Comparative analysis of thermal performances curves in a tropical and temperate amphibian tadpoles communities. Are tropical taxa living on the edge?

KATZENBERGER, M; TEJEDO, M.; DUARTE, H.; MARANGONI, F.; BELTRAN, J. F.

Bialowieza, Poland

Workshop; Evolutionary and Physiological Adaptation to Climate Induced Environmental Changes; 2009

Mammal Research Institute, Polish Academy of Sciences

Amphibian physiological performance is highly affected by environmental thermal characteristics. With expected global warming, the ability to perform ecologically relevant functions may be compromised, affecting their general fitness. Assessing how a species performs at a range of temperatures will highlight its susceptibility to temperature changes and subsequently its risk of extinction. Tropical ectotherms are considered to be more vulnerable to warming than higher latitude species, because environmental temperatures are closer to their optimum. To verify this hypothesis, we analyzed the swimming performance of anuran larvae of nine species from a subtropical community at the Gran Chaco, Argentina (water temperature range: 20ºC - 42ºC) and seven species from a temperate community at the Iberian Peninsula (pond temperatures range: 5ºC - 34ºC), to obtain their specific thermal performance curves (TPCs). We found that Neotropical species have their maximal and optimal performance shifted towards higher temperatures. Some species tend to follow the ‘‘jack-of-all-temperatures’’ strategy (e.g. Pelobates cultripes, Pseudis paradoxa), and others have a well defined maximum peak of performance (e.g. Alytes cisternasii, Hypsiboas raniceps). Facing global warming, most tropical species are already operating very near or even above their physiological optimum and any increase in warming may have catastrophic consequences. Contrarily, temperate species, generally living in sub-optimum cooler environments, may in fact benefit or not be affected at all, especially those with wider breadth TPCs.