Oviposition in the period genotypes of Drosophila melanogaster.

Two behavioral rhythm phenotypes, oviposition and locomotor activity, have been compared in the four period genotypes (per+, pers, per0, and per1) of Drosophila. Period, signal-to-noise ratio, and phase were all analyzed and the genetic penetrance of the two characters was estimated. Significant rhythmicity of both oviposition and locomotor activity was evident in all four genotypes. The entrained and free-running periods of the activity rhythms of per+, pers, and per1 were within the range reported for these flies by previous workers, and rhythmic behavior was also shown by the per0 flies. The free-running period of the oviposition rhythm varied similarly between the four genotypes and showed significant correlation with that of the locomotor activity rhythm. It is suggested that both rhythm phenotypes are determined by the period gene, and estimates of the genetic penetrance of rhythmicity in oviposition and locomotor activity, based on period and signal-to-noise ratios (SNRs) of the different strains, are consistent with this hypothesis. The phase of maximum oviposition and locomotor activity showed greater variability between the genotypes and was not significantly correlated with period, suggesting that this rhythm characteristic is independent of mutations at the period locus.