LETHAL ALLELES IN MUS MUSCULUS: LOCAL DISTRIBUTION AND EVIDENCE FOR ISOLATION OF DEMES.

In the vicinity of Calgary, Alberta, 20.5 percent of wild house mice tested were found to be heterozygous for the lethal allele designated t(w5), and an additional 3.4 percent were heterozygous for one or more alleles not belonging to the t(w5) group. The distribution patterns of wild-type and lethal alleles within and between clusters of small demes supports the postulate that random drift plays a significant role in the evolution of these populations. Distribution patterns also suggest that the demes are reproductively isolated to a greater degree than has been generally assumed.