Meeting Abstract

11.1  Saturday, Jan. 4 10:15  Climate sensitivity, thermal safety, and the importance of behavior across latitude and elevation SUNDAY, J.M.*; BATES, A.E.; KEARNEY, M.R.; COLWELL, R.K.; DULVY, N.K.; LONGINO, J.T.; HUEY, R.B.; Simon Fraser University; Institute for Marine and Antarctic Studies; University of Melbourne; University of Connecticut; Simon Fraser University; University of Utah; University of Washington sunday@sfu.ca

Thermal tolerance limits of terrestrial ectotherms often exceed experienced air temperatures, giving rise to an apparently high degree of thermal safety – or an excess of warm or cold thermal tolerance. Yet air temperatures can be wildly different from the realized body temperatures with which ectotherms must physiologically or behaviorally contend. Here, we compile a global dataset of thermal tolerance limits of ectotherms across both latitude and elevation, and compare these to operative temperatures (theoretically equilibrated body temperatures) during the warmest and coldest times of the year. We show that, contrary to previous findings, ectotherms do not have physiological thermal safety. Instead, behavioral retreat from the sun is required to avoid dangerous overheating during the warmest times, and this requirement is greatest at low latitudes and elevations. Likewise, retreats from cold exposure are frequently required for species living at temperate latitudes and in alpine habitats. Under climate warming, the availability of thermally-protective habitats, and the behavioral and energetic constraints to using these habitats, will be critical aspects of species vulnerability.