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Published byFarida Makmur Modified over 6 years ago
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What is the frequency of A1 in the next generation?
p2w11 + pqw12 pt + 1 = p2w11 + 2pqw12 + q2w22 What is the change in frequency of A2 per generation? After some algebra Dp = pt pt = p / w (pw11 + qw12 - w ) With this equation we can substitute values for relative fitness and analyze various cases of selection.
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Gene Action Fitness Relationship A1A1 A1A2 A2A2 1 + s 1 + s 1
Dominance A1A1 A1A2 A2A2 1 + s Recessivity A1A1 A1A2 A2A2 1 + s t Overdominance A1A1 A1A2 A2A2 1 + s t Underdominance
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Dominance Genotype A1A1 A1A2 A2A2 Fitness 1 + s s S = 0.01 A1
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Recessive Genotype A1A1 A1A2 A2A2 Fitness 1 + s S = 0.01 A1
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Evolution in lab populations of flour beetles support theoretical predictions. Dawson (1970)
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Overdominance/Heterozygote Superiority
Genotype A1A1 A1A2 A2A2 Fitness 1 + s t S = t = Stable equilibrium is reached A1 Genetic diversity is maintained
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Viable allele did not fix in the population
Mukai and Burdick 1958
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Underdominance Genotype A1A1 A1A2 A2A2 Fitness 1 + s t S = t = 0.02 Unstable equilibrium A1 A1 maybe fixed or lost from the population
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Frequency-Dependent Selection
Allele frequencies in a population remain near an equilibrium because selection favors the rarer allele. As a result, both alleles are maintained in the population. Perissodus
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12.14(2) Multiple-niche polymorphism in the black-bellied seedcracker
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12.12 Gene flow reduces adaptation to fish predation among larvae of a salamander
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12.7(1) Plots of mean fitness (v) against allele frequency (p) for one locus with two alleles
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12.7(2) Plots of mean fitness (v) against allele frequency (p) for one locus with two alleles
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12.7(3) Plots of mean fitness (v) against allele frequency (p) for one locus with two alleles
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12.7(4) Plots of mean fitness (v) against allele frequency (p) for one locus with two alleles
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12.20(1) A peak shift due to the joint action of genetic drift and natural selection
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12.20(2) A peak shift due to the joint action of genetic drift and natural selection
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