|Steinbauer, M; Irl, S; Beierkuhnlein, C: Elevation-driven ecological isolation promotes diversification on Mediterranean islands, Acta Oecologica, 47, 52-56 (2013)|
The percentage of single island neo-endemic species (an indicator for evolutionary diversification) was found to be independent of geographic distance to the continent in the case of the Aegean archipelago. It was concluded that speciation is independent of geographic isolation, while evolutionary processes are rather enhanced by habitat heterogeneity. An island’s maximum elevation was used as an indicator for habitat heterogeneity. In contrast, we argue that habitat heterogeneity (= habitat diversity, i.e. the richness in different habitats) may be positively related to biotic richness, but a positive effect on speciation is yet to be proven. For any other type of heterogeneity, we propose a precise wording, especially when assessing its effect on speciation processes.