Interactive effects of experimental heating rates, ontogeny and body mass on the upper thermal limits of anuran larvae

Publication date: Available online 22 March 2019Source: Journal of Thermal BiologyAuthor(s): Gustavo A. Agudelo-Cantero, Carlos A. NavasAbstractBiological and methodological factors influence the upper thermal limits (UTL) of ectothermic animals, but most factors have been studied independently. Few studies have integrated variables, so our understanding about sources of UTL variation remains fragmentary. Thereby, we investigated synergic effects of experimental protocols (heating rates, ΔTs) and biological factors (ontogeny and body mass) on the UTL on the larvae of two anuran species (Physalaemus nattereri and Boana pardalis), specifically their Critical Thermal Maximum (CTmax). The species displayed slightly different responses to ΔTs: In B. pardalis tadpoles both average and variance of CTmax increased at a fastest ΔT, the same response happened in P. nattereri tadpoles at slow and moderate ΔTs. Also, the CTmax of P. nattereri declined at the end of metamorphosis independently of ΔT, but tadpoles at all developmental stages still displayed higher heat tolerance at the slow ΔT. Finally, we detected small, synergic effects of body mass and ΔTs on the CTmax of both species. In small B. pardalis tadpoles and premetamorphic P. nattereri tadpoles, body mass had a positive effect on CTmax, but only at slow and moderate ΔTs, probably indicating physiological responses. A similar trend was observed in large B. pardalis tadpoles at the fast ΔT, but this result is likely to...

Source: Journal of Thermal Biology - March 22, 2019 Category: Biology Source Type: research