Hardy-weinberg

Science

Definition

The Hardy-Weinberg principle states that allele and genotype frequencies in a population remain constant from generation to generation in the absence of evolutionary influences. It serves as a null hypothesis for detecting whether evolution is occurring in a population.

Examples

  • If 16% of a population shows a recessive phenotype, q² = 0.16, so q = 0.4 and p = 0.6
  • Researchers compare observed genotype frequencies to Hardy-Weinberg expectations to detect natural selection in wild populations
  • A population of beetles on an isolated island can be tested for Hardy-Weinberg equilibrium to see if selection is acting on shell color
Key Fact

p² + 2pq + q² = 1 and p + q = 1; requires no mutation, no selection, random mating, large population, and no gene flow.

Related Terms

Natural selection Mendelian genetics Evolution

Study This Concept

Practice Hardy-Weinberg with free review games in these units:

AP Biology Unit 7: Natural Selection