Suppose variants at a single locus affect wing length in a species of crickets, with homozygotes for the L allele having long wings, homozygotes for the l allele having short wings, and heterozygotes having wings of intermediate length.In one population of 600 individuals, 400 have long wings, 160 have intermediate-lengths wings, and 40 have short wings.What is the expected number of individuals with long wings under Hardy-Weinberg equilibrium?
A) 216
B) 300
C) 384
D) 400
E) 480

Question

Quizplus · Accepted Answer

To find the expected number of individuals with long wings under Hardy-Weinberg equilibrium, we first need to calculate the allele frequencies. Given that 160 individuals have intermediate-length wings (heterozygotes), we can deduce that 2pq = 160/600 = 0.267, where p is the frequency of the L allele and q is the frequency of the l allele. Since p + q = 1, we can solve for p and q. However, a quicker way to estimate p and q given the information is to recognize that the number of homozygotes provides a direct way to calculate allele frequencies. The 40 individuals with short wings are homozygous recessive (ll), so q^2 = 40/600 = 1/15. Thus, q = sqrt(1/15) ≈ 0.258. Since p + q = 1, p ≈ 1 - 0.258 = 0.742. The expected number of individuals with long wings (LL) under Hardy-Weinberg equilibrium is p^2 * total population = (0.742)^2 * 600 ≈ 384.

Suppose Variants at a Single Locus Affect Wing Length in a Species