Evolution of cross-tolerance to environmental stresses in populations of Drosophila melanogaster selected for increased resistance to cold stress

Abstract

AbstractEmpirical studies on the promiscuous species of Drosophila revealed that the laboratory evolution of resistance to a certain type of environmental stress can impact the ability of the organism to resist other kinds of stresses. The mechanisms of resistance to a particular stress are specialized and costly, then, mechanisms of resistance to other stresses can be negatively affected. However, it is also possible that at least a part of the stress resistance mechanisms is generic. With this premise we aimed to understand whether increased resistance to a cold stress can increase resistance to other types of stresses.To address this issue, we used populations of Drosophila melanogaster (D. melanogaster) that have been selected for 57-71 generations for increased resistance to cold shock (−5°C for one hour). We subjected the selected (FSB; selected for cold shock resistance, derived from BRB population) and control FCB; cold shock control, derived from BRB population) populations to a variety of environmental stresses such as cold shock, heat shock, starvation, desiccation and bacterial infection. We found that the compared to FCB populations, FSB populations had higher resistance to heat stress in terms of adult survivorship and mating ability post cold or heat shock. Desiccation resistance was observed higher in FSB females compared to FCB females but no such difference was found in males. We observed that FSB populations had lower starvation resistance relative to FCB populations. There was no difference between FSB and FCB populations in their ability to survive post bacterial infection. Our findings suggest that resistance to heat stress and desiccation (in females) are positively correlated with increased resistance to cold shock. However, resistance to starvation was negatively correlated with increased resistance to cold shock.