Genetics and Genomics

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Selection Changes Allele Frequency


Selection is the process that dictates which individuals become parents and how prolific the parents will be. Consider a deleterious recessive condition that confers 40% reduction in the viability of homozygous recessive genotypes (s = 0.40), which could occur through reduced survival, reduced fertility, or some combination of the two.

Genotype AA Aa aa
Fraction removed due to selection 0 0 s = 0.40
Fraction remaining after selection 1 1 1 – s = 0.60

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Assume that the A allele frequency is 0.850 (and therefore the a allele frequency is 0.150) in the progeny generation and that the progeny were produced from random mating.