DOTTORATO IN SCIENZE AMBIENTALI Genetica e conservazione della biodiversità
Ettore Randi
Laboratorio di Genetica ISPRA, sede di Ozzano Emilia (BO) Università di Bologna
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)
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 over- exploited 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. population decline - fragmentation - isolation 2. loss of genetic diversity - loss of adaptability 3. inbreeding - inbreeding depression 4. stochastic processes in small populations 5. 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…