FA2011lecture18

FA2011lecture18 - Main point: inbreeding increases the...

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Main point: inbreeding increases the proportion of homozygotes relative to heterozygotes, but does not by itself change allele frequencies over time (will see later that other violations of Hardy-Weinberg conditions do)
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Extreme example: effects of selfing on genotypic frequencies 0 0 1 0 1 0.25 0.50 0.25 2 0.25 + 0.125 = 0.375 0.25 0.25 + 0.125 = 0.375 3 0.4375 0.125 0.4375 4 0.469 0.062 0.469 5 0.484 0.031 0.484 n [1-(0.5) n ]/2 (0.5) n [1-(0.5) n ]/2 generation AA Aa aa NON-RANDOM MATING Inbreeding: mating between related individuals… increases proportion of AA and aa homozygotes relative to heterozygotes
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INBREEDING COEFFICIENT F = probability of being homozygous by descent (having two copies of same allele inherited from mother and father’s common ancestor) A 1 A 2 A 3 A 4 A 1 A 1 A 1 A 1 A 1 A 1 1/2 1/2 1/2 1/2 1/2 1/2 p(hbd A 1 A 1 ) = (1/2) 6 p(hbd A 2 A 2 ) = (1/2) 6 overall p(hbd) due to common ancestor A 1 A 2 = (1/2) 6 + (1/2) 6 = (1/2) 5 assuming max possible genetic diversity among
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FA2011lecture18 - Main point: inbreeding increases the...

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