Industrial melanism refers to dark pigmentation that evolved

Industrial melanism refers to dark pigmentation that evolved in some insects, giving them protective coloration on vegetation darkened by soot in heavily industrialized areas prior to the requirement for smokestack filtration. In one heavily polluted area near Birmingham. England in 1956. 79% of the moths of the species Biston betularia had black bodies due to the presence of a dominant gene for melanism. Of the melanistic individuals, what percentage is heterozygous?

Solution

79% species had dark coloration. This according to HW equilibrium = \"BB\" genotypes + \"Bb\" genotypes = p2+ 2pq

So, 21% species had light coloration = \"bb\" genotypes = q2 = 0.21

q = (.21) = 0.46

p = (1-q) = (1-0.46) = 0.54

Percentage of heterozygous species = 2pq = 2*0.54*0.46 = 0.4949

49.5% species are heterozygous