THE EFFECTS OF REPRODUCTION ON LONGEVITY AND FERTILITY IN MALE DROSOPHILA-MELANOGASTER

We examined the effect of reproduction on subsequent survival and fecu ndity of male Drosophila melanogaster by reversing the reproductive st atus of individuals part-way through life. Reproduction had a much mor e marked effect on fertility than survival: males,vith a history of re production showed complete sterility at a time when upwards of 80% of their cohort were still alive. Analyses of survival rates alone gave a misleading measure of the impact of ageing. Sterility appeared to be attributable mainly to a reduction in sperm count. Early reproduction caused permanent, irreversible damage to both survival and fecundity, with risk playing an apparently minor role. Individual differences in frailty appeared to be of little consequence for the interpretation of these reversal experiments, although its possible occurrence made def inite detection of risk difficult. (C) 1997 Elsevier Science Ltd.