Thermal Tolerances in Tadpoles of Three Species of Patagonian Anurans

Abstract

Anurans living along the Andes cordillera exploit several thermal environments that vary with altitude and latitude. Studies on moderate and high-elevation tropical species suggest co-adaptation between thermal ecology and thermal physiology. Our objective was to test whether this is the case for three Patagonian anuran species. We focused on larval stages and analyzed critical maximum and minimum temperatures granting survivorship. The species studied were Abodes gargola, Pleurodema bufoninum and Rhinella spinulosa papillosa. Alsodes gargola lives primarily in high-elevation lakes and montane streams, has long larval development and overwinters. In contrast, tadpoles of P. bufoninum and R. s. papillosa use marshes and lower elevation ponds, and develop in three months. Tadpoles of Abodes gargola tolerated experimental temperatures up to 32°C and those of the other two species lost the ability to move at temperatures near 38°C. Tadpoles of all species tolerated experimental exposure to 0°C for a limited period of time, but A. gargola had higher mortality rates when exposed to freezing than the other two species. These results are consistent with some traits of thermal ecology, exemplified by the higher thermal stability of the environments used by A. gargola. However, other factors such as physiological trade-offs may partially explain this pattern.