When the allele frequencies in a population remain constant from generation to generation, the population is said to be in Hardy-Weinberg equilibrium where there is no evolution. Such conditions are when there is a very large population size, no migration, no net mutations, random mating, and no natural selection.
In a very large population, genetic drift, which is the change in a population's allele frequencies due to chance, can cause genotype frequencies to change over time.
…
