Inter- and intra-island speciation and their morphological and ecological correlates in Aeonium (Crassulaceae), a species-rich Macaronesian radiation.

Our findings illustrate the importance of both inter- and intra-island speciation, of which the latter potentially is sympatric speciation. Speciation on the same island entailed significantly higher levels of morphological divergence compared to inter-island speciation, but ecological divergence was not significantly different. Longer periods of shared island habitation resulted in the evolution of a higher degree of spatial separation and stronger reproductive barriers.