Sex and genetic variation interact to modify the response of Drosophila melanogaster to metal stress.

Abstract

Organisms are under nearly continuous stress from anthropogenic contaminants, but the molecular response mechanisms, particularly the variation in these responses, are not well understood. Nickel (Ni) contamination, often associated with mining activity, is known to cause a series of health effects, but surprisingly little is known about individual variation in Ni response. In this study, we quantified the mortality response of Drosophila melanogaster to environmental Ni across a series of lines and both sexes and compared it with that of copper (Cu), a well-characterized metal contaminant. Ni exposure had substantial negative effects that were significantly modified by sex, line, and interactions between the two. Strikingly, these trends in differential responses between the sexes and lines were mirrored in both Ni and Cu. Variation in Ni-driven mortality was correlated with starvation resistance, but not with Ni body burden. This contrast suggests a possible role of starvation resistance, but not body burden, in differential mortality. Across all experiments, sex and line effects were not independent; the level of sexual dimorphism varied significantly and substantially across lines, and line effects differed between the sexes. Overall, the results of this study highlight the fact that an understanding of biology requires examination of both sexes and multiple lines.