Selection for starvation resistance in Drosophila melanogaster: physiological correlates, enzyme activities and multiple stress responses

Correlated responses to artificial selection for stress tolerance can provi de insight into underlying genetic variation and the physiological basis of stress resistance. Lines of Drosophila melanogaster held in the absence of food or with an unsuitable resource, specifically decomposing lemon, respo nded to selection by becoming starvation resistant. The lemon-selected line s also adapted by evolving a resource-based induction response. Compared to control lines, the selected lines tended to store more lipid, develop slow er and have a larger body size. Additional responses included resistance to desiccation and acetone fumes, suggesting multiple stress resistance is a correlated result of selection for starvation resistance. The specific meta bolic rate was lower in the starvation selected lines and enzyme activities changed in response to selection. In particular, enzyme activities indirec tly associated with lipid biogenesis increased in both types of selected li nes. The correlated responses to the two selection regimes were sufficientl y consistent to indicate a common basis for starvation resistance. Specific responses to starvation selection appeared to oppose the short-term phenot ypic responses to starvation. Thus, a common response to stress selection m ay be to ameliorate the immediate physiological impact of the stress factor .