Figure 15.11: Calculating Allele and Genotype Frequencies Allele and genotype frequencies for a gene locus with two alleles in the population can be calculated using the equations in panel 1. When the equations are applied to two populations (panel 2), we find that the frequencies of alleles A and a in the two populations are the same, but the alleles are distributed differently between heterozygous and homozygous genotypes.