In a HW population of butterflies the frequency of striped b

In a H-W population of butterflies, the frequency of striped butterflies is 0.9 and the frequency of spotted butterflies is 0.1. Assume the pattern is determined by two alleles of one gene.

a. What genotype frequencies do you expect if striped is the dominant trait?

b. What genotype frequencies do you expect if spotted is dominant?

Solution

a). Assuming that striped is the dominant allele and the gene coding for striped is, S. The frequency of S = 0.9

The frequency of spotted allele is s, and its frequency is = 0.1

The genotype frequencies is, SS (striped) = 0.9*0.9 = 0.81

The genotype heterozygotes is, Ss (striped) = 2*0.9*0.1 = 0.18

The genotype of homozygous recessive butterflies, ss (spotted) = 0.1*0.1 = 0.01

b). Assuming that spotted is the dominant allele and the gene coding is, S. The frequency of S = 0.1

The frequency of striped allele is s, and its frequency is = 0.9

The genotype frequencies is, SS (spotted) = 0.1*0.1 = 0.01

The genotype heterozygotes is, Ss (striped) = 2*0.9*0.1 = 0.18

The genotype of homozygous recessive butterflies, ss (spotted) = 0.9*0.9 = 0.81