Population genetics

Population genetics is the study of how allele frequencies change in populations over time under the influence of natural selection, genetic drift, mutation, and gene flow. Founded mathematically by Ronald Fisher, J. B. S. Haldane, and Sewall Wright in the 1920s and 1930s, it transformed evolutionary biology from a qualitative narrative into a quantitative science. The central equations — the Hardy-Weinberg equilibrium, Fisher's fundamental theorem, and Wright's fitness landscapes — describe how evolutionary forces shape genetic variation. Population genetics provides the mathematical bridge between Mendelian inheritance and Darwinian selection, but it has increasingly struggled to accommodate the complexity of gene regulatory networks and developmental processes that mediate the genotype-phenotype relationship.