The Hardy-Weinberg principle, also known as the Hardy-Weinberg equilibrium, is a principle in population genetics that states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of disturbing factors. The principle is based on five assumptions, which are:
- Organisms are diploid.
- Only sexual reproduction occurs.
- Generations are non-overlapping.
- Mating is random.
- Population size is infinitely large.
- Allele frequencies are equal in the sexes.
- There is no migration, gene flow, admixture, mutation, or selection.
If these assumptions are met, the genotype and allele frequencies will remain constant from one generation to the next. However, in reality, the Hardy-Weinberg equilibrium is rarely achieved due to various factors such as mutations, natural selection, non-random mating, genetic drift, and gene flow.
The Hardy-Weinberg equilibrium is a neutral equilibrium, which means that a population perturbed from its Hardy-Weinberg genotype frequencies will reach equilibrium after a single generation of random mating, but it will be a new equilibrium if allele frequencies have changed. The equilibrium is not stable, and a change from the equilibrium genotype frequencies will generally be associated with a change in allele frequencies.
The Hardy-Weinberg principle is important because it provides a baseline to compare how an evolving population could compare to one that remains constant without evolutionary forces acting upon it. The principle also has practical applications in fields such as forensics, where it can be used to estimate the frequency of alleles in a population.
