Genetical Research

Research Article

The transient distribution of allele frequencies under mutation pressure

Masatoshi Neia1 and Wen-Hsiung Lia1

a1 Center for Demographic and Population Genetics, University of Texas at Houston, Texas 77030


The transient distribution of allele frequencies in a finite population is derived under the assumption that there are k possible alleic states at a locus and mutation occurs in all directions. At steady state this distribution becomes identical with the distribution obtained by Wright, Kimura and Crow when k = ∞. The rate of approach to the steady state distribution is generally very slow, the asymptotic rate being 2v + 1/(2N), where v and N are the mutation rate and effective population size, respectively. Using this distribution it is shown that when population size is suddenly increased, the expected number of alleles increases more rapidly than the expected heterozygosity. Implications of the present study on testing hypotheses for the maintenance of genetic variability in populations are discussed.

(Received November 28 1975)