Chapter 21, Problem 24P

In Drosophila, the vestigial wings recessive allele, vg, causes the wings to be very small. A geneticist crossed some true-breeding wild-type males to some vestigial virgin females. The male and female F₁ flies were wild type. He then allowed the F₁ flies to mate with one another and found that 1/4 of the male and female F₂ flies had vestigial wings. He dumped the vestigial F₂ flies into a morgue and allowed the wild-type F₂ flies to mate and produce an F₃ generation.

a.	Give the genotype and allele frequencies among the wild-type F2 flies.
b.	What will be the frequencies of wild-type and vestigial flies in the F3?
c.	Assuming the geneticist repeated the selection against the vestigial F3 flies (that is, he dumped them in a morgue and allowed the wild-type F3 flies to mate at random), what will be the frequency of the wild-type and mutant alleles in the F4 generation?
d.	Now the geneticist lets all of the F4 flies mate at random (that is, both wild-type and vestigial flies mate). What will be the frequencies of wild-type and vestigial F5 flies?