Meeting Abstract

85.2  Thursday, Jan. 7  Acclimation of thermal sensitivity in Drosophila melanogaster from high and low latitudes COOPER, B.S.*; CZARNOłęSKI, M.; ANGILLETTA, M.J.; Indiana University; Jagiellonian University; Indiana State University brascoop@indiana.edu

Organisms modify their physiological functions in response to changes in their environment, a process referred to as acclimation. Recent studies of acclimation have been influenced by verbal models, but these models cannot predict variation in acclimation capacity because they fail to consider the selective advantage of acclimation. We used a model of optimal developmental plasticity to generate predictions about the evolution of acclimation in Drosophila melanogaster. This model predicts that populations experiencing environmental variation among generations are more likely to evolve acclimating genotypes than are populations experiencing relatively constant environments. To evaluate this prediction, we compared the acclimation capacities of Drosophila melanogaster from two environments that differ markedly in thermal heterogeneity (Marlton, New Jersey and Miami, Florida); flies from New Jersey experience nearly twice as much among generation variation in body temperature and should developmentally acclimate to perform as adults. We raised flies from both populations in three thermal treatments and then measured their daily fecundity over a range of 14° to 36°C. Contrary to our prediction flies from both populations exhibited similar acclimation capacities. The fecundity of flies from both populations depended strongly on body temperature (P = < 0.001), but not in a way that can be predicted by theory. Flies produced the most eggs at 28° and 30°C regardless of their developmental environment. At all temperatures, flies that had developed in warm environments produced more eggs than flies that had developed in a cold environment. Our results suggest a need to refine current models of the evolution of developmental acclimation.