Can Species Distributions Models Help to Design Conservation Strategies for Narrow-Ranged Species under Climate Change? A Case Study from Santolina Genus

Climate change is dramatically threatening biodiversity. Narrowly distributed species are especially exposed to extinction risk due to their narrow ecological niche. We used Species Distribution Models at fine spatial resolution (50 m) to investigate changes in the distribution of three range-restricted species of Santolina (Asteraceae) endemic to the Mediterranean Basin (S. decumbens, S. ligustica, S. pinnata). We assessed the future potential range under an optimistic and a pessimistic scenario, and analysed distribution change taking into account three different areas: the distributional range (calculated as convex hull), an area 5 km larger than the distributional range, and a buffer (1 km) around occurrences. Santolina ligustica is expected to dramatically reduce its range under both scenarios, S. decumbens is expected to increase its range under both scenarios and S. pinnata is expected to dramatically reduce its range under pessimistic scenario and to increase it under optimistic one. Moreover, under the optimistic scenario, S. ligustica and S. pinnata show a very high range loss in all areas but the range gain is major in the largest area than in the other two areas. This result suggests that, in the future, suitable areas will occur mainly outside of the current distributional range and that assisted colonization might be necessary to assure species survival. Differently the third species has a lower range loss and higher range gain within the distributional range and in the buffer around occurrences, suggesting the possibility of survival in microrefugia within its distributional range despite a wide reduction in suitable habitat. These results might help to design strategies for species conservation in face of future climate change.