Talk, 42nd Annual Meeting of the Ecological Society of Germany, Austria and Switzerland, Lüneburg: 2012-09-10 - 2012-09-14
Abstract:
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, however, is a non-trivial task, as elevation as an indicator for habitat diversity and island age as an indicator for the time available for diversification are often correlated. In addition, the geographic distance to source ecosystems might differ among habitats, which could lead to habitat-specific reduction of species immigration, niche occupation and diversification. We used the percentage of single island endemic species (pSIE) as an indicator for diversification on islands. 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. Consequently these high elevation ecosystems on island or island like mountains typically support a higher degree of endemic species than their low elevation counterpart. 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.