Sperm Utilization in Once- and Twice-Mated Drosophila pseudoobscura Females

Abstract

The effect of single mating and remating on sperm utilization in D. pseudoobscura females was investigated. Once-mated females produced progeny at a high level for 15 days; thereafter the number dropped significantly. Of the females, 72% remated within 6 days after the initial mating, when approximately 30% of the sperm was utilized. D. pseudoobscura females remate before sperm supply is exhausted. Remated females produced more progeny than once-mated females, regardless of the male genotype involved in matings. The increase occurred shortly after remating and diminished to the same level as that of once-mated females. Sperm competition was evident when the 2 male mates were of different genotype. The mean sperm displacement ability of ST;or/or males was 0.67 and for AR;+/+ males, 0.90. The 2 means were not statistically significant. In each case sperm displacement was evident.