Relationships between wright's F ST and F IS statistics in a context of wahlund effect

Abstract

Waples (2015) has suggested a formula for the Wahlund effect in a case of unequal contribution of samples from genetically different populations that relates Wright's inbreeding coefficient, F IS, and normalized variance in allele frequencies between populations, F ST. I generalize this relationship to a case of multiple alleles and multiple populations not assuming Hardy-Weinberg ratios prior to mixing. This can help to evaluate the impact of a Wahlund effect on heterozygote deficiency relative to other factors such as null alleles, nonrandom mating, or selection. It is suggested that Wahlund effect cannot be an important factor of deviations from Hardy-Weinberg proportions in natural populations in the majority of instances, but it can have a substantial contribution to heterozygote deficiency in a population that has low genetic diversity compared to that among immigrants or in mixed samples that contain comparable fractions of individuals from genetically different populations.