Molecular phylogeny of the Greek legless skink Ophiomorus punctatissimus (Squamata: Scincidae): the impact of the mid-Aegean trench in its phylogeography.

Sequence data derived from three mitochondrial markers (cytochrome b, 16S rRNA and 12S rRNA genes) were used to infer the evolutionary history of several insular and mainland populations of the Greek legless skink (Ophiomorus punctatissimus), covering most of its distributional range. All phylogenetic analyses produced topologically identical trees that revealed a well-resolved phylogeny. These trees support two O. punctatissimus clades, which are geographically separated (west and east of the mid-Aegean trench). The assumption of a clock-like evolution could not be rejected, and thus a local clock was calibrated for the O. punctatissimus lineages. The non-overlapping geographic distributions of the major clades suggest a spatial and temporal sequence of diversification that coincides with paleogeographic separations during the geological history of the Aegean region. It seems that O. punctatissimus is an old eastern Mediterranean species that has been differentiating in this region at least from middle Miocene. It is possible that the ancestral form of O. punctatissimus invaded the Aegean region from Anatolia before the complete formation of the mid-Aegean trench, when the Aegean was still a uniform landmass, while other vicariant events have led to its present distribution.