Seasonal breeding structure in house fly, Musca domestica L., populations

Abstract

Allelic and genotypic frequencies were studied in four adult age groups of the common house fly. Electrophoresis was used to monitor allele frequencies at the Adh locus and three Amy loci at six farms on ten sampling dates from January to November 1983. No departures from random mating were noted. No differences in allele frequencies were found among sexes or age groups. Alleles at all loci showed seasonal trends. Frequency changes at Adh and Amy— loci were large and occurred in parallel among all farms. Changes in the Amy+ loci were small. At each locus, gene frequencies were statistically significantly different among farms, but differences were slight and not suggestive of strong local adaptation. Allele frequencies were stable from autumn to spring in the overall population, but frequencies monitored at a single farm drifted significantly from estimates in the founding autumn subpopulation. In spring, allele frequencies were heterogeneous among farms due to genetic drift during winter. This differentiation diminished rapidly in June. Spatial genie differentiation was pronounced among flies 0–3 days old, but older flies were panmictic. Seasonal trends in gene frequencies among farms were similar in 1982 and 1983.