Meeting Abstract
Our current understanding of how physiological traits respond to divergent climates as species expand their geographic ranges is still limited. Invasive species currently undergoing range expansion provide unique opportunities to study how physiological traits may evolve in relation to climate as populations spread into different and possibly novel climates. In our study, we quantified variation in thermal physiology along the latitudinal range of the gypsy moth (Lymantria dispar) in North America. Specifically, we measured resting metabolic rates (RMR) of larvae from 14 wild populations across the invasion front, which span 11.5°C of latitude. For each population, RMR was assayed at three ecologically-relevant temperatures (15°C, 25°C, and 30°C). From these data, we estimated a least square mean, temperature-corrected RMR for each population and tested for differences as a function of latitude and local climate variables. This analysis revealed a significant positive relationship between RMR and latitude and a significant negative relationship between RMR and a suite of climate variables. Further analysis using multi-model inference revealed annual min. temperature to be the most significant predictor of population-specific RMR. Overall, the patterns were consistent with predictions made by the Metabolic Cold Adaptation hypothesis, with elevated RMR in colder climates. This study demonstrates the evolutionary potential of thermal physiology to evolve rapidly in response to changing climates. However, as the gypsy moth invasion reached warmer southern climates the invasion front has retracted possibly because this evolutionary potential has reached its limits in the south.
