumes). We also tested for a genetic basis of the bryozoan response to WWTP effluents by
tracking the traits of several clonal bryozoan lines in a lab experiment. The field surveys revealed that 42% of sites
contained Fs populations and 60% of these populations displayed virulent infection stages (i.e. at least 25% of all
sites contained Tb). The abundance of bryozoans was significantly higher downstream than upstream from WWTPs
within the sites that contained at least some bryozoans. In the lab experiment, the survival of bryozoans was
significantly increased by addition of WWTP effluent. No differences in survival were detected between different
bryozoan clones (n = 8). These results suggest that WWTPs are associated with increased bryozoan abundance,
thus providing more susceptible host material for parasite exploitation. Downstream regions of WWTPs may
therefore function as hotspots of infected bryozoans, which produce proportionately more infective spores to fish.
Whether salmonid populations suffer from increased PKD due to such local dynamics is a subject of further study.
63
Large-scale detection of chromosomal abnormalities following meiosis in a fungal pathogen of wheat
Simone Fouche, [email protected], ETH; Daniel Croll, [email protected], ETH
Chromosomal rearrangements drive genome evolution and have been reported throughout the domain of
eukaryotic life. Errors occurring during meiosis or mitosis can result in chromosomal abnormalities. For example,
the non-disjunction of sister chromatids can cause chromosome number polymorphism. In humans aneuploidy is
associated with several congenital disorders including trisomy 21 (Down syndrome). Genomic rearrangments, such
as chromothripsis or localized chromosome shattering and repair, have been shown to play a role in cancer
development. In contrast, in crops chromosomal abnormalities can be associated with a desirable trait, for example
triploid bananas that do not produce seed. Chromosome polymorphism is particularly abundant in fungi including
Zymoseptoria tritici, an important pathogen of wheat. The fungus has 13 core chromosomes required for growth
and development, and between one and eight rapidly evolving accessory chromosomes that are non-essential and
frequently undergo rearragements. We developed a method to screen a large number of offspring for chromosome
diversity by using restriction-site associated DNA sequencing (RAD-seq) obtained for 500 offspring from two
different crosses. Coverage of Illumina reads mapped to a reference genome was used to predict duplications,
deletions and the occurrence of disomic chromosomes among offspring. As expected, we found that accessory
chromosomes exhibited much more diversity in terms of inheritance or loss of chromosomal regions than the core
chromosomes. Next, we calculated divergence levels between homologous accessory chromosomes of the parental
strains. We assessed both the length difference and the extent of indel polymorphism between the parental
homologs. We then related diversity measures of the parental homologs to the frequency of chromosomal
abnormalities detected among offspring. Our study contributes towards developing models to predict factors
impacting the fidelity of chromosomal transmission through meiosis. Large-scale chromosomal inheritance studies
will improve our understanding of the mechanisms whereby chromosome rearrangements occur.
Patch-level woody vegetation cover drives pest control by birds in dense urban areas
David Frey, [email protected], Swiss Federal Research Institute WSL; Kevin Vega, [email protected], University
of Zurich; Annette Stephani, [email protected], University of Zurich; Jaboury Ghazoul,
[email protected], ETH Zurich; Dennis Hansen, [email protected], University of Zurich; Marco
Moretti, [email protected], Swiss Federal Research Institute WSL
Urbanization, i.e., the increasing proportion of humans living in cities, is one of the major drivers of global land-use
change and is currently accelerating at an unprecedented pace. Although the importance of investigating the
impacts of urbanization on plant and animal communities is widely recognized, important knowledge gaps still
remain. For instance, the relative importance of landscape- and patch-level drivers of ecosystem functioning and
underlying services remains poorly understood. In this study, we assessed the predator activity of birds on potential
pest arthropods using plasticine artificial caterpillars as prey models. This assessment was conducted in 18 private
gardens in the city of Zurich, Switzerland, along two gradients of woody vegetation cover: a) within garden patch
and b) within a 100 meter radius around each garden. A total of 643 artificial caterpillars were examined for traces
of bird predation, and generalized linear mixed effect models revealed a significant interaction between gardenand landscape-scale woody vegetation cover. Gardens with abundant woody vegetation located within the densely
built-up and sparsely vegetated city center were found to have a significantly higher predation rate than gardens
with either similar levels of woody cover within green residential areas or gardens with few shrubs and trees in
general. Our results indicate the existence of a crowding effect on urban birds in resource rich habitat patches
when surrounded by a resource poor landscape, and supports the hypothesis of wildlife friendly gardens as
important resource islands in dense urban areas.
64
Tackling niche evolution of alien plant species during invasions from an alpine botanic garden
Aurore Gaille, [email protected], University of Lausanne; François Bonnet, [email protected], Musée et
Jardins Botaniques Cantonaux, Lausanne; François Felber, [email protected], Musée et Jardins Botaniques
Cantonaux, Lausanne; Christophe Randin, [email protected], Musée et Jardins Botaniques Cantonaux,
Lausanne
Botanical gardens have provided some of the best-documented examples in which alien species have escaped,
spread and given rise to invasions, potentially causing threats to biodiversity, economy and human health.
Three plant species have escaped from the Alpine botanic garden of La Thomasia in Pont-de-Nant (Bex,
Switzerland) since 1896: Heracleum mantegazzianum, Telekia speciosa and Valeriana alliariifolia.
Here we assessed the impact of these three alien plants on local diversity and characterize for the first time the
micro-climatic niche of the three invasive plants for comparisons with their macro- and local-scale climatic
requirements.
Predicting effects of multiple environmental changes on dissolved oxygen in a microcosm experiment
Aurélie Garnier, [email protected], University of Zurich; Owen Petchey, [email protected],
University of Zurich
Predicting the ecological consequences of changing environmental conditions is a challenge for ecologists,
especially when multiple environmental conditions change simultaneously. If changes in multiple environmental
conditions have additive effects, then predicting their consequences will be relatively straightforward. If, however,
interactions among environmental changes are common and strong relative to their individual effects, prediction
will require some method of quantifying these interactions.
While some evidence suggests that interactions between different environmental changes are important (Darling &
Côté 2008, Crain et al. 2008, Sala et al. 2000), this is mostly restrained to studies of changes in two or three
environmental conditions. We studied the effect of press changes in four environmental conditions, in a fullyfactorial experiment using microbial aquatic ecosystem containing algae, bacteria, ciliates and rotifers.
Environmental conditions were: temperature, inorganic nutrient supply, organic carbon supply and light
availability.
We measured the response of dissolved oxygen concentration, an important ecosystem property of aquatic
communities. We estimated short- (resistance), medium- (resilience), and long-term (return time) responses to the
press perturbation. Increases in the number of perturbations, from one to four, were associated with decreased
resistance, increased return time and no effect on resilience.
Moreover we tested three hypotheses (additive, interactive, dominant [the combined effect of multiple
environmental changes equals the size of the largest individual effect]), and compared the predictions to the
observations to assess the predictability of the response to multiple environmental changes.
Overall, short-term (resistance) predictability was better than medium- and long-term predictability, and the
interactive hypothesis gave the best adjusted R2. Using simplest hypotheses, the additive hypothesis had a better
predictability for the resistance and return time, whereas the dominant hypothesis was the best predictor for the
resilience. Despite the lack of significant interactions, and high explanatory power of additive and dominant
hypotheses, predictions based on these would consistently underestimate multiple environmental effects, due to a
dominance of negative interaction effect sizes.
These insights will assist the development of better models for predicting effects of multiple environmental
changes on ecological systems for medium- and long-term responses.
65
Host-parasite specificity in bat mixed-species colonies: is the bent-winged bat Miniopterus schreibersii
really unique?
Eléonore Genzoni, [email protected], Université de Lausanne
One of the most fundamental properties of host-parasite association is the degree of host specificity. Specificity is
commonly believed to be the result of an adaptive process, however the mechanisms underlying the evolution of
host specificity are still not fully understood. The common bent-winged bat Miniopterus schreibersii is a highly
gregarious cave-dwelling species, in which high host-parasite specificity has already been demonstrated, such as
the haematozoan parasite Polychromophilus melanipherus and its vector, the bat fly Nycteribia schmidlii. Host
specificity in parasites may result either from spatial isolation from other potential hosts or from fixed coevolutionary host-parasite adaptations. In addition to form colonies of several thousands individuals, M.
schreibersii is found in mixed-species colonies and the proximity between individuals might increase parasite
exchange. To assess the spatial isolation hypothesis to explain host-parasite specificity between M. schreibersii and
its blood parasites, we sampled 273 bats (from six species) including 147 M. schreibersii individuals, from mixedspecies colonies, in four Mediterranean countries. We examined the relationship between bat species composition
within colonies and the parasites presence in individuals of different species. Our results suggest that M.
schreibersii is unique in several ways. First, Trypanosoma livingstonei, a parasites identified for the first time in
Europe in 2014, has only been identified in M. schreibersii individuals, despite spatial proximity between the
different bat species. A high host specificity of the blood parasite P. melanipherus and the bat fly vector N. schmidlii
was also found, suggesting a long evolutionary history. Second, M. schreibersii showed a higher prevalence of both
Trypanosoma and Polychromophilus than the other bat species. Finally, we discovered an effect of
Polychromophilus infection on the body length of the mouse-eared bat Myotis myotis, where infected individuals
are smaller than non-infected ones. The same trend has been found in Myotis blythii species, but interestingly this
effect was not present in M. schreibersii. The high prevalence of parasites on M. schreibersii, coupled with the lack
of effect on body size suggests the development of a high parasite tolerance.
Phylogenetic origins of the avian MHC Class IIB
Julien Goebel, [email protected], University of Lausanne
Gene duplication is thought to be one of the primary sources of adaptive evolution. The major histocompatibility
complex (MHC) multigene family is a well-known example of an important ecological novelty coming from
duplication events. It encodes genes involved in the vertebrates’ adaptive immune response and stands for the
most polymorphic genetic system known to date in vertebrates. Its frequent gene duplications and losses result in a
marked variation in gene number and genomic organization between vertebrates. Mammalian MHC Class II ß chain
(MHCIIB) paralogs evolve independently and their duplication history can be traced back over tens of millions of
years. Recent studies on birds report also strong evidence for the persistence of two ancient MHCIIB lineages
(DAB1 & DAB2) over at least 100 million years, unequally distributed between bird species. We isolated and
recovered MHCIIB genes from species all over the avian phylogeny. We figured out mechanisms that broke the
duplication signal by reconstructing avian MHCIIB recombination and selection histories, and assessing its
concerted evolution pattern. Thus, we could identify gene regions that reflect the history of the duplication. We
reconstructed the phylogenetic history of avian MHCIIB and provided an accurate estimate for the origin of the two
ancestral lineages.
66
Interactive effects between root herbivores, natural enemies and climatic variation on maize yield
Anouk Guyer, [email protected], Universität Bern; Matthias Erb, [email protected], Universität
Bern; Christelle Robert, [email protected], Universität Bern
Climatic variation influences the performance of organisms and their interaction with each other. Prediction
models of crop plants mostly include abiotic factors, but neglect the effect of damaging pests and diseases, which
themselves depend on environmental variation. Diabrotica virgifera is one of the major pests in maize production
but can be controlled with the entomopathogenic nematode Heterorhabditis bacteriophora, which is already
widely used as biological control agent against other pest herbivores. Summer precipitation in Switzerland is
expected to be decreased in the future and therefore soil moisture may be an important environmental driver,
altering the performance and interaction between the three organisms. The assessment of the effect of different
soil humidity levels reveals mechanistic insight into the tritrophic system, including direct effects of D. virgifera on
plant growth and physiological parameters, as well as indirect effects of entomopathogenic nematodes, which
control the root-herbivores attack and therefore influence the crop plants susceptibility. Furthermore, data are
completed with the analysis of the impact of soil moisture on the composition of plant secondary metabolites,
including defensive compounds against D. virgifera.
The Impact of Intraspecific Diversity on Stability in Chlamydomonas rheinhardtii
Matthias Hertl, [email protected], eawag & ETH; Anita Narwani, [email protected], eawag
Interspecific genetic diversity is an important factor for the stability of communities when confronted with
environmental variability and the threat of species invasions. However, not much research has been done into the
effects of intraspecific diversity on population stability, an area of inquiry particularly relevant to the field of algal
biofuels. We assessed the effect of intraspecific diversity using 3 lineages of the green microalgae Chlamydomonas
rheinhardtii commonly used in biofuels research in outdoor raceway ponds. Analysis of chlorophyll-a fluorescence
and cell counts showed that a population with a genetically diverse background tends to be more stable than those
comprised of monoclonal strains for certain measures.
67
Belowground community responses to grassland management intensification in mountain
meadowland
Chantal Herzog, [email protected], University of Bern; Jean-Yves Humbert, [email protected], University of Bern; Malie Lessard-Therrien, [email protected], University of
Bern; Marcel van der Heijden, [email protected], Agroscope Reckenholz-Tänikon;
Raphaël Arlettaz, [email protected], University of Bern
Nowadays, montane and subalpine European grasslands are confronted to different pressures due to changes in
agricultural practices. The application of liquid manure instead of solid manure and the progressive replacement of
traditional ground irrigation by aerial irrigation with sprinklers are two examples of novel and common used
practices. Their effects on plant and numerous animal communities have already been studied. However, there is a
lack of knowledge about belowground responses. Belowground communities and particularly arbuscular
mycorrhizal fungi (AMF) play a fundamental role in ecosystem functioning and are crucial drivers of vegetation
dynamics and ecosystem services such as nutrient cycling. This study investigated the effect of liquid manure and
aerial irrigation on the abundance of AMF and litter decomposition within a long-term project with the objective to
find the best trade-off between biodiversity conservation and hay production. Six intensity levels of irrigation and
fertilization were experimentally manipulated in eleven meadows across the Swiss Alps. We collected soil samples
and performed a trap culture experiment to assess AMF abundance. For litter decomposition, a novel tea bag
approach was followed (see Keuskamp et al. 2013, Methods Ecol. Evol.). Decomposition measured with tea bags
burials was higher under maximal intensity levels compared to minimal intensity management. This result suggests
that this ecosystem process is accelerated by agricultural management intensification. Investigation of AMF
colonization is still ongoing, but results should be available for Biology16. Our outputs shed light on belowgroundaboveground interactions. The ultimate goal is to provide management recommendations to farmers that would
allow decent yield while preserving functional diversity.
Multiplex amplicon sequencing for genotyping and phylogenetic inference in polyploid wild wheats
Stella Huynh, [email protected], University of Neuchâtel; François Felber, [email protected], University
of Neuchâtel, Musée et jardins botaniques cantonaux de Lausanne; Christian Parisod, [email protected],
University of Neuchâtel, UMR-Le-Moulon
Inferring the evolutionary history of polyploid species remains a major challenge. Recent theoretical advances have
dramatically improved inference of reticulation and incomplete lineage sorting from genome-wide data. However,
obtaining good quality data from complex polyploid genome remains a bottleneck. Capturing polymorphisms
within and among homeologous genes is indeed crucial for such phylogenetic work. Here, we report on a
multilocus dataset of 48 single-copy loci in hundreds of individuals from four diploid and four polyploid wild wheat
species (Aegilops spp.). Loci of 400bp, encompassing polymorphic introns, are PCR amplified and individually
tagged for multiplex sequencing of overlapping paired-end reads with Illumina MiSeq. After cleaning and
demultiplexing, reads are aligned for each individual and locus, and spurious SNPs are filtered out based on their
frequency. From diagnostic SNPs, haplotypes are then extracted and their frequencies evaluated within individuals.
Homeologs are clearly distinguishable within polyploids for most loci and easily assignable to putative diploid
progenitors. Inferred haplotype frequencies are also consistent with dosage expectations according to ploidy level
of the individual and revealed a low nucleotide variation within homologs, as expected for predominant selfing
species. A data resampling in a subset of individuals, sequenced at a high coverage, allows us to assess the minimal
coverage required for recovering all haplotypes. At 50X, main haplotypes are still inferred and their frequencies
stably estimated. This method thus offers high-quality data for genotyping multiple alleles and lays foundations for
accurate phylogenetic inferences in complex polyploid systems.
68
Assembly of Amphioxus genome
Kamil Jaron, [email protected], Department of Ecology and Evolution, University of Lausanne; Marc RobinsonRechavi, [email protected], Department of Ecology and Evolution, University of Lausanne
Amphioxus are ancient taxon of fish-like marine organisms particularly interesting for studies of the evolution of
chordates, since the taxon represents one of three taxa diverged from a common chordate ancestor about 520
million years ago. Comparison of amphioxus genome to vertebrates has been instrumental in learning about the
common ancestor of chordates and the whole genome duplications which likely occured at the origin of
vertebrates. The Florida amphioxus (Branchiostoma floridae) genome has already been sequenced using Illumina
pair-end whole genome shotgun strategy. Most of the protein coding genes (more than 95%) were captured, but
the complexity of the genome and an extensive allelic variation (3.7% of SNPs; 6.8% polymorphic insertions or
deletions) led to an assembly consisting 62 scaffolds longer than 2.6Mb and many smaller ones and therefore many
aspects of the genome remain unknown. Here we present a de novo assembly of a Mediterranean amphioxus
Branchiostoma lanceolatum based purely on 83 SMRT cells of PacBio RS II system (9.7M of reads of total length
80Gbp). This study both brings insights to evolutionary biology and demonstrates capabilities of long read
sequencing for comparative genomics.
Inter- vs intra-individual variation and temporal repeatability of escape responses in the coral reef fish
Amblyglyphidodon curacao
Maïwenn Jornod, [email protected], University of Neuchâtel; Dominique G. Roche,
[email protected], University of Neuchâtel
Fast-start escape responses are critical behaviours used by fishes during predator-prey encounters and some
interactions with heteroand conspecifics. In experimental studies, escape responses are often measured once per
individual and considered representative of maximum performance. However, few studies have compared
variability and repeatability in escape performances within and among individuals. Using the tropical damselfish
Amblyglyphidodon curacao, we quantified inter- and intra-individual variation in behavioural and kinematic
components of escape performance during repeated presentations of a stimulus at 15 min intervals. Individual
maximum escape performance was repeatable through time, but there was considerable variation in the
magnitude of responses both among and within fish. We found no evidence of habituation or fatigue due to
repeated stimulations, suggesting that fish can be stimulated multiple times to ensure that an accurate estimate of
maximum escape performance is obtained.
69
Symbiont-conferred resistance compromises aphid control by parasitoids
Heidi Kaech, [email protected], ETH & eawag; Christoph Vorburger, [email protected], ETH &
eawag
From a biocontrol perspective, the use of all-female parasitoids is desirable, because only females kill hosts. On the
other hand, asexual parasitoids may fail to track evolutionary changes in the pest insect population. To compare
biocontrol efficiency of asexual and sexual populations of the parasitoid wasp Lysiphlebus fabarum, population
cages were set up with broad beans (Vicia faba) infested by large aphid populations (Aphis fabae) of high or low
clonal diversity. Upon exposure to asexual or sexual parasitoids, population development was monitored during 13
weeks. Parasitoids went extinct in 12 out of 20 cages, and only 5 of the remaining 8 cages still contained significant
numbers of parasitoids at the end of the experiment. Although there was some indication that asexual parasitoids
might have a stronger effect on aphid population growth, biocontrol ultimately failed regardless of the parasitoid’s
reproductive mode. The reason was rapid selection for resistant aphids infected with the secondary bacterial
endosymbiont Hamiltonella defensa. Thus, we had to reject our hypothesis that sexual parasitoids might be
superior biocontrol agents when pest populations change, because even the sexual parasitoids did not adapt fast
enough to the rapid evolution of symbiont-conferred resistance in the aphids. Given that a substantial proportion
of pest aphids in the field harbour H. defensa, this work points to the need for careful exploration of
predispositions towards resistance against parasitoids in integrated pest management.
The paradox of MHC susceptibility alleles
Joshka Kaufmann, [email protected], unil; Tobias L. Lenz, [email protected], MPI, Plön; Manfred
Milinski, [email protected], MPI, Plön; Christophe Eizaguirre, [email protected], QMIL, London
Host-parasite interactions are one of the major mechanisms explaining the maintenance of high allelic diversity at
the Major Histocompatibility Complex (MHC). Indeed, under negative frequency-dependent selection, alleles
conferring resistance are being favored against common pathogens and thus increase in frequency in the next
generation. Surprisingly, MHC alleles associated with host susceptibility to pathogens can occur almost as
frequently as MHC alleles linked to resistance. Several hypotheses have been proposed to explain this paradox:
First, MHC susceptibility alleles could have contrasting effects on different parasite species (i.e. resistance to one
and susceptibility to another species). Second, a resistance allele against one species could alter within-host
interspecific parasite competition and indirectly favor a competing parasite species. We tested these hypotheses by
investigating whether susceptibility alleles could be detected under exposure to one or two nematode parasite
species in lab-bred three-spined stickleback families. A specific MHC Class II haplotype was associated with higher
infection levels of one of the nematode parasite, but only in fish exposed singly. Our results show that infections
with a single parasite species are enough to detect alleles associated with susceptibility. We suggest that this MHC
haplotype is maintained in natural populations due to its association with resistance against other parasite species.
In an ecological context, frequent multiple infections might therefore hide mechanistic effects of MHC alleles and
should be taken into consideration when investigating evolution of immune genes under natural conditions.
70
Comparative analysis of latitudinal and elevational shift in phenology of European odonates
Rassim Khelifa, [email protected], University of Zurich
Ecologists are interested in understanding and predicting how species’ temporal niches change due to climate
warming. In most taxa, the timing of life history traits such reproduction, hibernation, and metamorphosis varies
along geographic (temperature) gradients such as latitude and elevation. These same traits are also changing in
response to recent increases in temperature. This study assessed shifts in flight season of adult odonates, and their
geographic patterns, using a 34-year dataset of atlas records collected in six Western European countries. I
analyzed both latitudinal and elevational gradients, and evaluating their association with historical trends in air
temperature. Comparison between the two kinds of gradient was based on an elevation-for-latitude model of
temperature similarity. Phenology shifted toward earlier dates along both gradients, with considerable variation
among species in response. Temperature changes were tightly correlated with the shift in phenology. However, the
response differed between gradients: phenological change was higher in the most northern latitudes but lower in
the upper-most elevations. The contrasting trends across latitude and elevation may result from differences in
historical patterns of temperature in the two gradients.
Keywords: Climate warming, phenological shift, latitude, elevation, odonates
A Matter of Grass – Multi-Species Responses to Diversity Alteration
Clemens Kleinspehn, [email protected], IPS, University of Bern; Markus Fischer,
[email protected], IPS, University of Bern
Diversity has been reported to positively influence the productivity of a plant community. Earlier studies indicate
that the overall production stability of a community increases, although the species specific stability decreases with
increasing diversity. However, productivity is often only quantified by total biomass. In this study we are going on
step further and highlight a more detailed picture on productivity responses related to species richness and
functional diversity. In 2015 we collected aboveground biomass of 20 plant species in a 5-years old grassland
experiment with designed levels of species richness. Additionally the experimental design covers two gradients of
functional trait diversity. One gradient includes traits which are related to spatial resource acquisition, the other
includes traits in relation to temporal resource acquisition. The collected biomass has been split after species
identity and plant shoot density has been quantified. Our results show that total shoot density increases, but
species specific shoot density decreases with species richness. Functional trait diversity has an interactional effect
on the species richness effect by shifting it in a slightly more positive direction. More detailed analysis suggests that
described effects are stronger pronounced in grass species, and plant species which differ in functional traits in
relation to spatial resource acquisition. How these results are related to collected biomass and overall productivity
will be investigated in further analysis.
71
Conflicting Selection by Pollinators and Herbivores
Anina Knauer, [email protected], University of Zurich; Florian Schiestl, [email protected],
University of Zurich
To find host plants, herbivores are believed to often eavesdrop on floral signals evolved to attract pollinators. This
can cause a trade off in plants between the attraction of mutualists and the avoidance of antagonists leading to
conflicting selection on floral signals. Bumble bees (Bombus terrestris) and cabbage butterflies (Pieris brassicae) are
both efficient pollinators of Brassica rapa, but cabbage butterflies also use B. rapa as a host plant for their offspring.
Their caterpillars mainly feed on flowers and have a strong negative effect on plant fitness. In a cage experiment we
exposed Brassica rapa plants to a) bumble bees only, b) cabbage butterflies only and c) bumble bees and cabbage
butterflies. We found a preference for the scent compound phenylacetaldehyde and corolla size in bumble bees
and cabbage butterflies when visiting flowers. Additionally, butterflies were attracted to plants by the same two
floral signals for oviposition. This led to a positive selection on these floral signals when plants were exposed to
bumble bees only, but to the absence of selection when plants were exposed to both insect species or cabbage
butterflies only. This is the first study demonstrating that herbivores have very similar preferences for floral signals
as pollinators. This causes a conflict in the plant between the attraction of mutualists and the avoidance of
antagonists.
Heritability of fitness under different environmental conditions
Eva Koch, [email protected], University of Zurich; Frédéric Guillaume, [email protected], University
of Zurich
Evolution occurs when selection acts on a trait that has a heritable basis, meaning that a significant proportion of
the observed phenotypic variance in a population is explained by genetic variance. Furthermore, the trait must be
genetically correlated with fitness to evolve under natural selection. That implies that there must be genetic
variance in fitness. Genetic variance in fitness is therefore a prerequisite for evolution and can give an estimate of
the current adaptive potential of a population. Heritability, the proportion of the genetic variance, is not constant
but influenced by the environment. Consequently, the evolutionary potential for adaptation might be different
dependent on the environmental condition. Tribolium castaneum (red flour beetles) were used to investigate the
influence of the environment on heritability and different variance components of fitness. Fitness of females
(offspring number) was measured under four conditions, a control condition and three stress treatments in which
we increased temperature or decreased humidity. A full sib/ half sib breeding design was applied to estimate the
genetic variance of fitness. Further, we tested for genotype by environment interactions (GxE). We found that
offspring number was significantly affected by the treatments. The highest offspring number was found under
control conditions and the lowest under the most stressful treatment (high temperature plus low humidity).
Heritability was similar in all treatments but the evolutionary potential estimated with coefficients of the additive
genetic variance was much higher under stressful conditions compared to the control. Interestingly, we found a
significant effect of the mating partner of females on offspring number, which was most pronounced in the most
stressful treatment. Additionally, there was evidence for GxE interactions between offspring number in hot and dry
conditions, showing that the effect of a treatment depends on the genotype.
72
Widespread signatures of selection at secreted peptidases in a fungal plant pathogen
Parvathy Krishnan, [email protected], ETH, Zurich; Bruce A. McDonald ,
[email protected], ETH, Zurich; Patrick Christoph Brunner, [email protected], ETH, Zurich
Secreted peptidases have been extensively studied for their role as virulence factors. Pathogens may deliver
peptidases into their host cells to derive nutrients or to modify protein components of the host defense machinery
and ultimately suppress defense responses. In this study we combined transcriptomics, comparative genomics and
evolutionary analysis to investigate the significance of 39 secreted peptidases in the fungal wheat pathogen
Zymoseptoria tritici and its close relatives on wild grasses Z. pseudotritici and Z. ardabiliae. RNA-seq data revealed
that a majority of the secreted peptidases displayed differential transcription during the course of Z. tritici
infection, indicative of life cycle specialization. Genetic analyses detected widespread evidence of diversifying
selection acting on most of the secreted peptidases. The aspartic endopeptidases emerged as a particularly
interesting group, suggesting a key role in host pathogen co-evolution, host adaptation and pathogenicity. For
example, aspartic endopeptidases showed lineage specific rates of molecular evolution, suggesting altered
selection pressure in Z. tritici after host-specialization on domesticated wheat. Furthermore, sister genes of aspartic
peptidases evolve at different rates, possibly as a result of sub-, or neo-functionalization after gene duplications.
This detailed study of secreted peptidases in Zymoseptoria tritici is a further step in determining suitable targets for
controlling this important plant pathogen.
Unprecedented rate of sex-chromosome turnover in ranid frogs
Guillaume Lavanchy, [email protected], University of Lausanne; Alan Brelsford, [email protected],
University of Lausanne, University of California, Riverside; Daniel Lee Jeffries, DanielLee.Jeffries.ch, University of
Lausanne; Wen-Juan Ma, [email protected], University of Lausanne; Nicolas Perrin, [email protected],
University of Lausanne
Initial studies on a few model species with strongly heteromorphic (differentiated) sex chromosomes have led to
the view that sex chromosomes necessarily decay, due to the suppression of recombination. However, the sex
chromosomes of many vertebrates are homomorphic (morphologically similar). Two mechanisms that can counter
the decay have been proposed. The first is occasional X-Y recombination, which can prevent the accumulation of
deleterious mutations on the Y. The second is sex-chromosome turnover, whereby an autosome takes over the role
of sex determination, thus resetting the decay. True frogs (Ranidae) have been suggested to present a high rate of
turnover, with a subset of the 13 chromosomes being recurrently recruited for sex. The first step in studying the
dynamics of turnovers is to document which chromosome determines sex in a large number of species. Using
Restriction-Associated DNA Sequencing (RADseq) on over 700 individuals from 16 species, we looked for sexspecific markers and mapped them to the well-assembled genome of the clawed frog (Xenopus tropicalis) for
unambiguous identification of the chromosomes. We complemented our results with data from the literature,
providing us with information for about 30 species or populations. Reconstructing the phylogeny of the studied
species allowed us to infer the ancestral states and count the number of transitions. We found that the rate of
turnover in this family is indeed extremely high, with almost each species having its own sex chromosome. We also
uncovered novel cases of within-species polymorphism of sex determination. Our RADseq data allowed us to
estimate the size of the differentiated part of the genome, providing insights on the rate of differentiation in these
amphibians.
73
Elevation and daily temperature range independently affect tick occurrence and abundance
Mélissa Lemoine, [email protected], University of Zurich; Barbara Tschirren ,
[email protected], University of Zurich
Drastic changes in the distribution of the sheep tick Ixodes ricinus, a vector for various vector-borne diseases, were
observed during the past decades. A large number of biotic and abiotic factors are invoked to explain these
changes, however their relative importance and interactions are generally not well quantified. Here, we examined
the influence of soil and air temperature on the abundance and occurrence of Ixodes ricinus across different
elevations in the Swiss Alps at the limit of its range. Because the three developmental stages (larvae, nymphs and
adults) may cope differently with abiotic factors, we investigated variation in the relationship between abundance
and environmental variables across developmental stages. We found that temperature and elevation
independently affected the occurrence and local abundance of ticks. The occurrence of larvae decreased linearly
with elevation, while the rate of decrease accelerated with increasing elevation in nymphs and adults. Soil
temperature explained a part of the variance attributed to elevation, but could not explain the accelerated
decrease at the nymph and adult stage. In contrast, the relationship between elevation and local abundance was
similar for all tick stages. Soil temperature did not significantly explain the variation in tick abundance attributed to
elevation. Across the different elevations, we found that tick abundance decreased with increasing daily range of
air temperature. To our knowledge, this is the first study that examined the impact of abiotic factors on tick
occurrence and local abundance simultaneously. This approach can contribute to a better understanding of the
interlinked factors that affect the distribution and spread of a common vector of wildlife and human disease.
The effect of warming and non-prey diversity on trophic interactions
Leah Lewington-Pearce, [email protected], Queen Mary University of London
Our climate is warming and global temperatures are projected to rise by around 3oC at the end of this century.
Warming can alter the structure and dynamics of ecological communities and therefore a deeper understanding of
its consequences is a key to improve our predictions of future ecosystem states. It has been shown that
heterotrophs (consumers) are more sensitive to warming than autotrophs (resource), due to increased metabolic
and feeding rates. Consequently, warming can destabilize food webs by strengthening trophic interactions. On the
other hand, high species richness is known to enhance stability in some systems, potentially mitigating the negative
effect of climate warming. More diverse systems encompass a higher ratio of inedible (non-prey) to edible (prey)
species for a focal predator. Previous work has suggested that both density and diversity of non-prey species may
reduce the strength of trophic interactions by reducing predators’ foraging efficiency and stabilizing predator-prey
dynamics that would otherwise be unstable. My research aims to determine the interactive effect of climate
warming and non-prey species diversity on food web stability and resilience to perturbation, using a zooplankton
(Dapnia pulex)-phytoplankton (Chlorella vulgaris) predator-prey model. I will be manipulating non-prey diversity
based on phytoplankton size factorially with 3 temperature treatments, measuring the response of cell density, cell
size, pH and CO2 flux. I aim to determine the ecological mechanisms that allow ecosystems to resist the pervasive
changes in temperature and identify which ecosystems are more sensitive to climate warming. This will allow
critical implication of more effective ecosystem management.
74
Environmental drivers and biological control of invasive ragweed populations across Europe
Suzanne Lommen, [email protected], University of Fribourg; Caspar Hallmann, [email protected],
Radboud University Nijmegen; Eelke Jongejans, [email protected], Radboud University Nijmegen; Benno
Augustinus, [email protected], CABI Switzerland/University of Fribourg; Urs Schaffner, [email protected],
CABI Switzerland; Heinz Müller-Schärer, [email protected], University of Fribourg
The continued spread of the allergenic common ragweed, Ambrosia artemisiifolia, in Europe, is a growing medical
and agricultural problem. Within the European Research network SMARTER “Sustainable Management of Ambrosia
artemisiifolia in Europe” we take a demographic approach to address this problem, examining i) which
environmental factors drive the population dynamics of ragweed, and ii) how potential biological control agents
would affect long-term dynamics.
The quantification of ragweed population dynamics is complex, because it is a highly plastic annual plant, whose
seeds can persist for tens of years in the soil seed bank, while recruitment is highly dependent on soil disturbance.
To understand how the environment affects spatial and temporal variation in local dynamics, we collect data on
tens of natural, unmanaged populations across the European continent and the Black Sea region over multiple
years. We use these to construct size- and density-dependent demographic models.
In parallel, we perform experimental work under controlled conditions to assess how potential biological control
agents affect these dynamics. We specifically elaborate the reciprocal density-dependent interactions between
ragweed population dynamics and that of the ragweed leaf beetle, Ophraella communa. Integration into
demographic and spatial models will allow projections about the efficacy of biocontrol agents, and plant
distributions respectively, across a range of environmental conditions.
Testing the limits of three Bromeliaceae species in Neotropical Mountains
Talita M. Machado, [email protected], Federal University of Minas Gerais(UFMG-Brazil) & unil;
Leonardo M. Versieux, [email protected], Federal University of Rio Grande do Norte(UFRN-Brazil); João
Renato Stehmann, [email protected], Federal University of Minas Gerais (UFMG-Brazil); Nicolas Salamin,
[email protected], Université de Lausanne
Bromeliaceae is a family of plants with exclusive geographical distribution in the Neotropics. The species in this
family have remarkable ecological importance in many communities, providing shelter and feeding resources for
fauna and other associated flora. Therefore, communities where bromeliads are widespread usually carry a large
biodiversity. Southeastern Brazil holds three main mountain ranges (Sierra do mar, Espinhaço, and Mantiqueira)
considered as centers of diversity for Bromeliaceae. All three mountains belong to the Atlantic Forest biome,
considered a endemic but highly threatened biodiversity hotspot. The heterogeneous topography of this biome
facilitates the isolation of plant populations and can lead to speciation. However, the extent of morphological and
genetic differentiation between species remains unclear. This morphological overlap may hinder the delimitation of
species, which are the basic unit of study in several fields in biology.
In this work we investigated the boundaries between three species of Tillandsioideae subfamily (Bromeliaceae).
Vriesea crassa, V. hoehneana and V. itatiaiae have limited geographic distributions above 1.700 m in the Atlantic
forest with sympatric areas. Morphological differences between species are scarce leading to misidentification,
taxonomic issues, and difficulties understanding the processes of species diversification in the region. Here, we
evaluated the genetic diversity between populations of the three species, and their relationship with biogeographic
patterns. We conducted a phylogeographic analysis sampling 180 individuals from nine populations, and multiple
molecular markers (plastid regions Psba-trnH and matK). Our results will provide evidence of the processes
governing the geographic distribution of these lineages, allowing for inferences about the amount of genetic
divergence, population isolation, and species delimitation. Altogether these results are important elements in the
understanding of the diversity generation in threatened environments.
75
The mossy north: an inverse latitudinal diversity gradient in bryophytes
Rubén G. Mateo, [email protected], Department of Ecology and Evolution, University of Lausanne,
Biophore, 1015 Lausanne, Switzerland; Olivier Broennimann, [email protected], Department of Ecology
and Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland; Signe Normand,
[email protected], Section for Ecoinformatics & Biodiversity, Department of Bioscience, Aarhus
University, Ny Munkegade 114, 8000 Aarhus C, Denmark; Blaise Petitpierre, [email protected], Department
of Ecology and Evolution, University of Lausanne
It remains hotly debated whether latitudinal diversity gradients are common across taxonomic groups and whether
a single underlying mechanism can explain such gradients. We compared species richness gradients between
vascular plants and bryophytes in Europe to determine whether species richness increases with decreasing latitude,
as predicted by theory, and whether the assembly mechanisms differ between these two taxonomic groups.
Vascular plants and bryophytes exhibited marked but opposite latitudinal species richness gradients in Europe.
Species richness increased towards the south in vascular plants but towards the north in bryophytes. Whereas
vascular plant species distributions were highly nested in the north and displayed high turnover in the south,
indicating species exclusion towards the north and increased opportunities for speciation in the south, the betadiversity patterns of bryophytes did not vary with latitude. This suggests different assembly mechanisms between
the two groups and defines the ‘mossy north’ as a hotspot of bryophytes diversity.
Duration of the post-fledgling dependence period in Barn Owls
Carolina Massa, [email protected], University of Lausanne; Bettina Almasi, [email protected],
Swiss Ornithological Institute; Alexander Roulin, [email protected], University of Lausanne
In birds, the post-fledging dependence period (the period from the first flight to dispersal) represents a critical
stage in the life cycle. When and how far individuals move might be crucial for their survival and future
reproductive success. Birds of prey show considerable variation in the length of the dependence period and also in
some of the factors that determines its end. In the barn owl (Tyto alba) we have the unique situation that we can
link differences in melanic plumage coloration to different physiological and behavioural traits (e.g. ability to cope
with stress, dispersal, survival). In the present study we investigated the age at independence from the nest site in
95 barn owl fledlgings with different rearing conditions. Half of the individuals received an implant of the stresshormone corticosterone which increased the stress-hormone level to a moderate range for two to three days
during the nestling period and the other half received a placebo-implant as control. Birds were equipped with radio
transmitters and they were relocated at their diurnal roost sites periodically until the end of the year.
The general pattern that described the movements in the studied period was a sigmoid curve, consistent with
previous studies. With generalized additive mixed models (GAMMs) with the distance to the nest as the response
variable, we explored the effects of our treatment jointly with a set of variables that included sex, colour traits of
the individuals, age, and hatching date. We conducted first-passage time analysis to evaluate the age at the first
dispersal period, and a series of comparison with simulated trajectories to assess whether their movement
pathway was random, more dispersed than random, or more constrained than random pathways.
76
Multilevel selection in aphids' defensive symbiosis: conflicts between selection levels and adaptations
preventing them
Hugo Mathé-Hubert, [email protected], eawag - ETH; Heidi Kaech, [email protected], eawag - ETH; Christoph
Vorburger, [email protected], eawag – ETH
Since they appeared, no macro-organisms have been living free of bacteria. Adaptations to these hosted bacteria
are thus probably as old as the origin of multicellularity. In particular, I am focusing on physiological adaptations
that might allow the host to control the evolution its mutualistic endosymbiotic bacteria when they are vertically
transmitted from parent to offspring.
When symbionts are vertically transmitted, mutualism is expected to be favoured by the selection acting on the
hosts/symbiont couples because the strain of bacterial symbionts associated with the host affects its fitness and
thus behave as a host gene. This correspond to a ""between host selection level"" that favour mutualisms.
However, endosymbiotic bacteria undergo many cycles of reproduction during the host’s life and several
endosymbiont strains might co-occur within a same individual host – e.g. because of mutations or horizontal
transmission. In these condition, a particular bacterial strain could be favoured by selection acting within the host
during the host life.
While the previous between host selection, acting at each host generation, selects for bacteria improving the host’s
fitness, this selection acting within the host favours bacteria which grow the fastest. This faster growth rate can be
achieved by increased consumption of host resources, which might ultimately lead to the development of a selfish
bacterial strain.
This problem can be compared to the development of “selfish cell lineages” such as cancer cells. Starting from what
is known about protection against selfish cells, I will present mechanisms that could allow the host to prevent or
control within-host evolution of symbionts to prevent evolution of symbiotic selfishness.
Snowbeds are more affected than other subalpine-alpine plant communities by climate change in the
Swiss Alps
Magalì Matteodo, [email protected], University of Lausanne - IDYST; Pascal Vittoz, [email protected],
University of Lausanne – IDYST
Mountain regions are warming rapidly and the upward shift of plant species has been observed on many alpine and
nival summits. On the other hand, the reaction of the subalpine and lower alpine plant communities to the current
climate changes has been little investigated so far. The increasing temperatures, combined with lower
precipitations, lead to an earlier snowmelt and therefore longer growing seasons.
In this study 63 old, exhaustive plant inventories have been selected in the Swiss Alps and revisited after 25 to 50
years later. The records cover a broad range of plant communities distributed along a subalpine–alpine elevation
gradient. Both calcareous and siliceous grasslands have been studied, as well as snow bed and ridge communities.
The alpha-diversity increased in every plant community, likely because of the arrival of new species, but differences
in sampling cannot be excluded. As already observed on mountain summits, new species were not very diversified,
and this led to a homogenization of the plant records within a community. The studied alpine grasslands were quite
stable in terms of species composition, whatever the bedrock type, although some of the species increasing in
frequency indicate a trend towards warmer conditions. In contrast, snow bed communities showed pronounced
vegetation changes and a clear shift towards composition of dryer grasslands. The longer growing seasons allow
alpine grassland species, taller and hence more competitive, to colonize the snowbeds. This research showed that
subalpine-alpine plant communities reacted differently to the on-going global changes. Plant communities linked to
long snow cover are the most vulnerable to climate change and their persistence in the near future is seriously
threatened.
77
Population genetics of lions and leopards in the Kalahari, Botswana
Jelena Mausbach, [email protected], Department of Evolutionary Biology and Environmental Studies,
University Zurich and Leopard Ecology & Conservation; Fabian Haas, [email protected], Department of
Evolutionary Biology and Environmental Studies, University Zurich; Lukas Keller, [email protected],
Department of Evolutionary Biology and Environmental Studies, University Zurich; Barbara König,
[email protected], Department of Evolutionary Biology and Environmental Studies, University Zurich
Habitat destruction and fragmentation due to human development or change in land use can lead to isolation of
populations. Such processes may result in disruption of gene flow and in reduction of a local population’s genetic
variability. Large carnivores are especially vulnerable to those effects due to their relatively low fecundity, slow life
cycle and need for relatively large home ranges. In Botswana, the land outside of large unfenced wildlife reserves is
typically used as farmland. We address the question whether and how large predators cope with such an
anthropogenic environment. We do so by investigating genetic diversity, population size and demographic
structure of different populations of carnivores. We will use such information to analyse the consequences of
conservation actions such as translocations for maintaining genetic variability.
We assess gene flow in two carnivore species: the African leopard (Panthera pardus pardus), a cryptic, solitary
predator that inhabits wildlife reserves and farmland. Leopard populations therefore should be less affected by
disruption in gene flow than those of the African lion (Panthera leo), a rather conspicuous, social predator. Lions
nowadays mainly survive in large wildlife reserves, which might result in a more distinctive genetic population
structure.
Since 2002 we randomly collected skin and blood samples of leopards and lions living in low density populations in
the Khutse Game Reserve and Central Kalahari Game Reserve, Botswana (total size: 55 000 km2). We
complemented the data set with skin samples from shot animals, collected with the assistance of the Botswanan
Department of Wildlife and National Parks. Standard population genetic analyses such as FIS and allelic richness
were assessed using microsatellite analyses of 40 primers for lions (n = 109) and 30 primers for leopards (n = 128);
(primers originated from domestic cat, Felis catus). We will present the genetic population structure of those
Kalahari carnivores with the aim to extend this analysis to entire Botswana.
78
The differing responses of hoverfly guilds to mowing regimes
Sandro Meyer, [email protected], University of Bern; Debora Unternährer,
[email protected], University of Bern; Jean-Yves Humbert, [email protected],
University of Bern; Raphaël Arlettaz, [email protected], University of Bern; Myles Menz,
[email protected], University of Bern
We investigated if alteration to traditional mowing regimes in the Swiss lowlands would have a positive impact on
hoverfly community composition as a whole and in more detail on the main hoverfly larval feeding guilds. A
randomized block design was applied with 12 replicates of each of the following mowing regimes: Control (Cmeadows): first cut not before 15June (the conventional Swiss AES management of extensive meadows); Refuge (Rmeadows): first cut not before 15 June, but leaving 15% of the meadow uncut as a refuge; and Delayed (Dmeadows): delaying cutting for a month to 15 July. Hoverflies were collected by pan trapping and sweep netting at
each meadow, once before the first cut (15 June) and once after the first cut, but before 15 July. The sampling
method greatly influenced the hoverfly community that was caught. Pan traps exhibited higher species richness in
July in C-and D-meadows than R-meadows, due to a potential bias of attracting high abundance of saprophagous
species. In contrast, sweep netting resulted in a higher abundance and species richness in D-and R-meadows
compared to C-meadows, due to the abundance of small aphidophagous species that occurred in the unmown Dmeadows in July. The potential bias of pan traps attracting hoverflies from the surrounding in C-meadows in July
when mown indicates the importance of using the correct sampling method when vegetation conditions
(management) differ between sampling sites. Overall, D-meadows exhibited a higher abundance than R-and Cmeadows and species richness than R-meadows, indicating that delayed management could have a positive impact
on hoverfly communities in lowland grasslands. However, the different responses of feeding guilds and other
pollinator groups (ex. wild bees and butterflies) to the mowing regimes, highlights the fact that one management
option might not be suitable for the overall community. Therefore, it is necessary to create a mosaic of meadows
with refuges and others with delayed mowing regimes to provide both vital nesting and foraging habitats for a
diversity of species.
The effects of temperature and dispersal on species richness in microbial metacommunities
Elodie Parain, [email protected], University of Fribourg; Sarah Gray, [email protected], University of
Fribourg; Louis-Félix Bersier, [email protected], University of Fribourg
Dispersal plays an important role in maintaining biodiversity at local and regional scales in metacommunities, but
little is known about the combined effects of temperature changes and dispersal on biodiversity. The theory
predicts that biodiversity is maximized at intermediate dispersal rates and that this relationship is flattened when
competition increases. As temperature is expected to increase competition, the diversity-dispersal relationship is
expected to flatten with temperature increase. It is interesting to also test this theory with communities from
different successional stages as their organization and dynamics are different. We explore this question using
aquatic communities of Sarracenia purpurea from two successional stages: early (2 weeks old) and late (4 weeks
old). We grew the communities for 7 weeks in incubators and manipulated temperatures and dispersal rates. We
observed the hump-shaped relationship in communities from late succession, and there was no indication that
temperature increase flattened the relationship. Temperature increase had an effect only on the intercept,
decreasing diversity globally. In communities from early succession, the diversity-dispersal relationship was linearly
positive, and these communities were not affected by temperature. Our study shows that early- and latesuccessional communities respond very differently to both dispersal and temperature. In early communities,
temperature may have little additive effect on competition, and experimental dispersal rate may be too low to
observe the hump-shape. For late communities, the absence of flattening together with the observed decrease in
species richness may be simply due to higher mortality, a feature not included in the theory underlying our
predictions.
79
Integrating Global Change drivers and Biodiversity
Maria Alejandra Parreno, [email protected], University of Zurich; Norman Backhaus,
[email protected], University of Zurich; Michael Schaepman, [email protected],
University of Zurich; Bernhard Schmid, [email protected], University of Zurich
Global change is a term that refers to the group of processes from natural and anthropogenic origins that affect the
Earth´s environmental system and possibly its capacity to sustain life. These processes also affect biodiversity,
which in turn could translate as an impact on ecosystems services and functions. Furthermore, human features
such as freedom and security play an important role in shaping the way we affect the Earth. Some of the feedbacks
and scaling effects within these components have been studied separately and as part of meta-analysis. However,
no synthesis has been done so far in a global scale taking all features into account. Such a holistic analysis has
complexities on its own that are enhanced by a further issue, which is to assess the political, economic and cultural
features that may constrain or pave the way to sustainability.
Understanding and predicting outcomes of individual global change drivers and their interaction with biodiversity
can be addressed by specific projects within one discipline. But understanding global patterns across scales and
gradients requires interdisciplinary efforts. The aim of my research is to find patterns and establish the strength of
the different interactions within an integrative research. I will do a meta-analysis at a global scale of currently
available literature and a network analysis to understand intrinsic properties of my system, such as resilience. The
University Research Priority Program Global Change and Biodiversity gathers a diverse number of projects in
biology, ecology, geography and environmental ethics that address these issues along a latitudinal gradient and
across scales. Within this framework, I should contribute to the integration of results of the participating projects
together with external sources.
The phylogeography of the haplochomine cichlid fish Astatotilapia burtoni
Gaëlle Pauquet, [email protected], University of Basel; Daniel Berner, [email protected],
University of Basel; Walter Salzburger, [email protected], University of Basel; Bernd Egger,
[email protected], University of Basel
Lake Tanganyika (LT) belongs to the three largest lakes of Africa and lies in the East African Rift Valley, which was
continuously shaped and influenced by altering climatic conditions and tectonic processes. These processes lead to
changes in the connectivity of adjacent water bodies and lake level fluctuations, which subsequently affected the
distribution and the genetic structure of today’s aquatic fauna. Here, we are interested in the processes leading to
the contemporary distribution of the haplochromine cichlid species Astatotilapia burtoni, which occurs in LT and its
tributaries. We establish its phylogeography and reconstruct the demographic history from both a 369–bp
fragment of the mitochondrial control region and single nucleotide polymorphisms (SNPs) derived from RAD
sequencing. The datasets comprise up to 405 individuals from 32 sampling locations in the lake and contiguous
waters. The mitochondrial control region reveals relatively high genetic diversity across short geographic distances
with a deep split between eastern and western populations. From the RAD loci we aim to yield a higher resolution
of the phylogeographic relationship and draw more accurate conclusions about the true population history of A.
burtoni.
80
Disentangling the mechanisms by which global change affects ecosystem function: a multitrophic
experimental approach
Noémie Pichon, [email protected], University of Bern; Seraina Cappelli, [email protected],
University of Bern
Global environmental change threatens biodiversity and alters the functioning and stability of ecosystems. One of
the most important global change drivers is nitrogen enrichment, of natural and agricultural ecosystems. Nitrogen
enrichment in grasslands has impacts on a wide range of ecosystem functions and services through a variety of
mechanisms. It directly affects soil chemical properties and at the same time has indirect effects via loss of plant
species richness, shifts in plant functional composition (towards fast growing plant species) and changes in
multitrophic interactions. Although these effects have been studied in isolation we know very little about the
relative importance of the different mechanisms or how they might interact.
Our project aims to disentangle the effects of plant species diversity, plant functional composition, nitrogen
fertilization and foliar fungal pathogen presence on grassland ecosystem functions and services. We factorially
manipulate species diversity (1, 4, 8, 20 species), functional composition (fast & slow growing species), nitrogen
fertilization and fungal pathogens (using fungicide) in a large field experiment with 336 2m x 2m plots, established
in autumn 2015. The design will enable us to test for interactions between these four drivers, for instance between
diversity and pathogens. We will measure several variables related to temporal trends in carbon and nutrient
cycling, plant traits related to fodder production, the impact and properties of the plant pathogenic fungal
community and invasion resistance of the plant communities. Here we present the novel design of this experiment
and the planned measurements.
Recent land-use changes on managed grasslands in the Swiss Alps and their impact on plant diversity
Nestor C.E. Pöll, [email protected], University of Basel; Jürg Stöcklin, [email protected],
University of Basel
Loss of plant biodiversity in agriculturally used grassland in the Swiss Alps is mainly caused by socio-economically
motivated land use change. We determine recent changes over 12 years with a replicate study via vegetation
inventories and analyse the influence from constant and variable factors on biodiversity changes. Constant factors
include altitude, exposure, region and 3 cultural traditions of 12 villages, whereas the variable factors are land use
type (grazing, mowing, fertilization and abandonment), spatial and temporal heterogeneity. Interviews undertaken
with the land-users provide knowledge on the socio-economic conditions and land-use history of parcels. Results
confirm a major role of variable factors on biodiversity over the short time scale of 12 years. Fertilization and on
parcel level and even more surface morphology are highly correlated to species richness. Surprisingly, the least
land-use changes occurred in alpine regions, more in in intermediate, subalpine regions and the most in
mountainous valleys. Although intensification is still taking place, transitions to less-intensive land-use are
predominant and seem to have a positive influence on maintenance and re-establishment of plant biodiversity.
81
Adaptive divergence in East African cichlid fishes: a comparative approach
Jelena Rajkov, [email protected], Zoological Institute, University of Basel; Alexandra Anh-Thu Weber,
[email protected], Zoological Institute, University of Basel; Anya Theis, [email protected], Zoological
Institute, University of Basel; Walter Salzburger, [email protected], Zoological Institute, University of
Basel; Bernd Egger, [email protected], Zoological Institute, University of Basel
Species that show replicate adaptation of divergent populations along the same environmental gradient are
important model systems to address how new species are formed in natural populations. Astatotilapia burtoni is an
East African haplochromine cichlid fish that occurs in both Lake Tanganyika and affluent rivers. Our previous study
identified A. burtoni lake-stream population pairs in southern Lake Tanganyika that rest at different stages of the
‘speciation continuum’. Here we expand our ongoing study by including lake-stream population pairs from
northern Lake Tanganyika. In addition, we included another species, Haplochromis stappersi, which occurs in
sympatry with A. burtoni. We first assessed the population structure and morphological differences in both species
from northern Lake Tanganyika and compared them to the populations from the southern part of the lake. Using
microsatellite markers we detected no genetic differentiation between lake and stream populations from the
northern Lake Tanganyika. However, landmark based geometric morphometric analysis of body shape revealed the
same morphological trajectories along the lake-stream gradient as previously identified in the southern A. burtoni
populations. This indicates parallelism in adaptation, even across different cichlid species. Current work is now
investigating the molecular basis of adaptation, by performing whole genome resequencing of lake-stream
population pairs of A. burtoni and H. stappersi.
How do species interactions impact range expansions?
Martina Ramel, [email protected], University of Zurich; Florian Altermatt,
[email protected], University of Zurich; Emanuel Fronhofer, [email protected], eawag: Swiss
Federal Institute of Aquatic Science and Technology
The dynamics of species ranges are usually exclusively linked to abiotic factors, such as a species' climate envelope.
However, a potentially fundamental factor to explain the presence or absence of a species in a landscape is the
presence of other species, that is, biotic interactions like competition or predation. Since to date, most models of
range dynamics focus on abiotic factors and do not consider dispersal or species interactions we here aim at
exploring how species interactions impact range expansions by altering selection on dispersal.
An individual-based, evolutionary modeling approach is used to explore this question. The model consists of a
spatially structured population with discrete generations and logistic growth in each patch. Each individual is
characterized by a heritable dispersal rate, which can change through mutations. Discrete-time Lotka-Volterra-type
competition and Nicholson-Bailey-type predator-prey models are used to integrate facilitation, competition and
predator-prey interactions into the simulations.
The model indicates that ecological and evolutionary dynamics of range expansions can be differently influenced by
various species interactions. Positive interactions such a facilitation are expected to lead to the evolution of
increased dispersal, whereas negative interactions such as competition lead to the evolution of decreased
dispersal. For predator-prey interactions the prediction depends on the behavior of the predator. If the predator
moves and hunts its prey, predator-prey interactions are expected to select for increased dispersal. However, a
sedentary predator would lead to the evolution of lower dispersal rates. This study demonstrates that species
interactions have an important high impact on ecological and evolutionary dynamics of range expansions.
82
Integrating genetic and stable isotope analyses to infer the population structure of the Snowfinch
(Montifringilla nivalis) in Western Europe
Jaime Resano-Mayor, [email protected], University of Bern
Alpine ecosystems count among the most threatened by climate change. Species occurring in high mountains now
face high risk of habitat loss, range contractions and local extinction. The Snowfinch (Montifringilla nivalis) is a
characteristic passerine of alpine habitats in Europe. Despite its breeding nuclei are relatively well-defined, we still
know little about the species’ population structure in Western Europe. By analysing two mitochondrial genes (cyt b
and CR) and the stable isotopes of hydrogen (?2H), here we assess to which extent breeding populations of
Snowfinches in the Cantabrian Mountains, Pyrenees and Alps and a wintering population in the Eastern Pyrenees
function as a metapopulation. Most haplotypes were present in all breeding populations, but one was only found in
the Cantabrian Mountains and predominant there. The most widespread haplotypes at the breeding grounds were
found in the majority of the wintering individuals, but none of them showed the haplotype specific at the
Cantabrian Mountains. Our results suggest connectivity between all populations, although the one at the
Cantabrian Mountains seem to be more isolated. No differences in ?2H were found between breeding populations
so we could not assign the breeding grounds of wintering individuals by isotopic analysis.
Indirect reciprocity in working dogs
Nastassja Rieder, [email protected], University of Bern; Michael Taborsky,
[email protected], University of Bern
Domestic dogs are highly social animals renowned for their advanced cognitive abilities. Previous experiments have
shown that they differentiate between cooperators and non-cooperators in an iterated prisoner’s dilemma game.
Here we tested whether dogs are able to cooperate by indirect reciprocity in a situation where they can pull a rope
to provide food for a social partner which they have previously observed to interact with a stooge. Thirteen dogs of
the Swiss army were trained individually to pull food for a social partner.
In the experience phase, all dogs observed either an interaction between a cooperator or a non-cooperator with a
prospective receiver. In the test phase, the focal dogs had the opportunity to provide food either for the previous
cooperator or non-cooperator.
Our results show that as predicted, experimental subjects pulled more often for former cooperators than for
former non-cooperators. Obviously, dogs recognize the cooperation propensity of social partners by just observing
them interact, and they reward cooperators whereas they do not help non-cooperators. Apart from a similar study
in Norway rats, this is the first experimental evidence for indirect reciprocity displayed among conspecifics in nonhuman animals.
83
Structural complexity in managed and unmanaged mountain forest types: effects on habitat suitability
for indicator bird species
Stefanie Roder, [email protected], University of Bern; Veronika Braunisch,
[email protected], University of Bern & Forest Research Institute of Baden-Württemberg (FVA);
Kurt Bollmann, [email protected], Swiss Federal Research Institute WSL; Raphaël Arlettaz,
[email protected], University of Bern
The designation of natural forest reserves is a major goal of forest biodiversity conservation. However, many open
questions about the structural development in newly created forest reserves and the impact on forest species
remain. We evaluated the effect of forest management cessation in relation to habitat characteristics of four bird
species indicative of different forest structures: Capercaillie, Hazel grouse, Three-toed woodpecker and Pygmy owl.
We analyzed data on forest structure from 21 natural forest reserves in three geographic regions in Switzerland
and 18 reserves in the Black Forest, Germany. Based on a paired grid-cell setup with presence or absence of the
species sampled previously in the same biogeographic regions, we modelled habitat suitability independent of
management status and then compared habitat characteristics and suitability of forest reserves to managed forest
with species presence or absence. Additionally we correlated habitat suitability in forest reserves to the time since
designation. For Capercaillie, Hazel grouse and Three-toed woodpecker, habitat suitability in forest reserves was
significantly higher than in managed forests with species’ absence, but not different than in managed forest with
species presence. For the Pygmy owl, habitat suitability in reserves similar to that in managed forest with species
absence, and significantly lower than in managed forest where the species was present. No significant correlation
between habitat suitability and time since reserve designation was found, but there were consistently positive
trends. Similar results were found for key structural elements for each species. Forest reserves provide suitable
structures for indicator bird species, but vary greatly in structural characteristics. However this variance was neither
explained by the age of the reserve nor by the geographic region. We therefore propose to investigate further the
influence of past management practices and of other environmental factors to fully understand the consequences
of reserve creation on forest biodiversity.
Detecting the signature of local adaptation in an Alpine Brassicaceae species
Aude Rogivue, [email protected], WSL; Stefan Zoller, [email protected], GDC ETH; Rimjhim Roy
Choudhury, [email protected], UniNE; Christian Parisod, [email protected], UniNE; Felix
Gugerli, [email protected], WSL
Because fitness differences among individuals are mostly genetically determined, it is important to study the
genetic processes behind local adaptation in order to understand the responses of individuals to changing
environments. Here we investigate how much adaptive genetic variation can be found in genic and non-genic
regions of the genome. We sampled 306 individuals of the alpine rock cress Arabis alpina in different environments
in four regions of the Western Swiss Alps. We performed whole-genome re-sequencing of all individuals with an
Illumina Hiseq 2500 at an average coverage of 11x. Reads were mapped to the published reference genome for SNP
calling. Using an FST outlier test, we screened for SNPs potentially under selection to evaluate their distribution
across the genome and their presence in genic vs. non-genic regions. Transposable elements (TEs) present near
genic regions were identified in order to compare the polymorphisms of different TE families (quiescent or recently
active) and their possible role in local adaptation. Future plans include association analyses of SNPs and TEs with
various environmental factors derived from aerial photographs taken with a drone and calibrated in-situ. The
results will help us to assess the predictive power of the environmental factors driving local adaptation and to know
which genes are involved in this important evolutionary process. Quantifying the adaptive importance of different
genomic regions will help us better understand the role of TEs in local adaptation. Finally, the spatially hierarchical
sampling of individuals will allow us to study the scale of local adaptation.
84
Foraging behaviour of the Alpine swift [Tachymarptis melba] in relation to aerial insects' abundance
Christophe Sahli, [email protected], University of Lausanne
Knowledge of food abundance is precious to determine the reproductive behaviour of animals. Alpine swifts are
strictly aerial feeders spending their entire life in the air, except for the breeding period. The relationship between
food abundance and foraging frequency remains unknown in this species. We aimed at investigating the influence
of insects’ abundance on foraging by the Alpine swift during the breeding period. Fourteen birds of an Alpine swift
colony from Baden in Northern Switzerland were equipped with geolocators-dataloggers (gdls) to record flight
altitude and foraging effort (number of visits to the nest and hunting time used as proxy) during the whole
breeding period (May – August). At the end of the season, gdls from 9 birds (5 males and 4 females) out of 14 could
be retrieved for data analysis. The abundance of aerial insects near the swift’s colony was determined over the
whole breeding period with the help of radar technology.
Our data analyses show that the foraging frequency of swifts was influenced by the abundance of aerial insects,
with a mean ranging from 6 to 11 visits per day under low and high insects’ abundance, respectively. During the
feeding of the chicks, the mean hunting time (time between two visits to the nest) was 125 min (credible interval
95%: 91 – 174 min) and remained constant for all this time. Before hatching and after fledgling, the hunting time
was about 30 min longer (non-significant difference). Interestingly, the hunting time of the Alpine swift was not
significantly influenced by insects’ abundance in the air. This can be explained by the good weather conditions this
year or by a particular efficiency for the swifts to find food even in low insects’ abundance conditions. To our
knowledge, this is the first time that gdls and radar data are combined to establish behavioural patterns of a bird
species.
Effects of species and resource diversity on leaf litter decomposition in experimental aquatic
ecosystems
Fabienne Santschi, [email protected], eawag, Swiss Federal Institute of Aquatic Science and
Technology; Isabelle Gounand, [email protected], University of Zurich and eawag, Swiss Federal Institute
of Aquatic Science and Technology; Eric Harvey, [email protected], University of Zurich and eawag, Swiss
Federal Institute of Aquatic Science and Technology; Florian Altermatt, [email protected], University of
Zurich and eawag, Swiss Federal Institute of Aquatic Science and Technology
Litter decomposition is a major process in nutrient and resource turn-over and thus plays an important role in the
functioning of ecosystems. Theory suggests that diversity of decomposers as well as the functional diversity of leaf
litter affect the decomposition process. However, while a positive biodiversity-ecosystem relationship is well
established for primary producers, the biodiversity effect on decomposition is more debated. We conducted an
aquatic laboratory microcosm experiment with natural microbial decomposer communities to address how
resource biodiversity affects litter decomposition. We evaluated the influence of aquatic microbial activity, the
composition of decomposer communities as well as the quality and diversity of leaf litter on decomposition rates.
Litter quality and the composition of the organic litter stock influenced microbial activity and consequently the rate
of decomposition. Additionally, our results suggest that predator-prey dynamics within the microbial communities
have a large influence on the functioning of a whole ecosystem, as the presence of bacterivorous protists reduced
the decomposition process. These results highlight the importance of the composition and quality of organic litter
as well as the respective community of decomposers on the recycling of nutrients in aquatic systems.
85
Effects of temperature during early development on adult fitness traits
Martin A Schäfer, [email protected], University of Zurich
Differential survival during early development may play an important, but neglected, role in shaping allelic variation
encoding for traits exposed to natural or sexual selection at later life stages. Using a fine-grained temperature
gradient at the upper margin of the thermal tolerance curve, I explored sex-specific selection during development
in the dung fly Scathophaga stercoraria by comparing the size of non-hatched and hatched pupae. In female pupae
and adult flies I further quantified the development of an additional, fourth spermatheca, which is rarely expressed
in the field and entails fitness costs at the adult stage. Males had lower temperature-survival thresholds, but
survival was not related to body size within both sexes, indicating no physiological costs of growing large in a
species with male-biased size dimorphism. In females high temperatures induced the expression of the additional
spermatheca as a correlated side effect of fast extrinsic (environmental) and/or intrinsic (genetic) growth.
Interestingly, females that survived the pupal stage expressed the naturally rare phenotype more frequent implying
that antagonistic pleiotropy across developmental stages can contribute to the evolutionary diversification of
female sperm storage morphology.
Integration of species distribution models and field assessments for evaluating mountain forest
vegetation dynamics under climate change. Analysis over a 20 year time scale
Daniel Scherrer, [email protected], University of Lausanne; Stéphanie Massy, [email protected],
University of Lausanne; Pascal Vittoz, [email protected], University of Lausanne; Antoine Guisan,
[email protected], University of Lausanne
The ongoing climate warming leads to a growing need of spatially explicit information on expected changes in
species distributions and community compositions to allow efficient conservation planning and habitat
prioritisation. Species distribution models are amongst the most used techniques to assess the impact of climate
change on vegetation but only very few studies validate their projections with accurate field data, especially at the
community level. Here, we use environmental data and vegetation surveys from around 1990 to project the
expected changes in forest composition over the last 25 years. The projections were then validated on a randomly
selected subset of 92 plots revisited in summer 2014. Our results demonstrate that while we are able to predict
general trends for species richness, species turnover and shift of ecological conditions we fail at identifying the
forest areas most or least affected by climate change. There are several possible explanations for this lack of spatial
accuracy of the predictions including location errors, observer bias, inter-annual variation and stochasticity of local
colonisation and extinction events. Nevertheless, this study demonstrated that there is ample need for more
precise community models to allow meaningful conservation measures and planning.
86
Colonisation dynamics of a clonal pioneer plant on a glacier foreland inferred from spatially explicit
and size structured matrix models
Daniel Scherrer, [email protected], University of Lausanne; Peter Stoll, [email protected], University of
Basel; Jürg Stöcklin, [email protected], University of Basel
The regional distribution of a plant species is a result of the dynamics of extinctions and colonisations in suitable
habitats especially in strongly fragmented landscapes. Here, we studied the role of spatial dynamics of the longlived, clonal pioneer plant Geum reptans occurring on glacier forelands in the European Alps. We used
demographic data from several years and sites in the Swiss Alps in combination with wind dispersal data to
parameterise a matrix model for G. reptans to simulate extinctions, colonisations and spatial spread of established
populations on glacial forelands. We used different scenarios with varying germination rates, dispersal capabilities
and modes of spatial spread (seed-only vs. clonal reproduction), resulting in population growth rates (?) ranging
from 1.04 to 1.20. Our results suggest that due to the low germination rate (~1%) and the very limited seed
dispersal distances (99.8% of seeds are dispersed <5 m), G. reptans has a low probability of establishing new
populations and a very low spatial spread by seed dispersal alone. In contrast to the low rate of establishment, the
persistence of established populations is high and even populations of only a few individuals have an extinction
probability of less than 5% within 100 years. This high persistency is partly due to clonal reproduction via
aboveground stolons. Clonal reproduction increases the population size and contributes considerably to the spatial
spread of established populations. Our simulation results together with the known pattern of molecular diversity of
G. reptans indicate that the occurrence of populations of this species in the Alps is unlikely to be a result of recent
colonisations by long-distance dispersal, but rather a result of post-glacial colonisations by large migrating
populations that were fragmented when glaciers retreated.
The archetypal plant - what Goethe did not know at his time. Concept of an exhibition
Peer Schilperoord, [email protected], Verein für alpine Kulturpflanzen; Kathrin Studer-Ehrenscberger,
[email protected]
What can we learn from Goethe's concept of the <archetypal plant> nowadays? Goethe, co-founder of
comparative morphology, looked at the plant as a whole. Many of the results he presented have become obsolete
and are meanwhile only of historical interest. His methodological approach, his concept of metamorphosis, is still
valid and fruitful.
The central element in the exhibition is a model of a woody, dicotyledonous plant complementally to the classical
model of the herbaceous plant. The choice of this model is in accordance with the phylogeny in the angiosperms. It
differs in one essential element from the common model: the bud. The proposed model enables to study the
metamorphosis of 1. stem leaves into bud scales and 2. the qualitatively different metamorphosis of bud scales into
stem leaves. The first metamorphosis is a continuous one, the second shows a leap between the last scales and the
first stem leaf. The observer is stimulated to compare the sprouting bud and the just opened flower.
The leaf appears in this context not in his classical form with leaf base, petiole und blade. The nature of the leaf
includes both stem leaves and bud scales, both are part of a metamorphosis constituting the plant.
Stamen and carpel both have a leafy nature. They are also characterized by their ability to produce spores. The
spore producing ability cannot be derived from the nature of the leaf. Both, the leafy nature and the impulse to
produce spores leads to the formation of the stamens with the pollen sacs and to the formation carpels with the
ovules.
Further elements of the exhibition are among others: the diversity of leaf forms, leaf ontogenesis; settings of
course during ontogenesis; the growth mode of fern fronds and angiosperm leaves.
We want to enable the visitors a complementary view on the world of flowering plants.
Audiences: adults and pupils from the third grade of secondary school
Exhibition sites: botanical gardens, libraries, regional museums.
Responsible: Peer Schilperoord, biologist, Alvaneu (GR); Kathrin Studer, botanist, Bern.
87
Does a mycovirus affect virulence in the ash dieback pathogen Hymenoscyphus fraxineus?
Sandra Schneebeli, [email protected], University of Zurich; Carolina Cornejo, [email protected], WSL;
Daniel Rigling, [email protected], WSL
Ash dieback is an emerging tree disease in Europe caused by the ascomycete fungus Hymenoscyphus fraxineus.
Recently, a virus located in the mitochondria of the pathogenic fungus was detected called Hymenoscyphus
fraxineus mitovirus 1 (HfMV1). Mycoviruses are commonly found in all major groups of plant pathogenic fungi.
Some viruses were found to cause debilitation or reduce virulence in its fungal host thereby they have the potential
to be used as biocontrol agents. In this study, HfMV1 was further examined for its possible effects on virulence of
H. fraxineus. First, we found that HfMV1 was present in most of the fungal isolates collected in Europe including
high and low virulent isolates. To test if there is a relationship between virus sequence and fungal virulence we
sequenced 20 viral strains each from high virulent and low virulent fungal isolates. Phylogenetic and discriminant
analysis of principal components (DAPC) revealed the presence of three distinct groups of virus sequences
indicating that probably only three HfMV1 strains were introduced into Europe. The results further showed no
difference between “high virulent” and “low virulent” strains, indicating that HfMV1 doesn’t affect virulence of the
pathogen. HfMV1 might therefore belong to the vast majority of fungal viruses, which cause no symptoms to its
hosts.
Detection of invasive mosquito species using environmental DNA from water samples
Judith Schneider, [email protected], Department of Ecology and Evolution, University of Lausanne; Luca
Fumagalli, [email protected], Department of Ecology and Evolution, University of Lausanne; Olivier Glaizot,
[email protected], Museum of Zoology, Lausanne
Repeated introductions and the spread of some invasive Aedes mosquito species have been recorded on a large
scale in Europe these last years. These mosquitoes can present serious risks to public health as they have or may
develop vector competence for various diseases. While Aedes albopictus is a well-known vector for, e.g., dengue
and Chikungunya fevers, the vectorial competence of Aedes j. japonicus or Aedes koreicus is less established, but
they may for example transmit West Nile fever and Japanese encephalitis respectively.
Early detection of invasive mosquito species is crucial for successful eradication or control strategies. Traditional
monitoring methods, which consist in sampling eggs, larvae or adults are time consuming and are likely to miss
positive samples. Cryptic stages of some mosquito species may lead to misidentifications as well.
Here we developed and tested an environmental DNA (eDNA) approach for the detection of three invasive species,
based on water samples from the field. We compared two different methods. Environmental DNA was amplified
with species-specific primers and probes using quantitative real-time PCR. A subsample was additionally analysed
using group-specific primers and next-generation sequencing.
While the detection was possible for the three species with both methods, the species-specific approach proved to
be more sensitive. Advantages and disadvantages of both methods are discussed. Overall, eDNA is suitable for the
early detection and monitoring of invasive mosquitoes. The ease of water sampling allows the development of
citizen science methods for early detection of invasive species.
88
Assessment of the efficiency of natural hypovirulence for the biological control of chestnut blight
Janine Melanie Schwarz, [email protected], ETH Zürich; Daniel Rigling, [email protected], Swiss Federal
Research Institute WSL; Simone Prospero, [email protected], Swiss Federal Research Institute WSL
Chestnut blight disease caused by the ascomycete fungus Cryphonectria parasitica was accidentally introduced
from Asia to North America and Europe early in the 20th century. In contrast to the American chestnut (Castanea
dentata), which was subjected to a massive dieback, the European chestnut (Castanea sativa) has been able to
recover from the epidemic due to naturally occurring hypovirulence caused by infection of C. parasitica with
Cryphonectria hypovirus 1 (CHV-1). The virus can be transmitted vertically into asexually produced conidia and
horizontally via hyphal anastomosis between C. parasitica strains belonging to the same or closely related
vegetative compatibility (vc) types. In this study the efficiency of natural hypovirulence for the biological control of
chestnut blight was assessed in the field. Chestnut trees were therefore inoculated with hypovirus-free C. parasitica
isolates of known genotypes in two stands in Ticino, Switzerland. Half of the infections were conducted with a
common vc type (EU-1) and half with a rare vc type (EU-12). Canker development was periodically assessed and
bark samples were taken to isolate pure cultures of C. parasitica. Using vc types and microsatellite markers the
genotype of each isolate was assessed in order to find out whether new genotypes migrated into the cankers.
Additionally, the isolates were tested for hypovirus-infection and the RNA sequence of the virus was analyzed. We
hypothesize that (1) cankers will be infected by resident hypoviruses, (2) infection rates will be associated with the
presence of new genotypes in the cankers, and (3) cankers with the predominant vc type will be more efficiently
infected than cankers with rare vc types. We also assessed the effect of virus-infection on canker development. The
results of the currently ongoing analysis will be presented at the conference.
Expansion of Gene Families and Signature of Positive Selection Linked to Herbivory in Polyphagan
Beetles
Mathieu Seppey, [email protected], University of Lausanne; Marc Robinson-Rechavi, [email protected], University of Lausanne; Nadir Alvarez, [email protected], University of Lausanne
The order Coleoptera, commonly known as beetles, contains more than a quarter of all taxa recorded so far (ca.
350,000 species). The close relationship between beetles and land plants is often used as an explanation for this
prolific radiation. However, genomic signatures of such process have not been retrieved yet.
Here, we aimed at identifying whether diversification of herbivorous beetles was associated with evolutionary
features in genes relevant to the insect-plant interaction. We applied a comparative genomic approach involving
the two most specious beetle suborders, i.e., Adephaga, which contains mostly predacious species (ca. 40,000
species), and Polyphaga, which encompasses a majority of herbivorous species (ca. 300,000 species).
Using whole-genome and transcriptome data, we assessed two kinds of genomic changes in orthologous proteincoding sequences among 16 species belonging to the two suborders. First, we identified whether or not positive
Darwinian selection (PDS) was at work in each of those genes; second, we quantified the duplication level of gene
families in each suborder.
We focused on two categories of genes known to be involved in herbivorous insect metabolism, i.e., genes related
to the detoxification of, or targeted by, plant compounds produced to deter herbivores (e.g., cytochromes P450,
glutathione S-transferases, UDP-glycosyl transferases, and carboxylesterases) and digestive protease genes
expected to be a response to plant protease inhibitors.
We hypothesized that polyphagan beetles should display a higher number of PDS events and wider families for
these candidate genes, than adephagan beetles.
Preliminary results indicate that glutathione S-transferases, carboxylesterases, UDP-glycosyl transferases and serine
peptidase families might be larger in polyphagan vs. adephagan beetles. We also highlighted a larger number of
positively selected peptidase genes in Polyphaga than in Adephaga. These results represent a first evidence that
the association of polyphagan beetles with plants has dramatically shaped their genome and participated to their
spectacular diversification.
89
Testing for reproductive isolation between two geographically and genetically distant lake populations
in the haplochromine cichlid Astatotilapia burtoni
Kolja Smailus, [email protected], University of Basel; Walter Salzburger, [email protected],
University of Basel; Bernd Egger, [email protected], University of Basel
The event of speciation and the understanding of how it is driven by selection is a ubiquitous topic in biology.
Reproductive isolation may evolve as a by-product of the accumulation of differences between two geographically
distant populations. The radiation of East African cichlids in Lake Tanganyika is an important model for studying
patterns of speciation. Here, we focus on assortative mating patterns in a fish of the haplochromine tribe,
Astatotilapia burtoni, which occurs within Lake Tanganyika and surrounding rivers. We use a two-way female
choice setup with two geographically distant lake populations that genetically cluster differently, to assess if and on
which level reproductive isolation, or preferential mating, is present. We test female preference with visual contact
only using egg traps and video analysis of the activity of both, males and females, and the time spent of the female
with a respective male.
The results of this experiment should allow us to infer at which stage of the speciation continuum the populations
rest at present.
Soil biodiversity and ecosystem functioning and services in vineyards
Magdalena Steiner, [email protected], University of Fribourg; Sven Bacher, [email protected],
University of Fribourg; Anne-Laure Fragnière, [email protected], University of Fribourg
The BiodivERsA/FACCE-JPI project PromESSinG (www.promessing.eu) investigates the links between soil
management, soil biodiversity and ecosystem functions in vineyard ecosystems in five European countries (CH, F, D,
A, ROM). In standardized experiments replicated in each country, we investigate how different levels of plant cover
affect the diversity soil organisms and their community structure and function. Here, we present results from the
first study year (2015) obtained in Switzerland. In particular, we study how soil management practices affect the
diversity and community compositions of different groups of soil organisms, such as plants, the microbial
community, mesofauna and macrofauna. We also look at the effects of management on soil functions like soil
respiration and decomposition rates as well as nutrient regimes in the soils. Furthermore we relate the results to
different indicators of grape quality as an ecosystem service to the farmer. The ultimate aim of this study is to
advise on soil management to maintain high levels of grape quality while conserving microbial soil diversity and
functioning in vineyard ecosystems.
90
Thermal limits of ant assemblages along altitudinal gradients
Hanrong Tan, [email protected], University of Basel; Brigitte Braschler, [email protected],
University of Basel
Biotic interactions such as competition are conventionally thought to be the main structuring force behind ant
communities although environmental filters such as temperature may also play a role. Here we examine thermal
limits to movement in the laboratory and the temperature-dependence of foraging activity in the field. We
examine whether ant thermal physiology does indeed correlate with actual behaviour in the field. We measured
the upper critical thermal limits to coordinated movement (CTmax) of 27 ant species collected from 424 nests
distributed over 15 study sites along three different altitudinal gradients (Rigi, Schilthorn and Wasserfallen) in
Switzerland. Using altitude as a proxy for temperature, we examined whether assemblage means for CTmax
decrease with increasing altitude and repeated this analysis for the two most species rich genera (Formica and
Myrmica) separately. Assemblage means for CTmax do appear to decrease with increasing altitude. However, this
relationship was not statistically significant using assemblage means for CTmax. The separate analysis for Formica
and Myrmica was on the other hand, statistically significant. Sites at higher elevation did indeed have Formica or
Myrmica species with lower CTmax, indicating that local temperature may act as an environmental filter for some
species. We also examined whether CTmax differs among sites or transects for seven frequent species. While there
was substantial variation among individuals, CTmax did not differ among populations for any of the examined
species, indicating that local variation in CTmax may not be important when modelling species distribution for ants.
Functional assessment of soil quality & biodiversity indicators of urban gardens in Zurich
Simon Tresch, [email protected], Functional Ecology Laboratory, Institute of Biology, University of Neuchâtel;
Andreas Fliessbach, [email protected], Department of Soil Sciences, Research Institue of Organic
Agriculture (FiBL); Marco Moretti, [email protected], Biodiversity and Conservation Biology, Swiss Federal
Research Institute WSL; Claire Le Bayon, [email protected], Functional Ecology Laboratory, Institute of
Biology, University of Neuchâtel
Modern strategies to maintain and preserve urban green spaces and safeguard the soils should include key soil
functions providing ecosystem services, such as decomposition of organic matter, nutrient cycling and provision of
below and above ground habitat for living organisms.
This study, which is part of an interdisciplinary research project (www.bettergardens.ch), is aiming at assessing the
factors influencing soil quality and how they are related to functional soil biodiversity. Soil quality is assessed by
chemical (pH, heavy metals, nutrients, soil carbon and nitrogen), physical (aggregate stability, compaction, water
holding capacity, bulk density and grain size distribution) and biological (microbial biomass and soil respiration)
indicators. Soil biodiversity is analysed by sampling macrofauna (earthworms and large arthropods), mesofauna
(collembola) and by assessing the functional community distribution of the soil microfauna.
We will present an inventory of the garden types (home and allotment gardens) with increasing distance from the
urban centre and a gradient of structural richness, based on the analyses given above. In each garden a site under
permanent plant cover and another under annual plants is investigated. The role of soil microbiota in the
decomposition of plant material will be shown as a functional element of soils. We are using teabags (green tea and
rooibos tea) to assess the decomposition in situ and complement it by a substrate utilization assay (MicroResp)
under lab conditions.
Combined with information received from research areas of economy, sociology, and biodiversity, we are expecting
to relate our results to management factors that come out of a survey with garden owners and to the aboveground
biodiversity assessed in the same gardens simultaneously in this research framework.
91
Frequency and cellular mechanisms of parthenogenesis in haplodiploid animals
Casper van der Kooi, [email protected], University of Lausanne
Frequency and cellular mechanisms of parthenogenesis in haplodiploid animals
Casper van der Kooi and Tanja Schwander – University of Lausanne
The occurrence of female-producing parthenogenesis (hereafter: parthenogenesis) greatly varies between animal
taxa. In his seminal work, Bell (1982) estimated that on average 0.1% of the animals reproduce by means of
parthenogenesis. However, Bell’s estimate was not based on a detailed species list and the frequency of
parthenogenesis greatly varies among different animal groups. For example, whereas parthenogenesis is
exceedingly rare among vertebrates, it occurs frequently in many insect groups. Currently, there is no objective
estimate of the frequency of parthenogenesis for any invertebrate group.
In this review, we provide a first step towards an exhaustive list of obligate parthenogenetic animals. We focus on
animals that are characterized by haplodiploid sex determination (where males develop from unfertilized eggs and
females from fertilized eggs), because in this group of species parthenogenesis has been studied thoroughly. Where
known, the cellular mechanisms of parthenogenesis are summarized.
We find that parthenogenetic lineages exist in more than 300 haplodiploid species. We highlight that the
occurrence of parthenogenesis tremendously varies between taxa; in some genera more than 50% of the species
comprise parthenogenetic lineages. We furthermore show that the widely held belief of most parthenogens being
polyploids does not hold for haplodiploids and likely not for animals generally. Our review opens new perspectives
for studies on transitions between reproductive modes in animals.
References
Bell G (1982). The masterpiece of nature. The evolution and genetics of sexuality. London: Croom Helm.
Is there evidence for rapid evolution in a long-term grassland biodiversity experiment?
Sofia van Moorsel, [email protected], University of Zurich; Terhi Hahl, [email protected],
University of Zurich; Debra Zuppinger - Dingley, [email protected], University of Zurich; Philippine
Vergeer, [email protected], Wageningen University; Joop Ouborg, [email protected],
Radboud University; Bernhard Schmid, [email protected], University of Zurich
Previous studies have shown that plants that survived for eight years in species mixtures have been selected for
better performance in the species mixtures than in monocultures, and vice versa. Better performance of mixture
phenotype plants in species mixtures is likely due to selection pressures sorting out individuals that use overlapping
niches, leading to increased complementarity between plant species in terms of character displacement and
resource use, and finally, increased biodiversity effects over time. Thus, high- and low-diversity communities result
in selection for plant traits leading to different phenotypes. Arguably, differences between mixture and
monoculture phenotypes may be due to genetic divergence, a process called rapid evolution. However, it is
possible that epigenetic factors also play an important role.
To test this, we will measure both genetic and epigenetic variation in the offspring from plants from monocultures
and mixed communities (from the Jena Experiment) which were propagated in experimental monocultures and
mixed communities. For the genetic and epigenetic analysis of the mixture and monoculture phenotypes, we make
use of a reduced representation bisulfite sequencing (RRBS) technique that enables us to screen both genetic and
epigenetic variation in a cost-efficient and highly detailed way. Furthermore, we study selection for combining
ability, or the ability to function more complementarily with coexisting species, of the monoculture versus mixture
selected plant types. With this project, we want to start the exploration of the role of epigenetic and genetic
processes in the coexistence of species, a prime mechanism in conservation biology.
92
RechAlp.vd - a new support platform for transdisciplinary research in the Alpine region of the Vaud
Canton
Isaline von Däniken, [email protected], University of Lausanne, Faculty of geosciences and Environment;
Antoine Guisan, [email protected], University of Lausanne, Faculty of geosciences and Environment and
Faculty of Biology and Medicine; Stuart Lane, [email protected], University of Lausanne, Faculty of geosciences
and Environment
The RechAlp.vd project (von Däniken and al. 2014, 175-178), is the wish of the Faculty of Geosciences and the
Environment (FGSE) at the University of Lausanne (unil) to create a priority research area in the Alps. The aim is to
develop a support platform that encourages and maintains interdisciplinary research in a part of the Alps (Alps of
Vaud, ca. 700 km²). This research area in the Alp may become the most known and studied in Europe The support
platform contains an online geo-database storing and retrieving what data and metadata exist on datasets, projects
and activities in the research area. A portal is homed on the unil’s website at URL: http://rechalpvd.unil.ch and to
date contains more than 4000 metadata in the fields of natural sciences. This tool is available for everyone from
everywhere. The promotion and the introduction of the platform are currently in progress. It is now possible using
the RechAlp.vd portal to do the inventory of the data linked to the Alps of Vaud, to identify geographic or
environmental gaps in the existing information and to design complementary data sampling strategies. In this
regard, RechAlp.vd should open new scientific perspectives for research and teaching, especially in transdisciplinary
fields of natural sciences. Today, the platform RechAlp.vd opens to social sciences. A big work have to be done to
inventory all the projects, documents and metadata that exist in social sciences in the research area. The aim of this
opening is to involve all the unil Faculties in the RechAlp.vd project and to create more interdisciplinary between
researchers.
Inter-population variation in the exploratory behaviour in Asian common toad (Duttaphrynus
melanostictus) during metamorphosis
Mukta Watve, [email protected], University of Bern; Binoy V. V., [email protected], National Institute
of Advanced Studies, India
Understanding how individuals of a species, dramatically metamorphosing, shifting niches during the course of
development and surviving in ecosystems varying in selection pressures, fine-tune their personality traits can offer
insight to behavioural adaptation. The present study compared different components of exploratory behaviour in
tadpoles of Asian common toad, collected from two very different habitats, using an ‘open field’ apparatus. Our
first focal population was from a very shallow temporary rain puddle with no shade above, while tadpoles from
permanent artificial tank of 2 m depth, located below a large tree, formed the second. The comparison of
behavioural traits was conducted in four vital stages of development. Our result revealed that tadpoles from
puddle took very long time to initiate their exploration and spent very less time in searching the novel area of open
field, in comparison to their counterparts in the early period of development. However, no significant variation was
observed in the exploratory behaviour of both populations in the later stages of metamorphosis. It is possible to
say that the effects of early-life environment may be less pronounced in species that live in totally different
habitats pre- and post-metamorphosis although a much deeper inquiry is needed.
93
The role of epigenetics in adaptive processes in Tetrahymena thermophile
Vanessa Weber de Melo, [email protected], University of Zurich; Robert Lowe,
[email protected], Queen Mary University London; Paul Hurd, [email protected], Queen Mary University
London; Owen Petchey, [email protected], University of Zurich
Epigenetic variation may have a significant impact in evolutionary and adaptive dynamics, but its role in these
processes is not well understood. To clarify this, experiments in which populations of Tetrahymena thermophila
adapted to different conditions were performed. Gene expression patterns and the presence of histone
modifications were assessed. Nine replicate populations of T. thermophila were grown, starting at low densities
with population size rapidly increasing to carrying capacity. Populations were sampled at three different densities:
at medium density during exponential growth, close to carrying capacity and several generations at carrying
capacity, with three replicates per sample. The transcriptomes sampled at the same density were more similar to
each other than to transcriptomes sampled across densities. Gene expression analyses found 2599 differentially
expressed genes between samples during exponential growth and close to carrying capacity. Patterns of gene
expression were much more similar between the last two sampling points, with 292 genes differentially expressed.
Distribution of epigenetic marks appeared inconsistent with transcriptome patterns, with possible explanations
being explored. A similar experiment with more frequent sampling was performed in order to have a more precise
and detailed understanding of these dynamics as population density increases.
Plant-mediated above-belowground interactions are influenced by plant genotypic variation and soil
types
Zhenggao Xiao, [email protected], University of Neuchatel; Linhui Jiang, [email protected], Nanjing
Agricultural University; Sergio Rasmann, [email protected], University of Neuchatel; Manqiang Liu,
[email protected], Nanjing Agricultural University; Huixin Li, [email protected], Nanjing Agricultural University;
Feng Hu, [email protected], Nanjing Agricultural University
Recent work is showing that belowground biota can affect aboveground species interactions and community
structure via changes in plant metabolic pathways. For instance, root feeder can induced the accumulation of
defense hormones and secondary metabolites aboveground, and ultimately induce resistance against aboveground
herbivore attack. However, plant metabolic responses to herbivore attack are highly species specific and context
dependent. Classically, for instance, pathogens can increase the salicylic acid pathway, while herbivorous insects
tend to induce the jasmonic acid pathway in plants, and because the two pathways are antagonistic to each other,
this would generate trade-offs in plant resistance against different attackers. We here investigated whether rootfeeding nematode (Meloidogyne incognita)-induced foliar resistance vary according to different soil amendments
(inorganic vs organic), and whether it varies depending on the different genotypes of plants that are modified in
the jasmonic acid biosynthesis. We found that nematode-induced root galls was reduced under organic
amendment than under inorganic amendment. Regardless of amendment type, there were significantly fewer galls
on the JA over-expressing genotype (35S) than on the wild-type (Wt) and than on the JA-deficient genotype (spr2).
Moreover, there were different antagonistic interactions between the SA and JA signaling pathways and defense
responses among tomato genotypes particularly under organic amendment. In the Wt and 35S genotypes, organic
amendment significantly increased nematodes-induced foliar JA concentration, thus up-regulating the protease
inhibitors (PIN1, PIN2) gene expression and down-regulating the PAL gene expression. However, it decreased
nematode-induced foliar SA concentration. Conversely, in the spr2 genotype, foliar JA concentration was quite low
but SA concentration was notably increased by organic amendment, and the SlWRKY70 transcript levels upregulation further triggered the suppression of JA-induced defense response. Our results suggest that different soil
amendments and plant genotypic variation modulate root herbivore-mediated changes in aboveground
phytohormonal signaling pathways, thus likely changing plant responses to aboveground colonizers, and ultimately
how plants are protected in crop fields.
94
Diapause induction dynamic in several Swiss black scavenger fly species (Diptera: Sepsidae), evidence
from the lab and the field
Valérian Zeender, [email protected], University of Zurich
Diapause is having a major influence on insects’ life history. A better understanding of diapause phenology could
greatly improve field methodology and life-history characterization.
It is known temperature and photoperiod are the major environmental cues used by insects to determine the best
timing to overwinter. But, it is not clear what is the relative importance of each of these variables and also at which
life-stage individuals are sensitive to diapause induction cues. We addressed these questions using several species
of black scavenger flies (Diptera: Sepsidae: Sepsis), which is an increasingly used model species in ecology and
evolutionary biology. It has been previously shown that one sepsid fliy (S. cynipsea) enters reproductive diapause at
the adult stage, saving energy by storing lipids (diapause pathway) rather than producing eggs (reproduction
pathway). In order to disentangle the effect of temperature and photoperiod, we assigned females individuals of
five species of the Sepsis genus to four combinations of temperature and photoperiod. Additionnaly, to study a
putative life-stage effect, flies were assigned to the treatments at four different life-stages.
In this study, we show that: (1) there is an important variation in diapause induction cues among the Sepsis genus
and that (2) conversely to previous beliefs, temperature is as important as photoperiod regarding diapause
induction. (3) No temperature × photoperiod interaction was observed in any of the studied species nor (4) any lifestage effect. We show that even closely related species use different environmental variables as diapause induction
cues and then give additional hints to study the diapause process in the field for the Sepsis genus.
Life-history response to environmental change revealed by resurrected rotifers from a historically
polluted lake
Naomi Zweerus, [email protected], Institute of Evolutionary Biology and Environmental Studies, University of
Zurich, Zurich, Switzerland; Stefan Sommer, [email protected], Institute of Evolutionary Biology and
Environmental Studies, University of Zurich, Zurich, Switzerland; Diego Fontaneto, [email protected], National
Research Council, Institute of Ecosystem Study, Verbania Pallanza, Italy; Arpat Ozgul, [email protected],
Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
Past episodes of environmental pollution can significantly influence population dynamics and corresponding microevolutionary processes. In species that produce dormant stages, methods of resurrection ecology allow
investigation of such processes in retrospect by exposing newly hatched individuals, originating from different
pollution periods, to varying levels of pollution.
In this study, populations of two rotifer species, Brachionus calyciflorus and B. urceolaris, were resurrected from
temporally distinct sediment layers of a subalpine lake (Lake Orta, Italy), representing periods of high, medium and
low copper concentration caused by anthropogenic pollution and recovery. Experimental cultures were then
exposed to three levels of copper and an unpolluted treatment over a period of 14 days. Stage structure and
population densities were monitored at 48h intervals. Results showed interspecific, intraspecific and clonal
differences in life-history responses, indicating high sensitivity to selection pressures. Population fluctuations
showed similar patterns within clones coming from the same period, however some populations crashed after
investing in sexual reproduction. Populations from the lake-recovery period experienced the lowest population
growth rate and maximal density compared to populations from the peak- and the post-pollution periods.
Moreover, both species showed distinct patterns of population densities, most likely caused by different modes of
reproduction. When the majority of individuals reproduced asexually, populations reached maximal densities
earlier compared to populations dominated by mictic individuals.
The observed differences in copper tolerance and signs that historically experienced pollution levels may have
affected the degree of investment in sexual reproduction suggest a potential for adaptation. By using a biodemographic perspective in combination with an experimental approach, our analysis of resurrected Lake Orta
rotifers provides insight into the life-history responses of an aquatic invertebrate in an ever-changing environment.
95
List of
participants
Adam
Aeschbacher
Allan
Altermatt
Alther
Ammann
Andriollo
Annen
Apothéloz-Perret-Gentil
Arlettaz
Asse
Augustinus
Bakhtiari
Barras
Barratt
Barreaux
Bast
Baur
Behr
Bento
Berli
Bersier
Binning
Binti Mohd Assaad
Bizet
Blanckenhorn
Bonnet
Bonny
Bont
Booksmythe
Bosco
Bouchenak
Bouchenak Khelladi
Bouchenak-Khelladi
Bouquet
Braschler
Braunisch
Broennimann
Brugger
Bshary
Buckley
Buckley
Buri
Busso
Cappelli
Castro
Cauwet
Cavoto
Cermakova
Celine
Jonathan
Eric
Florian
Roman
Matthias
Tommy
Melanie
Laure
Raphaël
Daphné
Benno
Mojtaba
Arnaud
Chris
Antoine
Jens
Julian
Dominik
Gilberto
Barbara
Louis-Felix
Sandra
Norfarhan
Elisabeth
Wolf
Timothée
Laura
Zoe
Isobel
Laura
Yanis
Yanis
Yanis
Yaëllw
Brigitte
Veronika
Olivier
Sandra
Redouan
James
Yvonne
Aline
Juan Pablo
Seraina
Isabelle
Lucie
Elisa
Kristina
Université de Genève
University of Bern
University of Bern
University of Zuirch and Eawag
Eawag
University of Basel
University of Geneva
University of Neuchâtel
University of Geneva
University of Bern
University of Lausanne
CABI
University of Neuchatel
University of Bern
University of Basel
University of Neuchâtel
University of Lausanne
University of Zurich
University of Zurich
University of Basel
University of Basel
University of Fribourg
University of Neuchatel
ETH Zurich
University of Geneva
University of Zürich
University of Zurich
University of Lausanne
University of Bern
University of Zurich
University of Bern
University of Zurich
University of Zurich
University of Zurich
University of Neuchâtel
University of Basel
University of Bern
University of Lausanne
University of Bern
University of Neuchâtel
ETH Zürich
Trinity College Dublin
University of Lausanne
University of Zürich
University of Bern
University of Lausanne
University of Geneva
University of Lausanne
University of Geneva
96
Chapuisat
Chardon
Chebib
Choudhury
Christe
Cianfrani
Cibois
Colombo
Cornioley
Cozzarolo
Crameri
Croll
Csergo
Currat
Dakos
Dällenbach
D'Amen
Davydov
de La Harpe
Delhaye
Dermond
Descombes
DeSoto
Di Cola
Diane
Doenz
Dosch
Dreiss
Ducouret
Ducret
Dufresnes
Dulex
Dumont
Dupuis
Durmaz
Ecker
Egger
El Taher
Michel
Nathalie
Jobran
Rimjhim Roy
Philippe
Carmen
Alice
Marco
Tina
Camille-Sophie
Silvio
Daniel
Ana Maria
Mathias
Vasilis
Laura
Manuela
Iakov
Marylaure
Jessica
Philip
Patrice
Lucía
Valeria
Maitre
Carmela
Oliver
Amélie
Pauline
Valérie
Christophe
Nicolas
Guillaume
Cindy
Esra
Klaus
Bernd
Athimed
University of Lausanne
WSL
University of Zürich
University of Neuchatel
University of Lausanne
University of Lausanne
Natural History Museum Geneva
University of Basel
University of Zurich
University of Lausanne
University of Bern
ETH Zurich
Trinity College Dublin
University of Geneva
ETH Zurich
University of Bern
University of Lausanne
University of Lausanne
University of Fribourg
University of Lausanne
Eawag and University of Bern
WSL / ETH
University of Coimbra
University of Lausanne
University of Lausanne
Eawag and University of Bern
University of Bern
University of Lausanne
University of Lausanne
University of Lausanne
University of Lausanne
University of Lausanne
University of Lausanne
University of Lausanne
University of Lausanne
WSL
University of Basel
University of Lausanne
Emmanuel
Emmenegger
Erkosar
Espirito Santo
Fasel
Fässler
Fazan
Feller
Fernandes
Ferrari
Fisler
Fitze
Flatt
Defossez
Tamara
Berra
Natacha
Nicolas
Fabio
Laurence
Anna
Rui
Alice
Lisa
Patrick S.
Thomas
University of Neuchatel
Swiss Ornithological Institute
University of Lausanne
University of Basel
University of Bern
ETH Zürich
University of Fribourg
University of Bern and EAWAG
University of Lausanne
University of Bologna
University of Bern
University of Lausanne
University of Lausanne
97
Fontcuberta
Fontes
Formenti
Fouche
Frey
Fronhofer
Fumagalli
Gaigher
Gaille
Ganser
Ganz
Garnier
Garratt
Garschall
Genzoni
Gerber
Gerchen
Ghali
Ghazoul
Giesen
Glaizot
Glauser
Goebel
González-Forero
Goudet
Gounand
Gourgoulianni
Graham
Gray
Grbic
Gu
Guillaume
Guillebeau
Guillemin
Guisan
Guyer
Guyot
Hagmann
Hale
Hartikainen
Hartmann
Harvey
Heckel
Hefti
Helfenstein
Hertaeg
Hertl
Herzog
Holderegger
Humann-Guilleminot
Humbert
Huynh
Amaranta
Inês
Ludovico
Simone
David
Emanuel
Luca
Arnaud
Aurore
Dominik
Kathrin
Aurélie
Rhéa
Kathrin
Eléonore
Nina
Jörn Frederik
Karim
Jaboury
Athene
Olivier
Alexandra
Julien
Mauricio
Jerome
Isabelle
Natalia
Catherine
Sarah
Djordje
Langyu
Frédéric
Mélanie
Pauline
Antoine
Anouk
Claire
Reto
James
Hanna
Fanny
Eric
Gerald
Hélène
Fabrice
Corinne
Matthias
Chantal
Rolf
Ségolène
Jean-Yves
Stella
University of Lausanne
Eawag
University of Neuchâtel
ETH Zurich
WSL
Eawag
University of Lausanne
University of Lausanne
University of Lausanne
University of Bern
University of Zürich
University of Zurich
Conservatoire et Jardin Bot de GE
University of Lausanne
University of Lausanne
University of Zürich
University of Lausanne
University of Lausanne
ETH Zurich
University of Zurich
Museum of zoology
University of Bern
University of Lausanne
University of Lausanne
University of Lausanne
University of Zurich / Eawag
University of Zurich
Stony Brook University
University of Fribourg
University of Geneva
University of Basel
University of Zürich
Eawag
University of Lausanne
University of Lausanne
University of Bern
University of Bern
University of Basel
University of Bern
Eawag
ETH Zürich
University of Zurich
University of Bern
University of Bern
University of Neuchâtel
ETH Zürich
Eawag / ETH
University of Bern
WSL
University of Neuchâtel
University of Bern
University of Neuchâtel
98
I'Anson Price
Ihle
Indermaur
Iyer
Jacot
Jardim de Queiroz
Jaron
Jeannin
Jeffries
Jenkins
Jokerud
Jornod
Joye
Kaech
Kapun
Kaufmann
Keller
Keller
Kergunteuil
Khelifa
Kleinspehn
Klopfstein
Knauer
Koch
Kokko
Koubinova
Krishnan
Larose
Laura
Laurentino
Lavanchy
Le Gros
Lemoine
Lessard-Therrien
Lewington-Pearce
Li
Li
Liégeois
Linder
Link
Lischer
Loiseau
Lommen
Losapio
Luder
Luepold
Lüpold
Ma
Machado
Mahdjoub
Marcionetti
Masó Ferrerons
Robbie
Kate
Alex
Srignanakshi
Alain
Luiz
Kamil
Alexandra
Daniel
Tania
Mari
Maïwenn
Patrick
Heidi
Martin
Joshka
Laurent
Lukas
Alan
Rassim
Clemens
Seraina
Anina
Eva
Hanna
Darina
Parvathy
Chloé
Clément
Telma
Guillaume
Ariane
Mélissa
Malie
Leah
Xiang-Yi
Xinji
Maud
Peter
Vivian
Lukas
Oriane
Suzanne
Gianalberto
Katrin
Shannon
Stefan
Wen-Juan
Talita
Hayat
Anna
Guillem
University of Lausanne
University of Zurich
Agroscope
University of Zurich
University of Bern
University of Geneva
University of Lausanne
University of Neuchâtel
University of Lausanne
University of Lausanne
University of Bergen
University of Neuchâtel
University of Lausanne
ETH and Eawag
University of Lausanne
UNIL
University of Lausanne
University of Zurich
Functional Ecology Laboratory
University of Zurich
University of Bern
University of Bern
University of Zurich
University of Zurich
University of Zurich
University of Lausanne
ETH Zurich
University of Lausanne
University of Lausanne
University of Lisbon
University of Lausanne
Muséum National d'Histoire Na.
University of Zurich
University of Bern
Queen Mary University of London
Max Planck Institute
University of Lausanne
University of Lausanne
University of Zürich
University of Fribourg
University of Bern
University of Lausanne
University of Fribourg
University of Zurich
University of Bern
SUNY
University of Zurich
University of Lausanne
University of Lausanne
University of Zurich
University of Lausanne
IPE-CSIC
99
Massa
Mathé-Hubert
Matteodo
Mausbach
Mayr
McGee
Meier
Meier
Melliger
Menz
Meyer
Meyer
Montoya-Burgos
Moretti
Moser
Mushegian
Mustermann
Naciri
Nagelmüller
Nuotclà
Odermatt
Ortiz-Rodriguez
Page
Papa
Parain
Parejo
Parreno
Pauquet
Pena Venegas
Perret
Perrin
Petitpierre
Pichon
Pinto
Pöll
Pradervand
Quilodrán
Quintero
Rajkov
Ramel
Randin
Rasmann
Resano
Retel
Reyer
Rieder
Ritschard
Rivera-Rivera
Robinson-Rechavi
Roche
Roder
Rodrigues
Carolina
Hugo
Magalì
Jelena
Barbara
Matthew
Eliane
Joana
Ramona
Myles
Sandro
Joana Beatrice
Juan
Marco
Florian
Alexandra
Ralf
Yamama
Sebastian
Jon Andreja
Jannic
Damian
Paul
Yvan
Elodie
Melanie
Maria Alejandra
Gaëlle
Ricardo Alexander
Mathieu
Nicolas
Blaise
Noémie
Eric
Nestor C.E.
Jean-Nicolas
Claudio
Fredy
Jelena
Martina
Christophe
Sergio
Jaime
Cas
Uli
Nastassja
Eva
Carlos
Marc
Domnique
Stefanie
Nicolas
University of Lausanne
Eawag - ETH
University of Lausanne
University of Zurich
University of Bern
Eawag
Agroscope
Eawag / University of Bern
University of Basel
University of Bern
University of Bern
WSL
University of Geneva
WSL
University of Bern and EAWAG
University of Basel
FU Berlin
Conservatoire et Jardin Bot de GE
University of Basel
University of Bern
University of Bern
ETH Zürich / WSL
Agroscope
University of Geneva
University of Fribourg
University of Bern
University of Zurich
University of Basel
University of Lausanne
Conservatoire et Jardin Bot de GE
University of Lausanne
University of Lausanne
University of Bern
University of Lausanne
University of Basel
Station Ornithologique Suisse
University of Geneva
University of Neuchâtel
University of Basel
University of Zurich
University of Lausanne
University of Neuchâtel
University of Bern
University of Bern
University of Zurich
University of Bern
University of Bern
University of Geneva
University of Lausanne
University of Neuchatel
University of Bern
University of Lausanne
100
Rodrigues
Rogivue
Rohner
Rohr
Rolland
Roulet
Ruedi
Sahli
Salzburger
Sandau
Santschi
Savolainen
Saxenhofer
Schäfer
Scherrer
Schilperoord
Schmid
Schmid
Schmidt
Schneebeli
Schneider
Schwander
Schwarz
Séchaud
Selz
Seppey
Serrano Serrano
Silva
Singh
Smailus
Soliveres
Sonnay
Spasojevic
Stapley
Steiner
Stephan
Stephenson
Stieger
Stillwell
Stitelmann
Studer
Sun
Tan
Thoma
Thompson
Tilquin
Tomasini
Toprak
Toups
Tresch
triki
Troxler
Marisa
Aude
Patrick
Rudolf P.
Jonathan
Albertine
Manuel
Christophe
Walter
Nadine
Fabienne
Vincent
Moritz
Martin A
Daniel
Peer
Sarah
Max
Lisanna
Sandra
Judith
Tanja
Janine Melanie
Robin
Oliver
Mathieu
Martha Liliana
Nuno
Randeep
Kolja
Santiago
Vincent
Tamara
Jessica
Magdalena
Claudia
Jessica
Binia
R. Craig
Robert
Kathrin
Yan
Hanrong
Marco
Graham
Anaïs
Matteo
Zeynep
Melissa
Simon
zegni
Aline
University of Lausanne
WSL
University of Zurich
University of Fribourg
University of Lausanne
SVSN
Natural History Museum Geneva
University of Lausanne
University of Basel
University of Fribourg
Eawag
Imperial College London
University of Bern
University of Zurich
University of Lausanne
Verein für alpine Kulturpflanzen
University of Lausanne
University of Zurich
University of Bern
University of Zurich
University of Lausanne
University of Lausanne
ETH Zürich
University of Lausanne
Eawag
University of Lausanne
University of Lausanne
University of Geneva
Amity Institute of Wildlife Science
University of Basel
University of Bern
SVSN
University of Bern
ETH Zürich
University of Fribourg
University of Neuchâtel
ETH Zürich
University of Bern
University of Lausanne
HEPIA
University of Bern
University of Fribourg
University of Basel
University of Bern
University of Lausanne
University of Zürich
University of Bern
University of Genev
University of Lausanne
University of Neuchâtel
University of Neuchâtel
University of Bern
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Unternährer
Uva
Valeria
van Benthem
van der Kooi
van Klink
van Moorsel
van Santen
van Santen
Vasiljevic
Veltsos
Venail
Verde Arregoitia
Vierbuchen
Voillemot
von Däniken
Watve
Weber
Weber de Melo
Wegmann
Widmer
Wos
Wubs
Xiao
Yamada
yan
Yek
Zahnd
Zanatta
Zander
Zeender
Zeller
Zellweger
Zingg
Zini
Zoller
Zweerus
Debora
Vera
Bucher
Koen
Casper
Roel
Sofia
Marit
Marit
Nina
Paris
Patrick
Luis
Maddalena
Marie
Isaline
Mukta
Alexandra
Vanessa
Daniel
Lukas
Guillaume
Matthias
Zhenggao
Kana
zheng
Sze Huei
Sacha
Florian
Axel
Valérian
Michael
Florian
Silvia
Marco
Leana
Naomi
University of Bern
University of Lausanne
ex-Université de Lausanne
University of Zurich
University of Lausanne
University of Bern
University of Zurich
University of Zürich
University of Zürich
University of Zurich
University of Lausanne
Université de Genève
Natural History Museum Bern
University of Bern
University of Lausanne
University of Lausanne
University of Bern
University of Basel
University of Zurich
University of Fribourg
University of Basel
University of Neuchâtel
University of Neuchatel
University of Neuchatel
UNIL
University of Lausanne
University of Lausanne
University of Lausanne
Université de Liège
University of Fribourg
university of zürich
University of Neuchâtel
ETHZ and WSL
University of Bern
UNIL
University of Bern
University of Zurich
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Partners and sponsors
The conference is organized on behalf of
Swiss Academy of Sciences
Swiss Botanical Society
Swiss Zoological Society
Swiss Systematics Society
Swiss representative of the International Biogeography Society
Swiss chapter of the Society for Conservation Biology
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