Hardy–Weinberg Principle

A population-genetic principle stating that allele and genotype frequencies remain constant from generation to generation in an idealized randomly mating population in the absence of evolutionary forces (selection, mutation, migration, drift) and nonrandom mating.

In population genetics, the statement that, for a single autosomal locus in a large diploid population with random mating and no mutation, migration, selection, or genetic drift, allele frequencies remain constant between generations and the expected genotype frequencies for two alleles A and a are p^2, 2pq and q^2 (where p and q are allele frequencies).