REMATING AND MALE-DERIVED NUTRIENTS IN DROSOPHILA-MELANOGASTER

Laboratory natural selection and environmental manipulations were used to investigate the importance of male-derived nutrients to female Dro sophila melanogaster. No evidence for the importance of such nutrients was found. Females from the same wild type base stock exposed as adul ts to low quality food did not show elevated fecundity or survival whe n they remated more frequently, and on high quality food the females s howed a 'cost of mating' in reduced survival. Laboratory evolution on low quality food did not lead to elevated rates of remating by females ; females from each selection regimen remated more frequently than one another when kept on the food type to which they had been exposed for the previous 5 years, on which they also showed higher fecundity than one another. Even under conditions of extreme nutritional stress, whe n females were exposed to short term (4-day) cycle of exposure to very low and high quality food, they remated more frequently immediately a fter exposure to high quality food. The results of this last experimen t suggested that, under these circumstances, current nutrition, fecund ity or rate of sperm usage was more important than number of sperm in store or cumulative fecundity in determining the probability that a fe male would remate.