The potential impacts of climate change on mammal functional groups at regional scale: the case of Iranian terrestrial mammals

The negative impacts of climate change on mammals have been largely based on assessments of total species assemblages or individual species at broad scales. Here, we evaluate how the predicted magnitude and velocity of climate change in the arid region of southwest Asia might affect regional functional groups of terrestrial mammals. Location: Iran We gathered data from 186 species to map diversity hotspots of 12 functional groups, threatened species richness, and total species richness. We mapped areas with high risk of exposure to extreme drying and warming events and calculated the velocity of climate change by using precipitation and temperature data from current and future periods. We then quantified the exposure of these hotspots to extreme changes in magnitude and velocity. Hotspots of functional groups, threatened species, and species richness were most exposed to precipitation decline in current and future scenarios (average of 17.9% and 29.9% respectively), compared to temperature rise. While most hotspots are found in mountains, hotspots located in lowlands were more exposed to extreme drying; particularly for carnivore, desert and large-bodied functional groups, as well as threatened species. These patterns remained intact when we considered only hotspots covered by existing protected areas. The impacts of velocity also varied significantly among functional groups, with highest levels for carnivore, large-bodied and specialist groups and threatened species. We show that climate change does not equally impact all species within a community and that vulnerability to these changes differed between functional groups. We found that the areas with the highest risk of exposure to extreme climates are located in lowlands and not in mountains. We found that extreme drying, rather than warming, is the major threat to regional mammal diversity in this arid region, particularly for large-bodied and threatened species.