Thermal tolerance of two desert anurans: Does geographical variables increase vulnerability?

Abstract

The rapid and continuous warming of our planet, driven by human activities, is accelerating, with the heating rate of the last decade surpassing that of the past 50 years.This has profoundly impacted the organisms, but its consequences for the future remain uncertain. We studied the elevational and latitudinal variation of the critical thermal maximum in two anuran species, which provides insights into species ecophysiological limits. Furthermore, we analyzed warming tolerance along the elavational and latitudinal gradient, evaluating both current and future environmental conditions under climate change scenarios proposed by the IPCC (2022) for 2100. Critical thermal maximum of the studied species changed in different ways in relation to geographical factors. Rhinella arenarum showed an increase in the critical thermal maximum with absolute latitude, this value was associated with the decrease in elevation at the site of maximum latitude. Contrarily, Pleurodema nebulosum showed no changes in the critical thermal maximum with elevation or latitude. On the other hand, the values of warming tolerance changed among the studied populations, with the least tolerant being those located at higher latitudes/lower elevations. This effect was observed because the microenvironmental temperatures behaved inversely in the latitudinal gradient, with southern environments being warmer than northern ones.