Poster, IBS 2015 - 7th International Conference of the International Biogeography Society, University of Bayreuth: 08.01.2015 - 12.01.2015
Oceanic islands harbor a wide range of endemic species. However, within each island endemics can have strongly varying range sizes, some being highly range-restricted ‘specialists’ and others widespread ‘generalists’. In addition, specific traits (e.g. growth form, dispersal mode, N-fixing and succulence), which are connected to specific environmental conditions, might determine the range size of endemics. Also, it is not clear if small-ranged specialists or an agglomeration of generalists create hotspots of endemic richness (ER). Single-island endemics (SIEs), which evolved in situ under island conditions, will likely have different range sizes than archipelago endemics (AEs). We hypothesize the following: i) Environmental conditions and specific ecological traits determine the range size of endemics, ii) hotspots of ER result from the agglomeration of generalist species, and iii) SIEs have smaller ranges and are therefore more specialized than AEs. To test this, we use a spatially highly resolved dataset of endemic vascular plants and environmental data in 890 plots on La Palma, Canary Islands to relate various range size metrics to ER and environmental variables.