Zygotic associations and multilocus statistics in a nonequilibrium diploidpopulation

The usual approach to characterizing and estimating multilocus associations in a diploid population assumes that the population is in Hardy-Weinberg e quilibrium The purpose of this study is to develop a set of summary statist ics that can be used to characterize and estimate the multilocus associatio ns in a nonequilibrium population. The concept of "zygotic associations" is first expanded to facilitate the development. The summary statistics are c alculated using the distribution of a random variable, the number of hetero zygous loci (K) found in diploid individuals in the population. In particul ar, the variance of K consists of single-locus and multilocus components wi th the latter being the sum of zygotic associations between pairs of loci. Simulation results show that the multilocus associations in the variance of K are detectable in a sample of moderate size (greater than or equal to 30 ) when the sum of all pairwise zygotic associations is greater than zero an d when gene frequency is intermediate. The method presented here is a gener alization of the well-known development for the Hardy-Weinberg equilibrium population and thus may be of more general use in elucidating the multilocu s organizations in nonequilibrium and equilibrium populations.