Download in plant populations - Stockholms universitet

Local adaptation and life history
differentiation in plant populations
by
Tove von Euler
Supervisor:
Johan Ehrlén
Plants & Ecology
Plant Ecology
2009/6
Department of Botany
Stockholm University
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Plants & Ecology
Plant Ecology
Department of Botany
Stockholm University
S-106 91 Stockholm
Sweden
© Plant Ecology
ISSN 1651-9248
Printed by Solna Printcenter
Cover: Primula farinosa, Dröstorp, Öland. Photo by Tove von Euler
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Summary
Terrestrial plants display a wide range of adaptations to their local environment. Phenotypic
responses to environmental conditions select for genetic change and may result in altered
patterns of life history, such as increased reproductive investment in response to
environmental stochasticity. Regarding the selective agents on life history differentiation,
abiotic and biotic components have been found to act on different temporal and spatial scales.
Abiotic factors, such as moisture, soil conditions and exposure usually remain largely
unchanged over long periods of time and adaptations to climatic features often follow clinal
patterns along large geographical scales. Selection by biotic components on the other hand
tends to display a more mosaic pattern, both temporally and spatially. In this paper, I will
review and discuss some of the work performed on local adaptation to different environmental
variables in terms of alterations in life history strategies among plant populations. I will focus
on soil properties, climatic effects, and biotic interactions and discuss the relative impact of
these factors on different life history traits. I will also discuss possibilities and constraints of
the methods used to detect local adaptation in plant populations.
Sammanfattning
Landväxter uppvisar en rad anpassningar till sin lokala miljö. Fenotypiska responser till den
lokala
miljön
selekterar
för
genetiska
förändringar
och
kan
leda
till
ändrade
livshistoriemönster. Dessa kan ta sig uttryck i t ex ökad satsning på reproduktion kontra
tillväxt till följd av stokastiska miljöförhållanden. Selektion för livshistoriestrategier kan ske
på olika skala beroende på vilka miljöparametrar som ligger bakom selektionen. Abiotiska
faktorer, såsom fuktighet, markförhållanden och exponering är ofta relativt konstanta under
lång tid, medan den biotiska miljön ofta ter sig mer mosaisk i tid och rum. Jag kommer i den
här uppsatsen att sammanfatta ett antal studier som gjorts av lokal anpassning i
livshistorieegenskaper hos växtpopulationer. Jag har valt att fokusera på markförhållanden,
klimatfaktorer och biotiska interaktioner och den relativa effekt dessa faktorer har på olika
livshistoriekaraktärer. Jag kommer också att diskutera möjligheter och begränsningar med de
forskningsmetoder som tillämpas för att studera lokal anpassning hos växtpopulationer.
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Introduction
During the past century, the environment has been exposed to great changes, such as
intensified land use and climate change. Although it might be argued that the changes
observed today occur at unnatural speed, occasional events of rapid environmental change
have been present throughout the earth’s history, altering the conditions and selective
pressures on its inhabitants. Thus, from an evolutionary perspective, the ability to adapt to
new conditions is crucial for the survival and reproduction of organisms (Niklas 1997).
Across the globe, terrestrial plants display a wide range of adaptations to their local
environment. Selective factors contributing to these local adaptations include variation in the
local abiotic (edaphic, climatic) and biotic (mutualists, pathogens, herbivores) environment,
as a consequence of either natural or human induced forces (White 1984; Joshi et al. 2006).
Features such as growth, fecundity and mortality may be affected by various environmental
factors acting together on the individual plant, shaping the demography and life history of
plant populations (Stearns 1992; Kalisz & Wardle 1994). Moreover, abiotic and biotic
components of the environment have been found to exert selection at different temporal and
spatial scales. Abiotic factors, such as moisture, soil conditions and exposure usually remain
largely unchanged over long periods of time, thus acting on long temporal scales. Spatially,
however, soil properties, such as nutrients and soil water content, tend to act on relatively
small scales. Adaptations to climatic features (temperature, precipitation etc.) often follow
clinal patterns along large geographical scales (Olsson & Ågren 2002; Dahlgren et al. 2007;
Macel et al. 2007). Here, the temporal scale may be shorter, with large climatic fluctuations
among years. Selection by biotic components tends to display more mosaic pattern, both
temporally and spatially, because the selective agents are likely to display high dispersal rates,
and also because the biotic environment itself may be subject to selection (Agrawal et al.
2006; Crémieux et al. 2008).
The selective impact of environmental properties on plant populations will depend on several
factors such as genetic diversity within the population, the extent of gene flow, dispersal
pattern and demography. Different selection pressures exerted by different environments will
result in genetic heterogeneity. Furthermore, abiotic factors such as elevation, exposure, and
moisture availability may act as barriers to gene flow, enhancing genetic differentiation
among semi-isolated or isolated populations. Together these factors determine the rate at
which adaptation can proceed (Davis et al. 2005).
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In this paper, I will review and discuss some of the work performed on local adaptation to
different environmental variables in terms of alterations in demography (population age- or
size structure and growth rate) and life history strategies (Age and size at maturity, number
and size of offspring, reproductive lifespan and ageing) among plant populations. From the
wide range of possible natural and anthropogenic environmental factors selecting for local
adaptation, I have chosen to focus on soil properties, climatic effects, and biotic interactions. I
will proceed to discuss the relative impact of these factors on different life history traits.
Finally I will also discuss possibilities and constraints of the methods used to detect local
adaptation in plant populations.
Adaptation of life history traits
Phenotypic responses to environmental circumstances select for genetic change and may
result in altered patterns of life history. For instance, high or variable mortality may generate
selective pressure toward early reproduction, high fecundity and few reproductions (Roff
2002). A central part of a species life history strategy is its reproductive pattern. Under
selection for increased reproductive investment, many plants face arrested vegetative growth.
In the process of allocation to features of growth and reproduction, the meristem of a plant
may either differentiate into reproductive tissue, eliminating further growth or continue to
grow vegetatively. Thus an increased allocation to one of the two will occur at the expense of
the other. This phenomenon is central to life history theory and is referred to as trade-offs
(Stearns 1992; Roff 2002). An altered environment may lead to an alteration in the relative
parting of resources, changing the life history of the plant population and resulting in local
adaptation.
Plants display a number of reproductive strategies. At one extreme, some species reproduce
only once and then die (semelparity), at the other, there are species that live and reproduce
during hundreds of years (iteroparity). This variation in reproductive pattern enables plant
populations to persist in many different types of environments. In environments with high or
variable size-independent mortality, early reproduction, high fecundity, and few reproductions
will be selected for. Furthermore, selection for long life, late maturity and many reproductions
may occur in environments where the survival is size-dependent. Under these conditions, it is
crucial to rapidly attain a large size to ensure survival before reproducing (Roff 2002).
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Another important feature of plant life histories is the timing of reproductive events within
growing seasons. Particularly in a seasonal environment, the onset and duration of flowering
are major determinants of reproductive success. The benefits of flowering early, such as the
possibility of having a longer flowering period, must be weighed against the drawbacks,
sometimes involving greater risks of pre-reproductive mortality due to unfavorable weather.
For species where the generation time is short relative to the growing season, it will be
beneficial to have an extra generation within the same growing season (bivoltine species).
Also, in areas with large variation in the length of the growing season, some species might
display two different strategies; one variety with two generations within the same growing
season, and one with only one generation per growing season (partially bivoltine). This
pattern will increase fitness in years when the growing season is long, but will decrease
fitness by means of high mortality and low reproduction in years with a shorter growing
season. Conversely, in species that have long generations relative to season length, variation
in development time will be favored when the length of the growing season is variable (Roff
2002).
Methods of detecting local adaptation
The relationships between biotic or abiotic factors and geographic variation in life-history
traits are often used to infer genetic differentiation as an adaptive response to environmental
factors (Mazer & LeBuhn 1999). In reviewing a number of articles on the subject of local
adaptation in plant populations, I have come across several methods used to detect local
adaptation. Many of them are observational, where plant populations have been monitored
over spatial and temporal scales, and analyzed with aspect to various life history traits in
relation to environmental factors. Using large enough samples, it is possible to draw proper
conclusions on plant responses. However, it may be difficult to establish causal relationships
based on observation alone. Therefore, these methods might be most useful when predicting
possible plant-environment relationships. Using greenhouse or common garden experiments,
where plant material is collected from the field and grown under common and controlled
conditions, the possibility of detecting local adaptation is greater than in observational studies,
since many environmental variables can be excluded from the study. Hence, differences
observed between populations grown in a common environment most likely represent genetic
differentiation. One drawback of this method, though, is that the conditions in a greenhouse or
common garden are often markedly different from field conditions, and trait functions
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observed in the controlled environment may not be present in the field, which again might
make interpretation difficult. A time-consuming, but often rewarding method is to perform
reciprocal transplantations in the field. Investigating plant population responses to local vs.
foreign conditions, any local adaptation should be expressed as home-site advantage of local
populations. In this way, one may be able to determine whether genetic differentiation
observed among populations actually represents an adaptive response to environmental
selective pressure (Mazer & LeBuhn 1999). In some cases, for instance when dealing with
extremely rare species, it may not be justified to perform experiments on the species, risking
contributing to its extinction. There may also be other financial or practical constraints to
performing reciprocal transplantations. In these cases, using experimental modeling may be a
suitable method. Several models of this kind have been developed, and many are used to
make predictions about future responses of plant populations to changes in their environment.
When testing for local adaptation by means of reciprocal transplantation, there are two
commonly used approaches. One is the ‘Local vs. foreign’ approach, according to which the
home population will always perform better compared with foreign populations at the home
site. The other approach is the ‘Home vs. away’ approach, where any population should
always perform better at its home site than at any other site (Kawecki & Ebert 2004).
According to Kawecki, the former criterion is preferred, since it deals directly with divergent
natural selection acting on genetic differences in relative fitness within habitats. Thus, traits
that provide an advantage under local environmental conditions should be selected for.
However, these traits may perform equally well or even better in other habitat types. In the
home vs. away approach, the effects of divergent selection may be difficult to separate from
differences in habitat quality; A genotype that is optimally adapted to a poor-quality habitat
may still perform better in a resource-rich habitat, although it is only able to outperform other
genotypes in its resource-poor home-environment.
Effects of soil properties
Soil quality is of great importance to plant growth and persistence. It provides plants with the
necessary mineral nutrients, water, and oxygen, and supports the root system that absorbs and
transports these substances to the aboveground parts of the plant (Black 1957). Variation in
soil properties has been reported to affect plant performance on scales of only a few
centimeters (Argyres & Schmitt 1991). Examples of soil characteristics that may vary
between environments are texture, nutrients, moisture and biotic content. In many cases it
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may be difficult to separate these features, since they are strongly linked together. For
example, the nitrogen content of the soil is partly determined by plants and microorganisms,
which in turn are affected by temperature and water supply (Black 1957).
Soil texture
Soil texture can roughly be divided into three categories: Sand, silt and clay, where sand
represents the coarsest soil type and clay the finest (Hansen 1926; Black 1957). Soil texture
mainly imposes an indirect effect on plant performance in that it affects water availability.
Which soil type is most profitable to a plant is somewhat ambiguous, in that, on the one hand,
fine-textured soil has a higher water-retaining capacity, which may limit the risk of severe
drought. Meanwhile, in coarse-grained soil, water is more easily accessible to the plants, but
is also more rapidly lost through drainage. It is therefore difficult to determine the amount of
water that is actually available to the plants judging only from soil water content (Hansen
1926; Sala et al. 1988). A model of soil water accessibility that also takes into account the
climatic circumstances is the inverse-texture hypothesis, according to which plant
communities growing on coarse textured soils should have higher above-ground net primary
productivity (ANPP) in arid conditions, whereas in humid environments, the relationship
should be reversed (Noy-Meir 1973).
The effect of soil texture on plant populations has also been shown to vary with seasons. In
order to study variation in Bromus tectorum performance in relation to soil type, Miller et al.
(2006) manipulated water and nutrient availability across a range of soils and measured
various plant traits, such as establishment and seasonal growth rates. Performance was poorer
on sandy soils during the wet fall and winter season but greater during the dryer spring
season, indicating a seasonal shift in the above-mentioned inverse texture hypothesis.
Soil nutrients
Plants depend upon a range of nutrients to perform functions such as water uptake, stomatal
regulation, seed production etc. In nutrient-poor environments, plants may develop strategies
to better cope with a limited supply of nutrients, or to use available nutrients more efficiently
(da Silva et al. 2008). Effects of soil nutrients are often analyzed in relation to climatic
factors. Among-site variation in nutrient availability has been shown to affect flowering
phenology of plant populations (Black 1957; Dahlgren 2007). Investigating the effects of
environmental heterogeneity on flowering phenology in Actaea spicata, Dahlgren et al.
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(2007) found that within populations, there was a variation in flowering time related to
changes in microenvironment; small individuals on steep, south-facing slopes and on soils
richer in potassium emerged earlier and flowered earlier. Among plots, however, flowering
time was chiefly dependent on soil temperature, slope, and July canopy cover.
When studying soil type and local adaptation, greenhouse experiments are sometimes used to
control for surrounding environmental factors. One such experiment was carried out by
Abdala-Roberts & Marquis (2007), who tested whether soil source affected reproduction in C.
fasciculata, and also whether there was any local adaptation to soil abiotic conditions in the
populations studied. In the greenhouse, plants from three different sites were grown on the
home soil of all three sites. The results showed that soil from one site significantly increased
flower production in all populations, compared to soils from the other sites. This soil had the
highest percentage of organic matter and showed the highest concentrations of K, Ca, Mg and
nitrates, as well as the highest pH. However, plants grown on their native soil did not
outperform nonnatives, a result which suggests a plastic response to soil quality rather than
local adaptation.
Soil depth
As mentioned above, soil water content is strongly related to soil texture. Another factor
affecting soil water content is soil depth, which may influence soil water holding capacity and
thereby affect reproduction, growth and survival among plant populations (Toräng et al.
2007). In a three-year study on flowering and fruit set in relation to environmental factors in
Vincetoxicum hirundinaria, Ågren et al. (2008) monitored 39 populations of different size and
habitat quality. Here, fruit and flower production were expected to be positively related to soil
depth, particularly in dry summers. Their hypothesis was confirmed; Flower production was
positively related to sun exposure and soil depth, and fruit set was indirectly affected by those
variables through increase in flower number.
In another field study, Kephart & Paladino (1997) aimed at identifying environmental features
of two grassland microhabitats that may influence the population biology of Silene douglasii.
Comparing rocky and grassy growth sites, they found both temporal and spatial variation in
population growth rate. Most abiotic variables showed no significant difference between
habitats or varied more seasonally within a habitat than between grassy and rocky areas.
However, juvenile recruitment and adult survivorship were highest in open, rocky sites with
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low vegetation. From these findings, it was concluded that light might be a limiting factor in
deep soil areas with more vegetation, leading to life history differentiation in S. douglasii. In
this case, population growth rate was indirectly affected by soil depth, in terms of increased
vegetation density.
Climatic variation
Climatic variation has received much attention recently, much because of the issue of global
warming. During the past few decades, rapid changes in flowering time in response to
temperature changes have been reported. According to Fitter & Fitter (2002), there has been a
major shift in first flowering date in British plant species since the 1980’s, largely due to
increased temperature. In Campanula americanum, fall germinating seeds grow as annuals
and spring-germinating seeds are biennials (Baskin & Baskin 1984). In this species, selection
for earlier flowering by a warmer climate could result in correlated responses that alter the
species life history schedule (Burgess et al. 2007). Because whole community alterations
caused by global changes must begin with alterations of the population dynamics of the
component species, knowledge of the demographic response of plant species to global
changes is important to make predictions about future ecosystem function (Williams et al.
2007).
Drought
Not surprisingly, water availability plays an important role when examining adaptive
responses of plant populations to climatic variation. The effect of soil properties on local
adaptation in local and foreign populations of Taraxacum officinale was investigated in a
common-garden experiment performed by Quiroz et al. (2009). The aim of the study was to
investigate whether T. officinale populations of native and introduced origin were similarly
affected by environmental conditions. Plants from native (Alpine) and introduced (Andean)
populations were exposed to a drought experiment. With drought, individuals from both
origins showed phenotypic plasticity in the root:shoot ratio, increasing allocation to
belowground biomass. However, this plasticity was more pronounced among native
individuals. Furthermore, unlike the Alpine plants, plants from the Andean populations still
produced flowers when exposed to drought. Quiroz interprets this as an adaptation to the
considerably dryer growing conditions in central Chile, where higher levels of drought
tolerance are crucial to successful establishment.
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Clinal variation
Many studies on local adaptation are made along clinal geographical gradients, either as
reciprocal transplantations or in common-garden experiments. In one such study on Lythrum
salicaria along a clinal gradient in Sweden, Olsson & Ågren (2002) found different responses
in phenological and morphological traits across the country. Using a common-garden
experiment, they were able to show that characters such as phenology of growth and
flowering, allocation to winter buds and length of the juvenile period were correlated with
latitude of origin, whereas flower morphology displayed a more mosaic pattern of variation.
There was also a variation in growth pattern, with northern populations being taller early in
the season, probably as a consequence of the shorter growing season. However, these plants
were outgrown by plants from the southern populations at the end of the season.
A replant – transplant study on a larger geographical scale was performed by Joshi et al.
(2001). Here, individuals of three common plant species (Trifolium pratense, Dactylis
glomerata and Plantago lanceolata) were transplanted to eight field sites across Europe and
monitored for two years. Apart from testing for local adaptation, they also tested whether
selection against foreign strains increased with geographical distance. In T. pratense, local
adaptation was found in terms of reproduction (inflorescence diameter). In addition to higher
reproductive performance, local strains of P. lanceolata and D. glomerata also showed
enhanced vegetative growth (leaf length). Overall, selection was strongest against northern
strains of all three species. However, climatic distance only explained 18% of the variance of
distance in the analysis of selection indices, indicating that other local environmental factors
may also have exerted strong selection pressures.
Biotic interactions
To a great extent, selection on demography and life history of plant populations is the result of
biotic interactions. Biotic environments evolve, and may coevolve with plant species
(Kawecki & Ebert 2004; Agrawal et al. 2006). The outcome of biotic interactions may be
mutualistic, commensalistic or parasitic, sometimes altering between different modes of
interaction, and has been described as the raw material for the evolution of biotic communities
(Thompson 1988).
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Pollinators
There are several examples of mutualistic interactions between plants and their biotic
environments. However, the most common and diverse mutualisms - at least above ground –
occur between plants and their pollinators. These interactions may largely influence
population persistence, and Hegland et al. (2009) suggest two ways in which plant-pollinator
interactions can be disrupted: Through temporal or spatial mismatch among plants and
pollinators altering the availability of mutualistic partners, which may result in rapid evolution
in plant pollination and reproductive traits and in foraging and phenological traits in
pollinators. Paige and Whitham (1987) studied the effects of pollinator abundance on lifehistory traits in Ipomopsis aggregata at different altitudes in Fern Mountain, Arizona.
Experimental pollinator exclusions were performed, showing that at high altitudes, where
pollinator abundance was fluctuating, I. aggregata could shift from its normal semelparous
mode of reproduction to iteroparous reproduction in response to low levels of fruit set and
pollinator abundance. In response to low fruit set, individual plants were able to reallocate
resources to rosette formation, thereby shifting from semelparity to iteroparity. At lower
altitudes, however, where pollinator densities normally showed little variation, only one out of
37 individuals altered its reproductive pattern in response to experimental pollinator
exclusion, suggesting that flexibility in life cycle pattern may represent a local adaptation.
Surrounding vegetation
Apart from being affected by abiotic conditions and animal interactions, Plants are also
constantly affected by the surrounding plant community, and the fitness consequences of plant
- plant interactions can be positive or negative (Tuomi et al. 1999). Bischoff et al. (2006)
studied the effect of competition within the local plant community on local adaptation of
Holcus lanatus, Lotus corniculatus and Plantago lanceolata. Bischoff compared the
performance of plants of different origin sown in weeded monocultures with the performance
when sown in a local grassland community context. Local adaptation was evident in terms of
seedling emergence, reproduction and survival rates of P. lanceolata, and reproductive traits
such as panicle and seed number in H. lanatus. For P. lanceolata, the home vs. foreign
contrast of most traits was stronger in the presence of the local plant community. For H.
lanatus, on the other hand, this contrast was more pronounced when the plants were grown in
a weeded monoculture. In L. corniculatus, no evidence of any home site advantage was
found. According to Bischoff, these results show that local adaptation may be affected by
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competition with the local plant community, as a result of community-specific abiotic
conditions to which species are adapted.
Neighboring plants may also exert chemically mediated selection pressures on plant
populations. Grondahl & Ehlers (2008) performed reciprocal transplantations to investigate
local adaptation to neighboring plants with aromatic compounds. Plants from environments
with different terpenes were transplanted to soil containing these different terpenes and found
that the transplanted plants performed better on soil containing the home-terpene, in terms of
seed germination and root biomass. For Achillea millefolium, however, the aboveground
biomass was lower for plants growing on home soil, which was interpreted as compensation
for the increased root biomass. The results also indicated that there was a trade off between
increased root biomass and reproductive investment. For both P. lanceolata and A.
millefolium, reproductive investment was larger on control soil.
Discussion
The most common designs for studying local adaptation in plant populations are observational
studies, common garden experiments and reciprocal transplant experiments. From
observational studies, local differences have been reported in features such as rate of survival,
germination of seedlings, growth rate and flowering phenology. However, there is no
knowing whether these findings represent local adaptation of phenotypic plasticity. To rule
out phenotypic plasticity, many studies have been performed using common garden
experiments. Here, variation in vegetative growth, reproduction, survival, seedling
germination and phenology has been reported as local adaptations in plant populations.
However, using common garden experiments may still not answer the question whether the
observed genotypic variation is actually the result of selection pressure imposed by the
environment or whether it is merely the result of factors such as isolation or genetic drift. I
found two examples of reciprocal transplantation studies on local adaptation in plant life
history traits. In one of these studies, where local adaptation to climatic factors was studied on
a European scale, local adaptation was mainly expressed in reproductive features, although to
some extent also in vegetative growth. In the other, which focused on the effects of
neighboring plants with aromatic compounds, local plants performed better in terms of seed
germination and below-ground biomass. There were also examples where common garden
studies were combined with experimental manipulations. Using this type of design, it is
possible to expose plants of different origins to simulated field conditions of varying quality,
13
while still working in a controlled environment. These experiments may provide more valid
information about local adaptation than regular common garden experiments. Judging from
these studies, it would seem that observational studies should be combined with, or followed
by, experimental studies, when studying local adaptation in plant populations.
The environmental factors discussed in this paper affected different aspects of life history of
the studied populations. On small spatial scales, under similar climatic and geographic
conditions, plant population responses were expressed in terms of flowering phenology,
flower production and seedling recruitment. On larger spatial scales, where the plant
populations studied were often exposed to different latitudinal or altitudinal conditions,
evidence of local adaptation was mainly found in traits such as phenology of growth and
flowering, growth pattern and reproductive effort. Regarding soil properties, most of the
studies were observational, which makes it difficult to draw conclusions about local
adaptation. Moreover, soil properties seemed to act on rather local scales, and were often
closely linked to other environmental factors, such as vegetation structure and humidity.
However, whether adaptive or plastic, the traits affected by heterogeneous soil conditions
were vegetative, demographic and phenological. Responses to climatic variation included
variation in reproductive characters and flowering phenology. In addition, differences in
drought-resistance between populations of different origin were found, indicating local
adaptation. Finally, in the studies on adaptation of plants to their biotic environment, effects
on reproductive pattern, demography and vegetative growth were observed.
Many articles on local adaptation highlight the difficulty to distinguish possible driving forces
behind the observed patterns of differentiation (Kephart & Paladino 1997; Crémieux et al.
2008). One reason for this is that many environmental factors often act together on the
demography and life history of plant populations, such as soil texture and humidity or soil
depth combined with sun exposure and vegetation density. Due to the unstable nature of the
biotic environment itself, plants tend to respond to biotic selective agents in a mosaic pattern
and it is often difficult to disentangle selection pressures exerted by single agents. Plant
population size has frequently been reported to affect pollinator abundance and activity.
Moreover, plants themselves may exert considerable selective pressure on neighboring plant
species. Furthermore, the selective impact of certain environmental conditions may vary
between years or even between seasons; different combinations of soil characteristics and
climatic condition may render different selective pressures, governed by factors such as soil
14
water retaining capacity. Despite these difficulties, though, the effort of conducting research
on environmentally induced life history differentiation in plant populations is still worthwhile,
since it provides valuable information about evolutionary mechanisms, and demographic
responses to changing environmental conditions. Furthermore, in terms of conservation,
increased knowledge of life history responses to environmental heterogeneity on different
temporal and spatial scales is of great importance. By combining observational and
experimental methods for detecting local adaptation, a greater understanding of the processes
governing life history responses to environmental variation may be obtained.
Acknowledgements
Thanks to my supervisor Johan Ehrlén for reading and providing comments on this paper.
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A., Huss-Danell, K., Jumpponen, A., Minns, A., Mulder, C. P. H., Pereira, J. S., Prinz, A.,
Scherer-Lorenzen, M., Siamantziouras, A. S. D., Terry, A. C., Troumbis, A. Y. & Lawton,
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Serien Plants & Ecology (ISSN 1651-9248) har tidigare haft namnen "Meddelanden från
Växtekologiska avdelningen, Botaniska institutionen, Stockholms Universitet" nummer
1978:1 – 1993:1 samt "Växtekologi". (ISSN 1400-9501) nummer 1994:1 – 2003:3.
Följande publikationer ingår i utgivningen:
1978:1
1978:2
1978:3
1978:4:
1978:5
1979:1
1979:2
1979:3
1979:4
1979:5
1980:1
1980:2
1980:3
1981:1
1983:1
1984:1
1986:1
1986:2
1987:1
1987:2
1988:1
1988:2
1988:3
1989:1
Liljelund, Lars-Erik: Kompendium i matematik för ekologer.
Carlsson, Lars: Vegetationen på Littejåkkadeltat vid Sitasjaure, Lule Lappmark.
Tapper, Per-Göran: Den maritima lövskogen i Stockholms skärgård.
Forsse, Erik: Vegetationskartans användbarhet vid detaljplanering av
fritidsbebyggelse.
Bråvander, Lars-Gunnar och Engelmark, Thorbjörn: Botaniska studier vid
Porjusselets och St. Lulevattens stränder i samband med regleringen 1974.
Engström, Peter: Tillväxt, sulfatupptag och omsättning av cellmaterial hos
pelagiska saltvattensbakterier.
Eriksson, Sonja: Vegetationsutvecklingen i Husby-Långhundra de senaste
tvåhundra åren.
Bråvander, Lars-Gunnar: Vegetation och flora i övre Teusadalen och vid Autaoch Sitjasjaure; Norra Lule Lappmark. En översiktlig inventering med anledning av
områdets exploatering för vattenkraftsändamål i Ritsemprojektet.
Liljelund, Lars-Erik, Emanuelsson, Urban, Florgård, C. och Hofman-Bang,
Vilhelm: Kunskapsöversikt och forskningsbehov rörande mekanisk påverkan på
mark och vegetation.
Reinhard, Ylva: Avloppsinfiltration - ett försök till konsekvensbeskrivning.
Telenius, Anders och Torstensson, Peter: Populationsstudie på Spergularia marina
och Spergularia media. I Frödimorfism och reproduktion.
Hilding, Tuija: Populationsstudier på Spergularia marina och Spergularia media.
II Resursallokering och mortalitet.
Eriksson, Ove: Reproduktion och vegetativ spridning hos Potentilla anserina L.
Eriksson, Torsten: Aspekter på färgvariation hos Dactylorhiza sambucina.
Blom, Göran: Undersökningar av lertäkter i Färentuna, Ekerö kommun.
Jerling, Ingemar: Kalkning som motåtgärd till försurningen och dess effekter på
blåbär, Vaccinium myrtillus.
Svanberg, Kerstin: En studie av grusbräckans (Saxifraga tridactylites) demografi.
Nyberg, Hans: Förändringar i träd- och buskskiktets sammansättning i
ädellövskogen på Tullgarnsnäset 1960-1983.
Edenholm, Krister: Undersökningar av vegetationspåverkan av vildsvinsbök i
Tullgarnsområdet.
Nilsson, Thomas: Variation i fröstorlek och tillväxthastighet inom släktet Veronica.
Ehrlén, Johan: Fröproduktion hos vårärt (Lathyrus vernus L.). - Begränsningar och
reglering.
Dinnétz, Patrik: Local variation in degree of gynodioecy and protogyny in Plantago
maritima.
Blom, Göran och Wincent, Helena: Effekter of kalkning på ängsvegetation.
Eriksson, Pia: Täthetsreglering i Littoralvegetation.
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1989:2 Kalvas, Arja: Jämförande studier av Fucus-populationer från Östersjön och
västkusten.
1990:1 Kiviniemi, Katariina: Groddplantsetablering och spridning hos smultron, Fragaria
vesca.
1990:2 Idestam-Almquist, Jerker: Transplantationsförsök med Borstnate.
1992:1 Malm, Torleif: Allokemisk påverkan från mucus hos åtta bruna makroalger på
epifytiska alger.
1992:2 Pontis, Cristina: Om groddknoppar och tandrötter. Funderingar kring en klonal
växt: Dentaria bulbifera.
1992:3 Agartz, Susanne: Optimal utkorsning hos Primula farinosa.
1992:4 Berglund, Anita: Ekologiska effekter av en parasitsvamp - Uromyces lineolatus på
Glaux maritima (Strandkrypa).
1992:5 Ehn, Maria: Distribution and tetrasporophytes in populations of Chondrus crispus
Stackhouse (Gigartinaceae, Rhodophyta) on the west coast of Sweden.
1992:6 Peterson, Torbjörn: Mollusc herbivory.
1993:1 Klásterská-Hedenberg, Martina: The influence of pH, N:P ratio and zooplankton
on the phytoplanctic composition in hypertrophic ponds in the Trebon-region, Czech
Republic.
1994:1 Fröborg, Heléne: Pollination and seed set in Vaccinium and Andromeda.
1994:2 Eriksson, Åsa: Makrofossilanalys av förekomst och populationsdynamik hos Najas
flexilis i Sörmland.
1994:3 Klee, Irene: Effekter av kvävetillförsel på 6 vanliga arter i gran- och tallskog.
1995:1 Holm, Martin: Beståndshistorik - vad 492 träd på Fagerön i Uppland kan berätta.
1995:2 Löfgren, Anders: Distribution patterns and population structure of an economically
important Amazon palm, Jessenia bataua (Mart.) Burret ssp. bataua in Bolivia.
1995:3 Norberg, Ylva: Morphological variation in the reduced, free floating Fucus
vesiculosus, in the Baltic Proper.
1995:4 Hylander, Kristoffer & Hylander, Eva: Mount Zuquala - an upland forest of
Ethiopia. Floristic inventory and analysis of the state of conservation.
1996:1 Eriksson, Åsa: Plant species composition and diversity in semi-natural grasslands with special emphasis on effects of mycorrhiza.
1996:2 Kalvas, Arja: Morphological variation and reproduction in Fucus vesiculosus L.
populations.
1996:3 Andersson, Regina: Fågelspridda frukter kemiska och morfologiska egenskaper i
relation till fåglarnas val av frukter.
1996:4 Lindgren, Åsa: Restpopulationer, nykolonisation och diversitet hos växter i
naturbetesmarker i sörmländsk skogsbygd.
1996:5 Kiviniemi, Katariina: The ecological and evolutionary significance of the early life
cycle stages in plants, with special emphasis on seed dispersal.
1996:7 Franzén, Daniel: Fältskiktsförändringar i ädellövskog på Fagerön, Uppland,
beroende på igenväxning av gran och skogsavverkning.
1997:1 Wicksell, Maria: Flowering synchronization in the Ericaceae and the Empetraceae.
1997:2 Bolmgren, Kjell: A study of asynchrony in phenology - with a little help from
Frangula alnus.
1997:3 Kiviniemi, Katariina: A study of seed dispersal and recruitment of plants in a
fragmented habitat.
1997:4 Jakobsson, Anna: Fecundity and abundance - a comparative study of grassland
species.
1997:5 Löfgren, Per: Population dynamics and the influence of disturbance in the Carline
Thistle, Carlina vulgaris.
19
1998:1 Mattsson, Birgitta: The stress concept, exemplified by low salinity and other stress
factors in aquatic systems.
1998:2 Forsslund, Annika & Koffman, Anna: Species diversity of lichens on decaying
wood - A comparison between old-growth and managed forest.
1998:3 Eriksson, Åsa: Recruitment processes, site history and abundance patterns of plants
in semi-natural grasslands.
1998:4 Fröborg, Heléne: Biotic interactions in the recruitment phase of forest field layer
plants.
1998:5 Löfgren, Anders: Spatial and temporal structure of genetic variation in plants.
1998:6 Holmén Bränn, Kristina: Limitations of recruitment in Trifolium repens.
1999:1 Mattsson, Birgitta: Salinity effects on different life cycle stages in Baltic and North
Sea Fucus vesiculosus L.
1999:2 Johannessen, Åse: Factors influencing vascular epiphyte composition in a lower
montane rain forest in Ecuador. An inventory with aspects of altitudinal distribution,
moisture, dispersal and pollination.
1999:3 Fröborg, Heléne: Seedling recruitment in forest field layer plants: seed production,
herbivory and local species dynamics.
1999:4 Franzén, Daniel: Processes determining plant species richness at different scales examplified by grassland studies.
1999:5 Malm, Torleif: Factors regulating distribution patterns of fucoid seaweeds. A
comparison between marine tidal and brackish atidal environments.
1999:6 Iversen, Therese: Flowering dynamics of the tropical tree Jacquinia nervosa.
1999:7 Isæus, Martin: Structuring factors for Fucus vesiculosus L. in Stockholm south
archipelago - a GIS application.
1999:8 Lannek, Joakim: Förändringar i vegetation och flora på öar i Norrtälje skärgård.
2000:1 Jakobsson, Anna: Explaining differences in geographic range size, with focus on
dispersal and speciation.
2000:2 Jakobsson, Anna: Comparative studies of colonisation ability and abundance in
semi-natural grassland and deciduous forest.
2000:3 Franzén, Daniel: Aspects of pattern, process and function of species richness in
Swedish seminatural grasslands.
2000:4 Öster, Mathias: The effects of habitat fragmentation on reproduction and population
structure in Ranunculus bulbosus.
2001:1 Lindborg, Regina: Projecting extinction risks in plants in a conservation context.
2001:2 Lindgren, Åsa: Herbivory effects at different levels of plant organisation; the
individual and the community.
2001:3 Lindborg, Regina: Forecasting the fate of plant species exposed to land use change.
2001:4 Bertilsson, Maria: Effects of habitat fragmentation on fitness components.
2001:5 Ryberg, Britta: Sustainability aspects on Oleoresin extraction from Dipterocarpus
alatus.
2001:6 Dahlgren, Stefan: Undersökning av fem havsvikar i Bergkvara skärgård, östra
egentliga Östersjön.
2001:7 Moen, Jon; Angerbjörn, Anders; Dinnetz, Patrik & Eriksson Ove: Biodiversitet i
fjällen ovan trädgränsen: Bakgrund och kunskapsläge.
2001:8 Vanhoenacker, Didrik: To be short or long. Floral and inflorescence traits of Bird`s
eye primrose Primula farinose, and interactions with pollinators and a seed predator.
2001:9 Wikström, Sofia: Plant invasions: are they possible to predict?
2001:10 von Zeipel, Hugo: Metapopulations and plant fitness in a titrophic system – seed
predation and population structure in Actaea spicata L. vary with population size.
20
2001:11 Forsén, Britt: Survival of Hordelymus europaéus and Bromus benekenii in a
deciduous forest under influence of forest management.
2001:12 Hedin, Elisabeth: Bedömningsgrunder för restaurering av lövängsrester i Norrtälje
kommun.
2002:1 Dahlgren, Stefan & Kautsky, Lena: Distribution and recent changes in benthic
macrovegetation in the Baltic Sea basins. – A literature review.
2002:2 Wikström, Sofia: Invasion history of Fucus evanescens C. Ag. in the Baltic Sea
region and effects on the native biota.
2002:3 Janson, Emma: The effect of fragment size and isolation on the abundance of Viola
tricolor in semi-natural grasslands.
2002:4 Bertilsson, Maria: Population persistance and individual fitness in Vicia pisiformis:
the effects of habitat quality, population size and isolation.
2002:5 Hedman, Irja: Hävdhistorik och artrikedom av kärlväxter i ängs- och hagmarker på
Singö, Fogdö och norra Väddö.
2002:6 Karlsson, Ann: Analys av florans förändring under de senaste hundra åren, ett
successionsförlopp i Norrtälje kommuns skärgård.
2002:7 Isæus, Martin: Factors affecting the large and small scale distribution of fucoids in
the Baltic Sea.
2003:1 Anagrius, Malin: Plant distribution patterns in an urban environment, Södermalm,
Stockholm.
2003:2 Persson, Christin: Artantal och abundans av lavar på askstammar – jämförelse
mellan betade och igenvuxna lövängsrester.
2003:3 Isæus, Martin: Wave impact on macroalgal communities.
2003:4 Jansson-Ask, Kristina: Betydelsen av pollen, resurser och ljustillgång för
reproduktiv framgång hos Storrams, Polygonatum multiflorum.
2003:5 Sundblad, Göran: Using GIS to simulate and examine effects of wave exposure on
submerged macrophyte vegetation.
2004:1 Strindell, Magnus: Abundansförändringar hos kärlväxter i ädellövskog – en
jämförelse av skötselåtgärder.
2004:2 Dahlgren, Johan P: Are metapopulation dynamics important for aquatic plants?
2004:3 Wahlstrand, Anna: Predicting the occurrence of Zostera marina in bays in the
Stockholm archipelago,northern Baltic proper.
2004:4 Råberg, Sonja: Competition from filamentous algae on Fucus vesiculosus –
negative effects and the implications on biodiversity of associated flora and fauna.
2004:5 Smaaland, John: Effects of phosphorous load by water run-off on submersed plant
communities in shallow bays in the Stockholm archipelago.
2004:6 Ramula Satu: Covariation among life history traits: implications for plant
population dynamics.
2004:7 Ramula, Satu: Population viability analysis for plants: Optimizing work effort and
the precision of estimates.
2004:8 Niklasson, Camilla: Effects of nutrient content and polybrominated phenols on the
reproduction of Idotea baltica and Gammarus ssp.
2004:9 Lönnberg, Karin: Flowering phenology and distribution in fleshy fruited plants.
2004:10 Almlöf, Anette: Miljöfaktorers inverkan på bladmossor i Fagersjöskogen, Farsta,
Stockholm.
2005:1 Hult, Anna: Factors affecting plant species composition on shores - A study made in
the Stockholm archipelago, Sweden.
2005:2 Vanhoenacker, Didrik: The evolutionary pollination ecology of Primula farinosa.
2005:3 von Zeipel, Hugo: The plant-animal interactions of Actea spicata in relation to
spatial context.
21
2005:4 Arvanitis, Leena T.: Butterfly seed predation.
2005:5 Öster, Mathias: Landscape effects on plant species diversity – a case study of
Antennaria dioica.
2005:6 Boalt, Elin: Ecosystem effects of large grazing herbivores: the role of nitrogen.
2005:7 Ohlson, Helena: The influence of landscape history, connectivity and area on
species diversity in semi-natural grasslands.
2005:8 Schmalholz, Martin: Patterns of variation in abundance and fecundity in the
endangered grassland annual Euphrasia rostkovia ssp. Fennica.
2005:9 Knutsson, Linda: Do ants select for larger seeds in Melampyrum nemorosum?
2006:1 Forslund, Helena: A comparison of resistance to herbivory between one exotic and
one native population of the brown alga Fucus evanescens.
2006:2 Nordqvist, Johanna: Effects of Ceratophyllum demersum L. on lake phytoplankton
composition.
2006:3 Lönnberg, Karin: Recruitment patterns, community assembly, and the evolution of
seed size.
2006:4 Mellbrand, Kajsa: Food webs across the waterline - Effects of marine subsidies on
coastal predators and ecosystems.
2006:5 Enskog, Maria: Effects of eutrophication and marine subsidies on terrestrial
invertebrates and plants.
2006:6 Dahlgren, Johan: Responses of forest herbs to the environment.
2006:7 Aggemyr, Elsa: The influence of landscape, field size and shape on plant species
diversity in grazed former arable fields.
2006:8 Hedlund, Kristina: Flodkräftor (Astacus astacus) i Bornsjön, en omnivors påverkan
på växter och snäckor.
2007:1 Eriksson, Ove: Naturbetesmarkernas växter- ekologi, artrikedom och
bevarandebiologi.
2007:2 Schmalholz, Martin: The occurrence and ecological role of refugia at different
spatial scales in a dynamic world.
2007:3 Vikström, Lina: Effects of local and regional variables on the flora in the former
semi-natural grasslands on Wäsby Golf club’s course.
2007:4 Hansen, Joakim: The role of submersed angiosperms and charophytes for aquatic
fauna communities.
2007:5 Johansson, Lena: Population dynamics of Gentianella campestris, effects of
grassland management, soil conditions and the history of the landscape
2007:6 von Euler, Tove: Sex related colour polymorphism in Antennaria dioica.
2007:7 Mellbrand, Kajsa: Bechcombers, landlubbers and able seemen: Effects of marine
subsidies on the roles of arthropod predators in coastal food webs.
2007:8 Hansen, Joakim: Distribution patterns of macroinvertebrates in vegetated, shallow,
soft-bottom bays of the Baltic Sea.
2007:9 Axemar, Hanna: An experimental study of plant habitat choices by
macroinvertebrates in brackish soft-bottom bays.
2007:10 Johnson, Samuel: The response of bryophytes to wildfire- to what extent do they
survive in-situ?
2007:11 Kolb, Gundula: The effects of cormorants on population dynamics and food web
structure on their nesting islands.
2007:12 Honkakangas, Jessica: Spring succession on shallow rocky shores in northern
Baltic proper.
2008:1 Gunnarsson, Karl: Påverkas Fucus radicans utbredning av Idotea baltica?
2008:2 Fjäder, Mathilda: Anlagda våtmarker i odlingslandskap- Hur påverkas
kärlväxternas diversitet?
22
2008:3 Schmalholz, Martin: Succession in boreal bryophyte communities – the role of
microtopography and post-harvest bottlenecks.
2008:4 Jokinen, Kirsi: Recolonization patterns of boreal forest vegetation following a
severe flash flood.
2008:5 Sagerman, Josefin: Effects of macrophyte morphology on the invertebrate fauna in
the Baltic Sea.
2009:1 Andersson, Petter: Quantitative aspects of plant-insect interaction in fragmented
landscapes – the role of insect search behaviour.
2009:2 Kolb, Gundula: The effects of cormorants on the plant-arthropod food web on their
nesting islands.
2009:3 Johansson, Veronika: Functional traits and remnant populations in abandoned
semi-natural grasslands.
2009: 4 König, Malin: Phenotypic selection on flowering phenology and herbivory in
Cardamine amara.
2009:5 Forslund, Helena: Grazing and the geographical range of seaweeds –
The introduced Fucus evanescens and the newly described Fucus radicans.
23