STABLE EQUILIBRIA IN MULTILOCUS GENETIC SYSTEMS - A STATISTICAL INVESTIGATION

A data base of gametic distributions at a stable equilibrium for genet ic systems with up to five diallelic loci was created by numerically i terating equations for the dynamics of gametic frequencies in multiloc us systems under selection. For a given number of loci, iterations wer e conducted for 4000 random sets of genotypic fitnesses, 6 values of r ecombination, and 10 different initial distributions. The data base wa s used to investigate the following properties of stable equilibria ma intaining a polymorphism in a given number of loci that are expected a priori, i.e., without any constraints an fitnesses of genotypes: prob ability for a fitness set to yield a such equilibrium; probability for a random trajectory to converge to a such equilibrium; genetic load a t a such equilibrium. The expected number of simultaneously stable equ ilibria, and the fraction of genome maintained polymorphic were also i nvestigated as well as some parameters expected at an equilibrium main taining all loci polymorphic. One of the most important findings is th at multilocus genetic systems have a potential for maintaining a polym orphism in a large number of loci under selection without an input of new genetic variation. (C) 1998 Academic Press.