Meeting Abstract

P3.121  Saturday, Jan. 5  Life in the Big City: Thermal Tolerance of Isopods to Urban Heat Islands COOPER, B.S.; WILLIAMS, B.H.*; ANGILLETTA, M..J.; Indiana State University, Terre Haute; Indiana State University, Terre Haute; Indiana State University, Terre Haute bwilliams27@mymail.indstate.edu

Urbanization has led to rapid heating of local environments, potentially creating new selective pressures for organisms that span urban-rural gradients. Previous studies have shown that some urban ectotherms tolerate heat better than their rural conspecifics. Recent advances in remote sensing have generated detailed maps of surface temperatures, which enable us to sample organisms on fine scales within urban heat islands. Using a thermal map of Indianapolis�the twelfth largest city in the United States�we sampled isopods (Armadillidium vulgare) from hot and cold sites within this city. Based on theory, we expected that isopods from hot sites would tolerate heat better and cold worse than isopods from cold sites. We used measures of knock-down times and chill-coma recovery to compare thermal tolerances of isopods from hot and cold sites. Contrary to our expectations, isopods from hot and cold sites took similar time to knockdown at 41�C and recover from exposure to 0�C. These results suggest several hypotheses, including that (i) remote sensing misrepresents the temperature of land surface, (ii) animals avoid urban heat through microhabitat selection, or (iii) gene flow among sites swamps the effect of selection. Validation of thermal maps with data loggers could eliminate potential artifacts of remote sensing and enable us to focus on biological explanations.