Wahlund effect

A De Finetti diagram illustrating the Wahlund effect. The curved line are the Hardy–Weinberg equilibrium genotype frequencies; points 1 and 2 denote two populations in equilibrium. The genotype frequencies of the combined population are a weighted mean of the subpopulation frequencies, corresponding to a point somewhere on the solid line connecting 1 and 2. This point always has a lower heterozygosity (y value) than the corresponding (in allele frequency p) Hardy-Weinberg equilibrium.

In population genetics, the Wahlund effect is a reduction of heterozygosity (that is when an organism has two different alleles at a locus) in a population caused by subpopulation structure. Namely, if two or more subpopulations are in a Hardy–Weinberg equilibrium but have different allele frequencies, the overall heterozygosity is reduced compared to if the whole population was in equilibrium. The underlying causes of this population subdivision could be geographic barriers to gene flow followed by genetic drift in the subpopulations.

The Wahlund effect was first described by the Swedish geneticist Sten Wahlund in 1928.[1]

  1. ^ Wahlund, Sten (1928). "Zusammensetzung Von Populationen Und Korrelationserscheinungen Vom Standpunkt Der Vererbungslehre Aus Betrachtet". Hereditas. 11 (1): 65–106. doi:10.1111/j.1601-5223.1928.tb02483.x. ISSN 1601-5223.