RUI: Collaborative Proposal: Biochemical and Physiological Adaptation to Temperature in a Montane Insect Herbivore

Santa Clara University, Santa Clara CA

Investigators

Abstract

This research investigates evolution in high elevation populations of the leaf beetle Chrysomela aeneicollis. Populations in the Sierra Nevada (California) are on the southern edge of the species' range. Previous studies found that drainages differ in air temperature and beetle populations fluctuate with changes in climate. Frequencies of different forms (genotypes) of the temperature-sensitive enzyme phosphoglucose isomerase (PGI) vary among drainages, suggesting that natural selection acts on PGI. Heat shock protein (Hsp) levels in beetles correspond to air temperature differences and depend on PGI genotype. The proposed research will investigate the relationship between temperature and functional property of PGI genotypes (i.e. their ability to catalyze biochemical reactions fundamental to metabolism). Second, the effects of temperature on the physiology of beetles of different PGI genotype will be studied, using Hsp's and ubiquitin conjugates as indices of physiological stress. Third, survival and reproduction of beetles of different PGI genotype in nature will be compared. The research will provide important information about the evolutionary significance of enzyme polymorphisms. It may add insight about the impact of climate change on native insects. Finally, it will allow undergraduates to participate in basic research, enhance their educational experience and expand their opportunities for the future