Population Genetics

# A 92 b 64 c 8 d 4 e 1 properties of genetic

• Notes
• 92

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a) 92% b) 64% c) 8% d) 4% e) 1%

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Properties of Genetic Equilibrium 1) maximum heterozygosity,H, is attained when p=q Take dH=2(1-q)q, with regard to q dH/dq=d(2q-2q 2 )/dq=2-4q, Set d=0 (maximum likelihood function) Solve for q, Then q=.50
Properties of Genetic Equilibrium 2) As p,q values move away from equality, H class diminishes Where 2pq=p 2 , 2p(1-p)=p 2 , then p=2/3 Beyond which p 2 >2pq >q 2

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Properties of Genetic Equilibrium 3) As rarer allele becomes less frequent, H class carries greater proportion of that allele than do homozygotes. H/R = 2pq/q2, = 2p/q
Who has Q? q q 2 2pq 2pq/q 2 .5 .25 .50 2 .1 .01 .20 20 .01 .0001 .02 200 .001 .000001 .002 2000

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Properties of Genetic Equilibrium 4) Among 3 parental matings that produce aa offspring, the relative proportions of aa produced are in same proportions as the zygote frequencies predicted by the square law. aa GT Among Relative Parent Mating All offspring frequencies Aa x Aa p 2 q 2 p 2 Aa x aa 2pq 3 2pq aa x aa q 4 q 2 Total q 2 1.0
What Assumptions? Large population Random mating No mutation No migration No selection

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Effects on allele/gt frequencies when there are deviations from H-W assumptions Non-random mating population substructure inbreeding (increases homozygosity) • Mutation introduction of new alleles new allele frequencies affected by selection, drift • Migration – drift founder effects Small population size random drift • Selection can alter relative allele frequencies