Hardy weinberg 1-2

Hardy weinberg equilibrium. mathematical model in population genetics that reflects the relationship between frequencies of alleles and of genotypes. it can be used to determine if a population is undergoing evolutionary changes.

Godfry Hardy & Wilhelm Weinberg.
if no mutation, or natural selection or gene flow happens, if the population is large, if mating is random and all members of population produce the same number of offspring then genotype frequencies at a single gene locus will remain the same after one generation.
Equilibrium frequencies will be a function of allele frequency at the locus.
Application. by studying genotype frequencies of a population in different time we can find if evolution is operating on that particular gene.