Extinction risks of a Mediterranean neo-endemism complex of mountain vipers triggered by climate change.

Climate change is among the most important drivers of biodiversity decline through shift or shrinkage in suitable habitat of species. Mountain vipers of the genus Montivipera are under extreme risk from climate changes given their evolutionary history and geographic distribution. In this study, we divided all Montivipera species into three phylogenetic-geographic Montivipera clades (PGMC; Bornmuelleri, Raddei and Xanthina) and applied an ensemble ecological niche modelling (ENM) approach under different climatic scenarios to assess changes in projected suitable habitats of these species. Based on the predicted range losses, we assessed the projected extinction risk of the species relative to IUCN Red List Criteria. Our result revealed a strong decline in suitable habitats for all PGMCs (63.8%, 79.3% and 96.8% for Xanthina, Raddei and Bornmuelleri, respectively, by 2070 and under 8.5 RCP scenario) with patterns of altitudinal range shifts in response to projected climate change. We found that the mountains close to the Mediterranean Sea are exposed to the highest threats in the future (84.6 ± 9.1 percent range loss). We also revealed that disjunct populations of Montivipera will be additionally highly isolated and fragmented in the future. We argue that leveraging climate niche projections into the risk assessment provides the opportunity to implement IUCN criteria and better assess forthcoming extinction risks of species.