Selection for adult desiccation resistance in Drosophila melanogaster: fitness components, larval resistance and stress correlations

In previous experiments we found that Drosophila melanogaster lines selected for increased adult desiccation resistance had increased resistance to other environmental stresses at the adult stage including starvation, intense 60Co-γ radiation and a toxic ethanol level. In further studies on these lines, we now show that selection did not alter resistance to desiccation and ethanol at the larval stage. As well as having a lower early fecundity, selected lines showed increased adult male longevity and increased viability at high larval densities compared with control lines. There were no changes in development time or mating success. The increased male longevity is consistent with the reduced metabolic rate of the selected lines. A genetic correlation between resistance to different stresses was confirmed by an analysis of isofemale lines derived from a population founded by flies from a stress-resistant line and an unselected line. The results are consistent with the existence of genes segregating in natural populations conferring increased general stress resistance.