Meeting Abstract

35.6  Thursday, Jan. 5  Responses of species to climate change: the role of thermal adaptation of thermal reaction norms SEARS, Michael W*; ANGILLETTA, Michael J; BUCKLEY, Lauren B; Bryn Mawr College; Arizona State University; University of North Carolina-Chapel Hill msears@brynmawr.edu

Understanding the responses of organisms to changing climates is one of the more pressing questions for ecologists today. Over the past century, global climates have warmed and models predict continued warming into the near future. Given the thermal sensitivities of numerous physiological traits, the fitnesses of organisms will likely be impacted by these climatic shifts. In response, organisms might shift their geographic ranges by tracking climates to which their physiological processes are adapted. Here, we examined how locally adapted thermal reaction norms (TRMs) might contribute to future shifts in geographical range. Using 50 years of historical climate data, we modeled the optimal TRMs for energy assimilation for populations that ranged over a broad latitudinal gradient in North America. TRMs were modeled with and without the inclusion of a thermodynamic effect (i.e., 'hotter is better'). We then estimated the fitness consequences of TRMs by performing virtual reciprocal transplants for all populations along the gradient. Resultant TRMs varied in both their optima and breadth in response to local climate. Generally, optima were correlated with average temperatures for a location and more variable climates produced broader TRMs. If a thermodynamic effect was included in the optimization, TRMs were generally broader with warmer optima. The resultant fitnesses of adapted genotypes across latitudes were enhanced both by temporal variation in temperatures at their locations of origin and by the inclusion of the thermodynamic effect. Our results indicate that the predicted negative effects of local adaptation on responses to climate change might be less pronounced if historical climate series and the thermodynamic effect are considered.