What is the role of the Hardy-Weinberg principle in population genetics?

The Hardy-Weinberg principle is essential in population genetics because it predicts allele and genotype frequencies in a population that is not undergoing evolutionary change. When a population meets the criteria of the Hardy-Weinberg equilibrium—such as no mutations, random mating, no gene flow, infinite population size, and no selection—the principle provides a baseline expectation for how gene frequencies should behave over generations.

This framework allows researchers to determine whether or not a population is evolving. If observed frequencies deviate from what is predicted by the Hardy-Weinberg equilibrium, it suggests that evolutionary forces such as selection, genetic drift, migration, or non-random mating are acting on the population. Thus, the role of the Hardy-Weinberg principle is foundational in establishing a starting point for understanding genetic variation and evolution within populations.