Whenever diploid populations are in hardy-weinberg equilibrium at a particular locus

Explanation:

Hardy Weinberg equilibrium states that in a population, the sum of allelic frequencies as well as genotypic frequencies remains same over generations

There are five assumptions regarding this equilibrium: there should be random mating, no immigration and emigration, no mutation, no natural selection and population should be large and non evolving

Whenever diploid populations are in Hardy Weinberg equilibrium at a particular locus the allele's frequency should not change from one generation to the next, but its representation in homozygous and heterozygous genotypes may change