Phylogeography of the ocellated skink Chalcides ocellatus (Squamata, Scincidae), with the use of mtDNA sequences: a hitch-hiker's guide to the Mediterranean.

We analyze geographic genetic variation in C. ocellatus to evaluate the influences of major climatic, paleogeographic and anthropogenic factors in its biogeographic history. Ninety four specimens from 61 populations were collected across all of its geographical range and analyzed based on partial mitochondrial sequences (cyt b, 12S, and ND1). Our results demonstrate that an ancestral form of C. ocellatus, which expanded in northwestern Africa at the end of Miocene, diverged in at least three separate evolutionary lineages approximately 4.57Ma: C. humilis spread south of the Sahara, while the other two (C. ocellatus sensu stricto) were restricted in the coastal North African region. The complicated history of the ocellated skink is a result of multiple vicariant phenomena followed by multiple active or passive dispersals. The Messinian salinity crisis and the re-flooding of the Mediterranean basin, the climatic transition from Middle to Upper Pliocene, and the hyperarid phase of the Sahara, affected the distribution and diversification of C. ocellatus, while in historical times it was introduced in the central Mediterranean islands and eastern Mediterranean region from Tunisia and Cyrenaica, respectively.

Mitochondrial DNA reveals the genealogical history of the snake-eyed lizards (Ophisops elegans and O. occidentalis) (Sauria: Lacertidae).

The snake-eyed lizards of the genus Ophisops (Lacertidae) have been through a series of taxonomical revisions, but still their phylogenetic relationships remain uncertain. In the present study we estimate the phylogeographic structure of O. elegans across its distributional range and we evaluate the relationships between O. elegans and the sympatric, in North Africa, species O. occidentalis, using partial mtDNA sequences (16S rRNA, COI, and cyt b). All phylogenetic analyses produced topologically identical trees where extant populations of O. elegans and O. occidentalis were found polyphyletic. Taking into account all the potential causes of polyphyly (introgressive hybridization, incomplete lineage sorting, and imperfect taxonomy) we suggest the inaccurate taxonomy as the most likely explanation for the observed pattern. Our results stress the need for re-evaluation of the current taxonomical status of these species and their subspecies. Furthermore, our biogeographic analyses and the estimated time of divergences suggest a late Miocene diversification within these species, where the present distribution of O. elegans and O. occidentalis was the result of several dispersal and vicariant events, which are associated with climatic oscillations (the late Miocene aridification of Asia and northern Africa) and paleogeographic barriers of late Miocene and Pliocene period.