Mortality from desiccation contributes to a genotype-by-temperature interaction for cold survival inDrosophila melanogaster

Abstract

SUMMARYSurvival at cold temperatures is a complex trait, primarily because of the fact that the physiological cause of injury may differ across degrees of cold exposure experienced within the lifetime of an ectothermic individual. In order to better understand how chill-sensitive insects experience and adapt to low temperatures, we investigated the physiological basis for cold survival across a range of temperature exposures from −4 to 6°C in five genetic lines of the fruit fly Drosophila melanogaster. Genetic effects on cold survival were temperature dependent and resulted in a significant genotype-temperature interaction for survival across cold temperature exposures that differ by as little as 2°C. We investigated desiccation as a potential mechanism of injury across these temperature exposures. Flies were dehydrated following exposures near 6°C, whereas flies were not dehydrated following exposures near −4°C. Furthermore, decreasing humidity during cold exposure decreased survival, and increasing humidity during cold exposure increased survival at 6°C, but not at −4°C. These results support the conclusion that in D. melanogaster there are multiple physiological mechanisms of cold-induced mortality across relatively small differences in temperature, and that desiccation contributes to mortality for exposures near 6°C but not for subzero temperatures. Because D. melanogaster has recently expanded its range from tropical to temperate latitudes, the complex physiologies underlying cold tolerance are likely to be important traits in the recent evolutionary history of this fruit fly. Supplementary material available online at

Basal tolerance to heat and cold exposure of the spotted wing drosophila,Drosophila suzukii

“…S2). In D. melanogaster , the humidity during both heat (Bubliy et al, 2012) and cold exposure (Kobey & Montooth, 2013) alters survival rate. Combining two stressors like high temperature with low RH provides more stressful conditions to vinegar flies than high temperature with high RH (Bubliy et al, 2012).…”

“…Since invasion process may trigger adaptation to novel climatic areas, data are highly needed on invasive populations submitted to a range of thermal stress intensities and durations. In Drosophila melanogaster , the humidity during thermal stress modifies survival probability and the response can be temperature-dependent (Bubliy et al, 2012; Kobey & Montooth, 2013). Combining high temperature with low humidity provides more stressful conditions to Drosophila flies than high temperature with high humidity (Bubliy et al, 2012).…”

“…Combining high temperature with low humidity provides more stressful conditions to Drosophila flies than high temperature with high humidity (Bubliy et al, 2012). Furthermore, increasing humidity during cold exposure increased survival at 6 °C, but not at −4 °C in D. melanogaster (Kobey & Montooth, 2013). This underlines that interaction among abiotic factors may be complex.…”

Hemolymph metabolites and osmolality are tightly linked to cold tolerance ofDrosophilaspecies: a comparative study

“…Further, it has previously been shown that dehydration exacerbates the development of chill injury in D. melanogaster, particularly at moderate cold exposure temperatures (Kobey and Montooth, 2013). It should be mentioned, however, that the water vapor deficit is very low during the cold exposure and the flies are therefore unlikely to be severely stressed by dehydration during short-term exposures (Kobey and Montooth, 2013). Secondly, it is possible that dissipation of osmotic gradients occurs within the animal as a consequence of reduced active transport at low temperatures.…”

“…Indeed, tropical (and cold-sensitive) Drosophila species are generally also more susceptible to dehydration than xeric or coldadapted species (Kellermann et al, 2013). Further, it has previously been shown that dehydration exacerbates the development of chill injury in D. melanogaster, particularly at moderate cold exposure temperatures (Kobey and Montooth, 2013). It should be mentioned, however, that the water vapor deficit is very low during the cold exposure and the flies are therefore unlikely to be severely stressed by dehydration during short-term exposures (Kobey and Montooth, 2013).…”