Meeting Abstract
During winter, organisms are faced with multiple concurrent physiological challenges, including extreme cold and limited resources. During dormancy individuals rely on energy reserves accumulated during the resource-abundant summer months. Metabolic rate dictates rate of consumption of stored energy reserves, and is influenced strongly by temperature. For organisms that overwinter in subnivean (beneath-snow) spaces, temperature is modulated by snow cover, with snowy years being relatively warm and stable, while dry years are cold and variable. Snow thus alleviates the energetic cost of a stress response at the expense of a higher overall metabolic rate. Higher overall metabolic rate will deplete energy reserves, which are important because remaining reserves in spring determine future reproductive success. The willow beetle Chrysomela aeneicollis lives in high elevation habitats in the Sierra Nevada Mountains, where it overwinters in leaf litter below its host plant. To test the hypothesis that snow modulates winter energy use, we placed field-caught individuals under soil in plots exposed to natural snow cover or sheltered from snow. After seven months, survival was assessed and whole body lipid profile was measured using thin layer chromatography (TLC-FID). Survival did not differ between snow and no-snow conditions. Lipid stores decreased over the course of winter in both conditions, and beetles in the warmer, snowy conditions had significantly lower lipids at the end of winter compared to those exposed to environmental temperatures. This suggests that variation in snow cover will impact overwintering energetics of ectotherms.
