Sex-specific differences in the physiological basis of water conservation in the fruit fly Drosophila hydei from the western Himalayas
2014
Parkash, Ravi | Singh, Divya | Lambhod, Chanderkala
In the cosmopolitan fruit fly Drosophila hydei Sturtevant, 1921 (Diptera: Drosophilidae), the relative abundance of males is significantly higher than females, but the physiological basis of such sex-specific differences are largely unknown. For wild populations of D.hydei, we found seasonal changes (summer versus autumn) in desiccation-related traits, but the desiccation tolerance of males was higher than that of females in all seasons. For desiccation-related traits, we tested whether thermal developmental acclimation at three temperatures (17, 21, and 28 °C) matched seasonal changes observed under wild conditions. Male flies showed significantly higher trait values for desiccation resistance, cuticular lipid mass, hemolymph content, carbohydrate content, and dehydration tolerance compared with females when reared at lower or higher temperatures despite the lack of significant sex-specific differences in the total body-water content of flies reared at a particular growth temperature. We observed plastic changes in the amount of cuticular lipids consistent with corresponding differences in the rate of water loss. Treatment of cuticular surface with organic solvent (hexane) supported the role of cuticular lipids in affecting transcuticular water loss. We found significant thermal plastic effects for desiccation-related traits of D.hydei, but the sexual dimorphism was in the opposite direction, i.e., males were more desiccation resistant than females in D.hydei, whereas the reverse is true for many other Drosophila species. Our results suggest that sex-specific differences in the level of desiccation resistance in D.hydei are good predictors of relative abundance levels of male and female flies under wild conditions.
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