Climate-induced range contraction in the Malagasy endemic plant genera Mediusella and Xerochlamys (Sarcolaenaceae)

Background and aims – Climate change imposes new challenges on biodiversity conservation, especially in tropical areas where anthropogenic pressures have already increased the vulnerability of many species. New conservation strategies are needed to anticipate the impacts of future climate change and species distribution modeling remains the most useful approach in predicting these impacts and in assisting conservation planning. The objectives of this study were to develop species distribution models for threatened endemic plant species of Madagascar and to assess the impacts of climate change on the species distributions. Methods – Ten species belonging to the genera Mediusella and Xerochlamys of Madagascar's endemic plant family Sarcolaenaceae were included in this study. Potential distribution models using 19 climatic variables were developed for the ten species and projected onto the present and future to evaluate the potential distribution of each species. Future distributions of these species were predicted for 2050 using three general circulation models and two climate scenarios. We also assessed the patterns of range shifts by comparing present and future distributions under the different models and scenarios. Key results – Most species were predicted to undergo major range contraction as a result of climate change. Species in the Central High Plateau of Madagascar were predicted to experience the highest habitat loss, with narrow-range species being the most sensitive. Southward migration was predicted for species distributed in the northwest, whereas upland migration was predicted for some central species. Conclusions – Future climate change will drastically affect the distribution of our target species, seven of which will experience major range contraction by 2050. Among these, threatened endemic species will face higher risk of extinction due to habitat loss. Range expansion was also predicted for two species. In any case, species' adaptation to a changing climate may not happen soon enough, emphasizing the need to strengthen current conservation efforts, especially in areas where species are most likely to persist.