Vortrag, International Biogeography Society (IBS) 6th Biennial Meeting, Miami, USA: 09.01.2013 - 13.01.2013
Elevational gradients in species diversity are among the most fascinating patterns in biogeography. However, there is still a sever lacks in identifying causalities and processes that are responsible for those patterns. The degree of diversification on islands or island like mountains is suspected to be positively influenced by isolation, time and environmental heterogeneity. A differentiation of these influences is often hindered by a correlation among variables. We show, that elevation specific data on endemism can be used to disentangle different drivers of species diversity. Especially the percentage of single island endemic species can provide information on changes of diversification along elevational gradients. With data from different island systems (oceanic and continental) and at different resolutions (within islands and on entire archipelagos) we found evidence for an elevation-driven ecological isolation, that leads to distinctly higher diversification in high elevated ecosystems. The geographic distance to source ecosystems is larger for high elevation ecosystems in comparison to low elevation counterparts. Consequently these high elevation ecosystems on island or island like mountains support a higher degree of endemic species. High elevation ecosystems also pose a special opportunity when investigating the basic processes of island biogeography, as they are the part of an island that is fastest eroded in the ontogeny of an oceanic island. This leaves the highly specialised biota the least time to establish and move on to a newly emerging island within the archipelago.