Talk, 8th BayCEER Workshop 2016, NW III: 2016-10-13
Introduction Climate and topography are among the most fundamental drivers of plant diversity but their relevance change across scales. High elevation islands offer a diverse setting of climatic and topographic conditions (so-called climatic mini-continents), enabling us to study the influence of both factors on spatial patterns of endemism. Once the spatial drivers of endemism are understood, we can use this knowledge to assess the vulnerability of single-island endemics (SIEs) to climate change. Material and Methods On the landscape scale of a single island, we use La Palma (Canary Islands) to test the relative importance of climate and topography on the spatial pattern of plant endemism using a large number of plots (n = 890). Also, we couple this spatial data with species distribution modeling techniques to determine how threatened SIEs are by ongoing climate change. Results Surprisingly, the relative importance of climate strongly differs depending on which response variables we focus on, i.e. endemic richness (a measure of biodiversity) or speciation-related endemicity (percentage of endemics). Small-scale topography best predicts endemic richness, while meso-scale climatic conditions are most important for endemicity. Coastal systems will lose almost all their SIEs due to upward shifts during climate change, while high elevation SIEs have the highest probability of extinction. Conclusions Hotspots of endemic richness in topographic complex regions are likely a combined result of evolutionary processes and small-scale human activities, while specialization and large-scale isolation effects likely drive hotspots of endemicity. The spatial incongruence in hotspots of endemic richness and endemicity emphasizes the need for an integrated conservation approach acknowledging different diversity measures to protect the complete spectrum of diversity. Climate change is a serious threat to island endemism and might have consequences for global biodiversity.