The theory of population genetics is concerned with gene frequencies and genotype frequencies and with the processes influencing these frequencies.

Population genetics is the most important, most fundamental body of theory in evolutionary biology. It is the proving ground for almost all ideas in evolutionary biology: the coherence of an evolutionary hypothesis will usually remain in doubt until the hypothesis is expressed in the form of a population genetics model.

Given frequencies in generation n , an elementary population genetics model can be used to predict frequencies in generation n +1.