Linkage Disequilibrium between Two Segregating Mutations in a Finite Population1 Nucleotide Sites under the Steady Flux Of

N our previous reports (OHTA and KIMURA 1969a, b, 1970), we have studied I linkage disequilibrium, that is, nonrandom association of genes between loci, caused by random frequency drift in finite populations. We have considered the situation in which a stationary distribution is reached under recurrent mutation or overdominance. We have also considered the case in which genetic variability decays each generation due to random sampling of gametes. The present paper is an extension of the work of KIMURA (1969a) who studied the number of heterozygous nucleotide sites under the steady flux of molecular mutations in a finite population. Here, we intend to study the amount of linkage disequilibrium between two segregating sites using the same model; it assumes that the total number of nucleotide sites making up the genome is so large and the mutation rate per site is so low that whenever a mutant appears, it represents a mutation at a previously homoallelic site, that is, a site in which no mutants are currently segregating in the population.