Population Subdivision

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Population Subdivision distribution of
organisms is not continuous - discrete
habitats - spatial heterogeneity
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Population Subdivision distribution of
organisms is not continuous - discrete
habitats - spatial heterogeneity
population subpopulations (deme) A1A1 A1A2 A
2A2 f(A1) deme 1 64 32 4
0.8 deme 2 4 32 64
0.2 total 68 64 68
0.5 Hexp, expected frequency of heterozygotes
0.5 but Hobs, observed frequency of
heterozygotes 0.32
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FST
FST 0 - 1
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FST
A1A1 A1A2 A2A2 f(A1) deme 1
64 32 4 0.8 deme 2 4
32 64 0.2 total 68 64
68 0.5
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FST increases with geographical separation
Forbes Boyd 1997
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Gene flow in reef building corals Vollmer
Palumbi 2006
A. palmata
Acropora cervicornis
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Vollmer Palumbi 2006
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Genetic Structure Gene NSC NST NCT mtD
NA 0.016 0.130 0.100 native
mtDNA -0.018 0.235 0.249 Nuclear DNA
0.041 0.067 0.027 Minicollagen
0.025 0.189 0.167 Calmodulin
0.013 0.021 0.008 PaxC 0.075 0.075 -0
.001
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Genetic Structure Gene NSC NST NCT mtD
NA 0.016 0.130 0.100 native
mtDNA -0.018 0.235 0.249 Nuclear DNA
0.041 0.067 0.027 Minicollagen
0.025 0.189 0.167 Calmodulin
0.013 0.021 0.008 PaxC 0.075 0.075 -0
.001
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Gene flow dispersal movement of individuals
between popns (necessary but not sufficient
for gene flow) gene flow individuals
leave their natal population reach new
suitable habitat successfully
reproduce infer dispersal from studies of
movement infer gene flow from allele frequency
patterns model as genetic exchange among
demes deme subpopulation that is
genetically connected to other subpopulations
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v
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Gene flow and local adaptation in sticklebacks
Hendry et al 2002
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( ) NS

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X
Release-recapture experiment stream
fish lake fish 1999 released 136
136 recaptured at release site
44 6 below release site
13 29 2000 released 135
134 recaptured at release site
43 21 belwo release site
15 25
Hendry et al 2002
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Hendry et al 2002
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disperal is necessary, but not sufficient, for
gene flow gene flow reduces among population
genetic variance gene flow can prevent
adaptation to local conditions the degree of
gene flow can be inferred from FST values,
provided there are also estimates of population
size