Niche diversification of Mediterranean and southwestern Asian tortoises.

BACKGROUND

Tortoises of the genus are widely distributed throughout the Mediterranean region and southwestern Asia. However, the evolutionary mechanisms of diversification in this genus are still poorly understood.

METHODS

In this study, we assessed the evolutionary patterns in the climate niches of five species and 11 subspecies of the genus using ecological niche models and evaluated the niche overlap based on species phylogenetic distances.

RESULTS

The ecological models indicated that most species differ in their climate niches, but show overlap, with gradual transitions at range boundaries. As expected, the ecological divergence among subspecies was lower than that among species. Evaluation of the phylogenetic signal indicated that climate niches have been weakly conserved, but sister species also show high evolutionary divergence.