Data for an autosomal recessive trait shows that heterozygous individuals have the highest relative fitness. Those who are unaffected and homozygous for the dominant A allele have a relative fitness of 84% compared to heterozygous individuals, but only about 30% of those who are affected survived to reproduce. What is the estimated equilibrium frequency for allele A in this population?
A) 0.700
B) 0.160
C) 0.186
D) 0.814
E) 0.357

Question

Quizplus · Accepted Answer

The equilibrium frequency of allele A (p) in a population where heterozygotes have the highest fitness can be estimated using the formula p = sqrt(w_AA / w_AA + s), where w_AA is the relative fitness of the homozygous dominant genotype and s is the selection coefficient against the homozygous recessive genotype. Given that homozygous dominant individuals have a relative fitness of 84% (0.84) compared to heterozygotes, and only 30% of homozygous recessive individuals survive to reproduce, the selection coefficient against them is 1 - 0.30 = 0.70. Plugging these values into the formula gives an equilibrium frequency for allele A of approximately 0.186.

Data for an Autosomal Recessive Trait Shows That Heterozygous Individuals