Climatic debts for global amphibians: Who, where and why?

Abstract

Biodiversity usually needs time to respond to changes in external forces such as climate and landscape, making the assessment of biodiversity crises more complex and challenging. The phenomena of delay in species tracking suitable climate under changing environments can be described as climate debt. Amphibians are the most dispersal-limited vertebrate group with extreme sensitivity to climatic changes; thus, they are more vulnerable to accumulating climatic debts. Furthermore, different amphibians usually have different habitat requirements and preferences; thus, their exposure to climatic changes can vary. Here, we conducted one of the most comprehensive assessments on the features of current and future climatic debts for amphibians, for different orders and families, and over different geographic regions of the world. Our study showed that global amphibians tended to accumulate higher climatic debts in different regions when the climate was further warmed up from the present to the future periods. At the taxonomic level, it was found that families like Pelodryadidae, Mantellidae, Limnodynastidae, Dicroglossidae, Bufonidae, and Ptychadenidae were major contributors to climatic debts. For IUCN red list categories, the least-concern species nevertheless contributed the largest proportion of climatic debts. As a comparison, at the spatial scale, biomes such as temperate broadleaf and mixed forests, boreal forests/Taiga, temperate conifer forests and tundra experienced dramatic increases in debt from the present to the future. Tropical and subtropical forests constantly contribute major climatic debts. For zoogeographic regions, debt increased in Palearctic and Sino-Japanese regions over time. Landscape heterogeneity was the principal predictor of spatial climatic debt patterns for amphibians but not life-history traits and phylogenetic relationships of the taxa. Conclusively, this study can provide insights into the global priority area and species needed for conserving amphibians under different climate change scenarios.