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DOTTORATO IN SCIENZE AMBIENTALI
Genetica e conservazione della
biodiversità
Ettore Randi
Laboratorio di Genetica
ISPRA, sede di Ozzano Emilia (BO)
Università di Bologna
[email protected]
giovedì 1 ottobre ore 14:30-17:30
1 genetica, genomica e conservazione della biodiversità
2 conseguenze genetiche della frammentazione
venerdì 2 ottobre ore 14:30-17:30
3 ibridazione naturale e antropogenica
4 monitoraggio genetico delle popolazioni naturali
Corso di Dottorato in Scienze Ambientali – Università degli Studi di Milano
Coordinatore: Prof. Nicola Saino; [email protected]
website: http://www.environsci.unimi.it/
Genetica, genomica e conservazione della
biodiversità
Ettore Randi
Laboratorio di Genetica
ISPRA, sede di Ozzano Emilia (BO)
[email protected]
Images dowloaded for non-profit educational presentation use only
Transition from conservation GENETICS
to conservation GENOMICS
Next-generation (massive parallel) sequencing: … not simply more markers
Conservation Biology
1980
1986
Conservation Genetics
“Conservation genetics: the theory and practice of genetics in the
preservation of species as dynamic entities capable of evolving to
cope with environmental change to minimize their risk of extinction”
Conservation Genetics/Genomics
Genetic diversity is the driver and the
consequence of biological evolution
protection & conservation of biodiversity
protection & conservation of the processes & products of evolution
The Convention on Biological Diversity CDB
Rio de Janeiro 1992
Biodiversity
Biodiversity = the diversity of life
Genetic diversity
Diversity of species and populations
Diversity of communities, ecosystems and landscapes
CBD: three layers of biodiversity
Genes
Species
Ecosystems
Anthropogenic rapid evolution?
Rapid evolution
Conservation genetics: the theory and practice of genetics in the preservation of species as dynamic
entities capable of evolving to cope with environmental change to minimize their risk of extinction
In the face of environmental change, species must either respond to the
selective pressures imposed by the environment or ultimately be lost to
extinction.
Implicit in most conservationist thinking is that human disturbance occurs at
rates so rapid that the glacially slow process of adaptation through natural
selection cannot occur, and therefore evolutionary change is of minor
importance in our quest to preserve biodiversity.
Yet there is growing evidence that evolutionary shifts are sometimes very
rapid and are probably changing many of the species we are trying to
protect.
Industrial melanism in the peppered moth
Biston betularia
Industrial melanism in the peppered moth
Biston betularia
The cane toad (Bufo marinus) invasion
Rapid described evolution in Alien invasive species (AIS)
Populations adapting to global climate changes (GCC)
Hybridizing populations
travel up to 1.8 km per night
2 kg
Phillips Nature 2006
The cane toad invasion in Australia
Introduced to Queensland in 1935 to control insect pests in sugar-cane
fields, cane toads have since expanded their range to encompass more
than a million square kilometres of tropical and subtropical Australia
The future of cane toad invasion
Leg length and expansions in toads
Predictions:
1. Longer-legged toads should be disproportionately common among the first wave
of arrivals at any site.
Longer-legged toads were the first to pass through, followed by shorter-legged
conspecifics (order of arrival versus relative leg length).
Leg length and expansions in toads
Predictions:
2. Toads at the invasion front should be longer-legged than toads from older
populations.
Relative leg length is greatest in new arrivals and then declines over a 60-year period.
Leg length and expansions in toads
Predictions:
3. The rate of progress of the toad invasion front should increase through time.
Toads expanded their range by about 10 km a year during the 1940s to 1960s, but are
now invading new areas at a rate of over 50 km a year.
Leg length and expansions in toads
Predictions:
4. Toads with longer legs should move faster
Toads with longer legs move faster than toads with shorter legs over 3-days periods
Eurasian sparrow Passer spp. introduced in N. America
Anthropogenic introductions of the Eurasian Tree Sparrow (Passer montanus) in North America,
are important to the evaluation of microevolutionary processes. P. montanus was established in
North America in 1870 when a bird dealer released 12 pairs of West German origin in Lafayette
Park, St. Louis, Missouri.
The smaller body size of North American P. montanus is thought to result either from interspecific
interactions and/or flight habits different from their ancestral counterparts. Significant differences
in bill morphology are found between German and North American P. montanus, which we believe
reflect differences in diet. The North American population shows no significant decrease in intrinsic
morphometric variation corresponding to the decrease in genetic variation demonstrated in
comparison to German birds.
Common mynas Acridotheres tristis introduced in
New Zealand
Populations of Common Mynas (Acridotheres tristis), although restricted
to the northern two-thirds of the North Island, have also differentiated
much more than have chaffinches over the whole of New Zealand
European starling Sturnus vulgaris introduced in New
Zealand
Contemporaneous populations of House Sparrows (Passer domesticus) and
European Starlings (Sturnus vulgaris), sampled over the same geographic range as
chaffinches, have clearly differentiated morphometrically much more than the latter
Climate change drives microevolution in tawny owls
(Strix aluco)
To ensure long-term persistence, organisms must adapt to climate change =
evolutionary response to a quantified selection pressure driven by climate change.
Pheomelanin-based plumage colouration in tawny owls is a highly heritable trait.
Strong viability selection against the brown morph occurs only under snow-rich
winters. As winter conditions became milder in the last decades, selection against the
brown morph diminished.
The frequency of brown morphs increased rapidly in our study population during the
last 28 years and nationwide during the last 48 years. Recent climate change alters
natural selection in a wild population leading to a microevolutionary response, which
demonstrates the ability of wild populations to evolve in response to climate change.
(Karell Nature 2011)
Climate change drives microevolution in tawny owls
Climate change drives microevolution in tawny owls
Decline of over-exploited fish stocks
Decling growth rates & early maturation in overexploited fish stocks
Anthropogenic hybridization
Musiani Molecular Ecology 2007
Contemporary microevolution
Introduced species , AIMs, island populations, over-exploited stocks … … are interesting
systems for the study of contemporary micro evolution in new environments:
i)
to determine how genetic diversity and genetic differentiation of introduced
populations varies with range expansion
ii) to determine how genetic diversity and differentiation compares to ancestral
populations
iii) to determine whether selection or genetic drift has been more influential on
phenotypic divergence.
Rapid evolution /adaptation
Contemporary micro-evolution: many organisms can undergo adaptive
phenotypic evolution over just a few generations. Evolution can happen on
ecological timescales; cologically significant evolutionary change, occurring
over tens of generations or fewer.
Factors that influence evolution on ecological time-scales:
- phenotypic plasticity
- maternal effects
- epigenetics
- sexual selection
- gene flow
Consequences of rapid evolution on:
- population persistence (conservation genetics)
- speciation rats (biodiversity)
- community dynamics (ecology)
- ecosystem functions (ecosystem services)
The 11 major genetic issues in conservation biology
• population decline - fragmentation - isolation
• loss of genetic diversity - loss of adaptability
• inbreeding - inbreeding depression
• stochastic processes in small populations
• deleterious mutations
conservation of heterozigosity and fitness
• taxonomic uncertainties - ESUs
• management units - MUs
• molecular genetics and population biology
conservation of evolutionary lineages
• molecular genetics and forensics
• captive breeding - adaptation to captivity
• management of natural populations:
admixtures
hybridization
outbreeding depression
management of the genetic diversity
Extinctions: The sixth extinction
1.
2.
3.
4.
5.
population decline - fragmentation - isolation
loss of genetic diversity - loss of adaptability
inbreeding - inbreeding depression
stochastic processes in small populations
deleterious mutations
The sixth extinction
Human population growth and invasion
Extinction of the passenger pigeon Ectopistes migratorius
[There is ‘no single ‘magic’ population size that guarantees’ population persistence]
One flock in 1866 in southern Ontario was described as being 1.5 km wide and 500 km long, took 14
hours to pass, and held in excess of 3.5 billion birds (total N > 5 billions).
Some reduction in numbers occurred from habitat loss when European settlement led to
mass deforestation. Next, pigeon meat was commercialized as a cheap food for slaves and the poor
in the 19th century, resulting in hunting on a massive and mechanized scale. A slow decline
between about 1800 and 1870 was followed by a catastrophic decline between 1870 and
1890. Martha, the world's last passenger pigeon, died on September 1, 1914, at the Cincinnati Zoo.
EU bees extinction risks
The extinction vortex
The extinction vortex: Bottleneck
The extinction vortex: Genetic drift
WARREN KEELAN/THE INTERNATIONAL LANDSCAPE PHOTOGRAPHER OF THE YEAR 2015
The extinction vortex: Genetic drift
Consequences of genetic drift:
Variability lost by chance
The extinction vortex: Inbreeding
The consequences of inbreeding:
Inbreeding depression
The extinction vortex
Molecular markers in conservation genetics
DNA replication in vitro: the PCR
Gel electrophoresis
Acrylammide gel sequencing
Automated DNA sequencing
Capillary electrophoresis
Manual vs automated DNA sequencing
Genetic variability: SNPs
Next-generation sequencing
Parallel sequencing
Pyrosequencing
… the omics worlds…