Comparative thermal tolerances in tropical and temperate tadpole communities. Can tropical tadpoles take the heat?

DUARTE, H.; TEJEDO, M.; KATZENBERGER, M; 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

The impact of climate change on terrestrial ectotherms is predicted to be higher in tropical communities. Assuming upper thermal tolerances are homogeneous along a latitudinal gradient, their proximity to environmental temperatures suggests a higher vulnerability to extinction compared to temperate regions, where warming would actually be beneficial. In this communication we tested this prediction by collecting environmental temperatures and critical thermal maxima of two larval amphibian communities: a subtropical community from the Chaco, Argentina with high environmental temperatures ranging from 20ºC to 42ºC where we studied 18 species comprising five different amphibian families, and a temperate Iberian community with lower pond temperatures ranging from 5ºC to 34ºC with 8 species comprising six families. Results indicate that tropical tadpoles species can tolerate much higher temperatures (average species CTmax = 42,3 °C, range 40,6°C - 44,7°C) than temperate species (CTmax = 37.9 °C, range 36,6°C - 39,7°C). These results suggest that latitudinal differences exist in tadpole thermal tolerances, considering that some lineages are shared between both amphibian communities (Bufonidae and Hylidae), thus suggesting adaptive evolutionary divergence within clades. Also, it is clear that tropical species are closer to their physiological limit than temperate ones and therefore at higher risk of extinction to global warming.