Hardy-Weinberg Distribution

**Semantic type:** Conceptual Entity

**Definition:** The ratio of genotype frequencies that evolve when mating is random and neither selection nor drift are operating. For two alleles (A and a) with frequencies p and q, there are three genotypes: AA, Aa, and aa. The Hardy-Weinberg ratio for the three is: p^2AA : 2pqAa : q^2aa. Deviation from this ratio indicates that some force is acting on the population (e.g., selection, mutation, migration, genetic drift, non-random mating).

**Synonyms:** - Hardy-Weinberg Ratio