Population genetics of heterosis: Effects of Hardy-Weinberg disequilibrium

The mechanistic explanation of heterosis has been traditionally based on quantitative differences of gene effects. However, for outcrossing populations, heterosis is also a property of populations. In this paper, the effects of the deviation of a population from Hardy-Weinberg equilibrium (HWE) on the magnitude of heterosis have been examined numerically. The mating of two populations in HWE may generate directions and magnitudes of heterosis different from the mating of two populations in Hardy-Weinberg disequilibrium (HWD). Such differences of heterosis between these two types of population mating may be due to the release of vigor restored in the parental populations during the process of HWD. Results from this study can provide guidance on the selection of parental populations for the effective exploitation of heterosis and the prediction of genetic structure and organization for hybrid zones in nature.