CONSEQUENCES OF HOMOSPECIFIC AND HETEROSPECIFIC RAPID REMATING ON THEFITNESS OF DROSOPHILA-MELANOGASTER FEMALES

Remating of recently mated females of Drosophila melanogaster has been investigated in crosses involving two homospecific males and in cross es in which one male was from D. melanogaster and the other from its s ibling species D. simulans. Results indicate that if intensively court ed, females are able to remate one day after the first mating, When do uble matings occur firstly with D, melanogaster or D. simulans and sec ondly with D, melanogaster, around 80% of the first male sperm is lost and the remaining sperm mixes randomly with that of the second male, However, most D. melanogaster sperm is lost when double matings occur with D, melanogaster followed by D, simulans, which suggests some inco mpatibility between the D, melanogaster sperm and the D. simulans semi nal fluids, Fitness of D. melanogaster females remating homospecifical ly is higher than that of singly mated females. Also, the fitness of a female hybridizing with D. simulans and then remating with a male of its own does not differ from that of singly mated females, indicating that the negative effects of the hybridization can be surmounted by ra pid homospecific remating. These results indicate that early female re mating has an adaptive value for the D. melanogaster female.