genetic equilibrium

Genetic equilibrium, as described by the Hardy-Weinberg law, is a principle in population genetics. It states that in a large, randomly mating population, the proportions of dominant and recessive genes, and thus the genetic makeup of the population, remain constant from one generation to the next unless acted upon by outside forces. These forces, which can disrupt the equilibrium and drive evolution, include selection, mutation, and migration.1

The law is expressed algebraically, with p representing the frequency of a dominant allele and q representing the frequency of a recessive allele. In equilibrium, the genotype frequencies are p² for homozygous dominants, 2pq for heterozygotes, and q² for homozygous recessives. This principle serves as a baseline for understanding evolutionary change, as any deviation from these proportions indicates that evolution is occurring.21