Slowing down: A macroevolutionary approach to the hypometabolic strategies of amphibians

The ability to survive harsh environmental conditions has probably been a key factor in the evolutionary success of organisms that cannot migrate long distances, such as amphibians. Therefore, we expect that the presence of a hypometabolic strategy (HS; like aestivation or hibernation) to deal with severe climatic conditions, would be a plesiomorphic trait. Here we 1) inferred the ancestral state of a HS in amphibians, 2) analyzed if amphibians with a HS have larger distributional ranges, and 3) explored how a HS may affect amphibian assemblage resilience using multiple models of climate change. We highlight that more research is necessary as information was available for many different lineages but < 10% of the total amphibian species. Ancestral state reconstruction showed a relatively high probability for the presences of a HS in the most recent common ancestors of Anura (73.09 ± 13.73), Caudata (78.66 ± 12.30), and Gymnophiona (77.26 ± 14.74). Our climate analyses predict that tropical zones will have the greatest degree of climate change, despite having the lowest proportion of species with HS. Thus, tropical amphibian assemblages at low elevations or in tropical rainforests may be vulnerable to changes in climate. We found that species with a HS have significantly larger distribution ranges and most of those species are in the Least Concern IUCN category. It is likely that presence of HS as an ancestral state has been key for the evolutionary success in amphibians, and it will likely impact their future survival in the face of climate change.