Meeting Abstract

S4-4  Friday, Jan. 6 09:00 - 09:30  The impact of temperature variation on physiology and distributions of tropical and temperate ectotherms SHELDON, K.S.; University of Tennessee, Knoxville ksheldon@utk.edu http://www.biogeographyresearch.org/

Differences in environmental temperatures can influence organismal physiology and biogeography, with large consequences for ecology, evolution and our understanding of the impacts of climate warming. Based on the seasonality hypothesis, smaller annual temperature variation in the tropics should result in reduced thermal tolerance, dispersal capacity, and elevational range sizes of tropical species compared with temperate species. Using beetles and Liolaemus lizards separated by latitude, I explored links between seasonality in temperature, physiology, and elevational range size. Thermal tolerance and elevational range size of beetles increased with increasing annual seasonality. Realized seasonality – the temperature variation restricted to the months that species are active – was a better predictor of both thermal tolerance and elevational range size of beetles than was annual seasonality. Additionally, beetles with narrower thermal tolerance had smaller elevational ranges. In Liolaemus lizards, annual seasonality was a good predictor of elevational range size. However, contrary to the seasonality hypothesis, thermal tolerance of adult Liolaemus was not a good predictor of elevational range size. In the case of Liolaemus lizards, temperature effects on reproduction and ontogeny may play a larger role in setting elevational distributions than the thermal tolerance of adults. These results support a mechanistic framework that links variation in temperature to the physiology and distributions of tropical and temperate ectotherms.