Effects of Selection and Drift on the Dynamics of Finite Populations II. Expected Time to Fixation or Loss of an Allele

Abstract

Selection in a finite population (N) under the general two-allele one-locus model revealed the following. 1. When the favorable allele is recessive, the expected time to fixation is accelerated as compared with the case of no selection, s = 0. 2. When the favorable allele is dominant, there is a point in initial gene frequency, dependent largely on the product Ns and the degree of dominance, above which the time to fixation is accelerated and below which it is retarded as compared with the case of no selection. 3. For overdominance acceleration and retardation in the time to fixation as compared with no selection occurred respectively above and below the deterministic gene frequency equilibrium of 0.8. In all cases acceleration occurred for an interval of initial gene frequencies.