Meeting Abstract
83-1 13:30 - 13:45 Damned if you do and damned if you don’t: adaptation to warmer environments leads to extinction in variable ones. Garcia Costoya, G*; Faske, TM; Moorman, JD; Logan, ML; University of Nevada, Reno; University of Nevada, Reno; University of California, Los Angeles; University of Nevada, Reno guille@nevada.unr.edu
The Earth’s mean surface temperature is predicted to increase by up to 4°C by 2100. Nonetheless, thermal variability, which represents a separate axis of environmental change, is also predicted to increase substantially. These two axes of variation represent independent challenges to ectothermic organisms, potentially generating antagonistic selection if the traits that confer high fitness in warmer environments on average confer low fitness in variable ones. In an ideal world organisms would simply evolve to thrive in both scenarios, but empirical evidence shows that thermal performance (represented by the thermal-performance curve or TPC) is often constrained via a generalist-specialist tradeoff. To address this issue, we developed a set of individual based simulations to explore the evolutionary responses of ectotherm populations whose TPC shapes are constrained to varying degrees by genetic correlations. We challenged these populations with several environmental change scenarios varying in the rate at which mean temperature and thermal variability changed relative to one another. In general, our simulations demonstrate an overwhelming tendency for populations to go extinct due to maladaptation. We found that extinction usually occurred because of the pressure to adapt to warmer mean temperatures in the earlier stages of environmental change led to the rapid evolution of thermal specialists, which became extinct after facing increasingly frequent cold snaps and heat waves for which they were heavily maladapted. Our results highlight the importance of considering evolutionary constraints when predicting population responses to climate change, and suggest that the multifaceted nature of thermal change may doom many species to extinction.