Natural selection – changing allele frequency (peppered moth)

BiologyEvolutionAges 17–18

A moth population rests on tree trunks: genotypes AA and Aa give dark wings, aa gives light wings, and each genotype has its own fitness (survival rate to reproduction). Each generation, individuals are removed according to fitness, alleles are passed on, and A ⇄ a mutation occurs at a small rate; a graph tracks allele frequency across generations against the theoretical Δp curve. Students drag the fitness values, switch the bark color to reverse the direction of selection, and watch the favored allele rise over time.