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51 Cards in this Set
- Front
- Back
Definition of conservation genetics |
interdisciplinary science aiming to apply genetic methods to the conservation of biodiversity aims to preserve species as dynamic entities capable of coping with environmental change, and to minimize their extinction risks |
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Importance of genetic diversity |
fundamental level of biodiversity -> directly relevant to biodiversity conservation |
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Evolutionary importance of biodiversity |
genome potential to serve as starting point for the evolution of new genomes homogenisation |
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genome |
each genome represents cumulative adaptation to a given set of circumstances |
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potential |
each genome has potential to serve as starting point for the evolution of new genomes (modification by descent) |
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homogenisation |
or loss of genomes results in loss of potentially new evolutionary pathways to counter changing environments |
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SGD (standing genetic diversity) |
presence of more than one allele at a locus in a population |
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threespine stickleback (gasterosteus aculeatus) |
marine populations have 30-36 bony plates on body protect against puncture wounds from predators |
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Plates are associated with ____ gene Some aspects of this gene |
Eda has both low (L) and high (C) alleles evolved 1-2 million years ago marine populations low frequency of L allele (~1%) |
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CC gene = CL gene = LL gene = |
CC = lots of plates CL = half covered in plates LL = no plates |
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SGD (standing genetic diversity) |
marine ancestors recently invaded deglaciated freshwater have become low plated |
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In freshwater |
plates are bad - they cost minerals and energy |
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fish with reduced armor |
grow faster, are less prone to predation by insects, breed earlier and are more fecund |
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Barrett et al. sampled marine populations and used ... |
heterozygotes to seed 4 freshwater populations sub-sampled (at random) the F1 offspring over 1 year; F2 over 2 years |
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L allele frequency ... |
increased significantly in all 4 populations |
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genotypic frequencies changed significantly from .. |
the expected by hardy-weinberg equilibrium |
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Evolution occurred within just 2 generations making it... |
rapid evolution |
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this rapid evolution shows the importance of... |
SGD in rapid adaptability and evolutionary capability of populations |
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Experiment about sticklebacks shows in terms of temperature that... |
freshwater sticklebacks are able to tolerate much lower temperatures than marine sticklebacks this difference is heritable |
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Extinct species how many global extinction since 1600? |
more than 700 recorded |
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Standing genetic diversity is very important for... |
rapid evolution - may help prevent extinctions |
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how much of modern extinctions are caused by humans? |
99% |
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Importance of demography |
more than 700 recorded global extinctions since 1600 much higher extinction rates on insular systems (islands) |
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percentage of extinctions per group on islands |
mammals: 60 birds: 81 reptiles: 95 amphibians: 0 fish: 4 molluscs: 79 invertebrates: 49 flowering plants: 36 |
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small isolated populations |
human activities -> fragmentation into small, isolated populations -> extinction prone susceptible to environmental and demographic stochasticity genetic factors contribute to extinctions as well even when condition improve, genetic problems associated with small population size can linger |
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inbreeding |
mating between individuals carrying alleles identical increased homozygosity and thus likelihood of exposing deleterious alleles |
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deleterious alleles are often... |
hidden in heterozygotic individuals by dominant alleles |
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high levels of inbreeding can result in |
inbreeding depression |
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Inbreeding depression |
reduction in the fitness and/or survival of populations due to increased inbreeding |
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Genetic drift |
stochastic fluctuations in allele frequencies due to random sampling of gametes each generation offspring receive 1 allele from each parent by chance, some alleles not passed to offspring, so alleles can 'drift' |
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genetic drift in small isolated populations |
genetic variation dominated by genetic drift |
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genetic drift in large populations |
genetic variation dominated by natural selection |
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Effective populations size (Ne) |
size of an idealized population exhibiting the same genetic properties as the one being studied |
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Census population size (Nc) |
actual population size |
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Ne vs Nc |
Ne = 4NfNm / Nf+Nm = % of censused population |
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Over average Ne/Nc = |
0.11 |
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What can Ne be used for? |
to monitor the health of exploited/threatened/endangered species |
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Extinction vortex |
small pop -> inbreeding and genetic drift -> loss of genetic variability -> higher mortality and lower reproduction -> reduction in individual fitness and population adaptability |
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What can be done for small populations |
encourage habitat restoration prevent further habitat fragmentation develop habitat corridors to aid dispersal and gene flow genetic rehabilitation through translocations |
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Translocation example |
Florda panthers |
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Florida panthers |
declared endangered in 1967 by 1990s there were 20-25 adults left in Florida peninsula inbreeding depression so severe that often >1 genetic anomaly per individual |
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Translocation: Florida panthers |
extinction imminent translocation of 8 Texas puma females in 1995 assessed genetic health using 23 molecular markers: pre vs post-translocation population |
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Genetic risks from translocation |
mixing? can avoid inbreeding depression not mixing? can cause losses in genetic diversity outbreeding depression population homogenization reverse speciation |
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outbreeding depression |
reduced fitness from mating of unrelated individuals |
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reverse speciation |
hydribization and homogenization of genome |
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Critical information for management of endangered species |
population structure population connectivity effective population size |
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population structure |
number and arrangement of populations within landscape |
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population connectivity |
metapopulation structure |
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effect population size |
inherent fitness component |
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Effective population size is useful for... |
as a metric of vulnerability |
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SGD (standing genetic diversity) |
may enable evolution and adaptability |