A geneticist collected a population of 100 peppered moths. 36 were dark (DD or Dd) and 64 were light (dd). The alleles present in each moth were determined. Out of the 200 alleles for this gene present in this population, the gene pool contained 40 dark D alleles and 160 light d alleles. What are the allele frequencies for the two alleles in this population?

A) D = 0.36; d = 0.64

B) D = 0.50; d = 0.50

C) D = 0.25; d = 0.75

D) D = 0.20; d = 0.80

D) D = 0.20; d = 0.80

Explanation:

Ok, so first off, we know that the number of homozygous recessive individuals is 64. So 64/100 is the q^2 value. The q value is the square root of that: it is 0.8. Because p + q has to always equal 1, the p value is then 0.2, and the p^2 value 0.04.

So, we know that the heterozygotes had to be 0.16 of the population (1-0.8-0.04 = 0.16).

d has to equal 0.8 because it is the number of recessive alleles in the population, and they give you this too. D is 0.2.