Hardy-Weinberg principle

The Hardy-Weinberg principle was independently proposed by mathematician G.H. Hardy and physician Wilhelm Weinberg at the beginning of the 20th Century. They stated that a population should be in equilibrium with respect to a specific gene as long as five conditions hold:

  1. The population is so large that random changes in the allele frequency are negligible.
  2. No new mutations are affecting the gene;
  3. The gene does not influence survival or reproduction, so that natural selection is not occurring;
  4. Gene flow, or the change in allele frequency due to migration into and out of the population, is negligible.
  5. Mating occurs randomly with respect to the gene of interest.

Of course, these principles do not always hold. For example, small populations may exhibit wide shifts in allelic frequencies solely due to random changes arising from genetic drift.