Question

4 A lab population of cockroaches showed the following numbers of individuals of three genotypes, both among juveniles at the beginning of a generation, and (after some mortality) among pre-reproductive adults. (In other words, the adults are the same individuals as the juveniles...but obviously not all of the juveniles survived to adulthood!) AA | Aa | aa | Total Juveniles 540720 2401500 Adults 300550 150 1000 What are the relative fitnesses (w) and selection coefficients (s) for each of the three genotypes? (10 points)

Answer 1

Relative fitness is the reproductive rate of a genotype relative to maximum reproductive rate of other genotypes in a population

and

Selection coefficient is the relative strength of selection against a genotype

S = 1 - w

for juvenile calculating relative fitness

AA = 36%

Aa = 48%

aa = 16%

W(AA) = 36/48 = 0.75

W(Aa) = 48/48 = 1

W(aa) = 16/48 = 0.33

selection coefficient

S(AA) = 1 - 0.75 = 0.25

S(Aa) = 1 - 1 = 0

S(aa) = 1 - 0.33 = 0.67