Meeting Abstract

116.2  Saturday, Jan. 7  Evolution of thermal acclimation in constant and heterogeneous environments CONDON, CH*; COOPER, BS; YEAMAN, S; ANGILLETTA, MJ; Arizona State University; Indiana University, Bloomington; University of British Columbia; Arizona State University

Experimental studies of the evolution of thermal acclimation are dominated by tests for an adaptive benefit of acclimation under all conditions, an idea known as the beneficial acclimation hypothesis (BAH). Empirical support for the BAH is relatively weak, perhaps unsurprisingly, given the underlying assumption that acclimation is both cost-free and unperturbed by environmental heterogeneity. In this study, we compared the BAH to two alternative hypotheses that predict the evolution of acclimation capacity is affected by thermal heterogeneity among generations and non-adaptive processes such as gene flow among environments. We examined the evolution of developmental acclimation within twenty selection lines of Drosophila melanogaster evolving for over three years to constant and fluctuating thermal environments. Five replicated populations evolved in each of the four selection treatments: constant high (25 °C ) and low (16 °C) environments, a treatment where temperature fluctuated between 16 and 25 °C among generations and a second fluctuating treatment where gene flow was maintained between populations exposed to 16 and 25 °C. We raised female D. melanogaster at 16 and 25 °C and measured a reaction norm for daily fecundity for 10 isofemale lines within each of the selection lines.