Question

Suppose a forest fire creates a habitat change such that where a lizard that has brown skin was formerly in Hardy-Weinberg equilibrium, natural selection by predators is creating a selective disadvantage for a dark brown allele. This allele (B) has been at a frequency of 0.9 and the light brown allele (b) has been at a frequency of 0.1. The allele is additive in its effect on the trait, and the new fitness levels of the genotypes after the fire are: BB = 0.4 Bb = 0.7 bb = 1.0 Based on these fitness values and initial genotype frequencies, we calculate a mean fitness of the population for the next generation of 0.46. Given this information, what is the frequency of the dark brown homozygote (BB) after 1 generation? Enter your answer as a percentage, not a decimal, but do not enter the % sign.

Answer 1

Answer:

70

Explanation:

mean fitness of the population for the next generation of 0.46

Allele frequency (p) for dark brown allele (B) =0.9

Frequency for dark brown homozygous phenotype after fire (BB) = 0.4

Frequency for dark brown homozygous (BB) after  1 generation;

= (p² × fitness level) / $W_{mean}$

= (0.9  ×  0.9 × 0.4 /  0.46)

= 0.704

= 70