Characterizing metabolic responses of Eleutherodactylus frogs in Puerto Rico to different thermal treatments: implications for conservation.

Amphibians are increasingly vulnerable to extinction due to physiological stress induced by projected global warming and associated drying trends. Understanding the underlying mechanisms and consequences of these responses is crucial to developing effective conservation strategies. Puerto Rico hosts 15 endemic Eleutherodactylus frog species, which are particularly vulnerable to environmental changes due to poor vagility and narrow thermotolerance. In this study, we report routine metabolic rates (RMRs) of four species in response to four temperature treatments (15, 20, 25 and 30°C) at two temporal scales (24 and 72 hours) using indirect calorimetry. Results indicated that three species exhibited increased RMR with rising temperatures. The RMR at 25°C for E. wightmanae was spurious, and it was the only species that did not survive at 30°C. The Arrhenius breakpoint analysis indicated that E. juanariveroi RMR decreased between 25 and 30°C. In contrast, E. antillensis and E. coqui RMR increased with increasing assay temperatures. We discuss how diel metabolic demands decrease the scope at both thermal extremes for E. antillensis and E. coqui, and how habitat temperature may impinge energetic challenges to those coping with documented warming trends, such as E. wightmanae.