Rare species perform worse than widespread species under changed climate

Predicting how species, particularly rare and endangered ones, will react to climate change is a major current challenge in ecology. Rare species are expected to have a narrower niche width than more widespread species. However, we know little whether rare species are also less able to cope with new climatic conditions. To simulate climate change, we transplanted 35 plant species varying in rarity to five botanical gardens in Switzerland, differing in altitude. For each species we calculated the difference in climate between their natural habitats and the novel climate of the respective botanical garden. We found that species with a small range size had generally lower survival and biomass production than widespread species (57% higher biomass and 10% higher survival in species with a range size of 390 grid cells occupied than in species with two grid cells occupied). Moreover, rare plant species survived less when the amount of precipitation differed more from the one in their natural range, indicating a higher susceptibility to climate change. Widespread species, in contrast, survived equally well under all climates and even increased their biomass under wetter or drier conditions. Our study indicates that rarer species are less able to cope with changes in climate compared to more widespread ones, which might even benefit from these changes. This indicates that already rare and endangered plant species might suffer strongly from future climate change.