Phylogeography of the Italian wall lizard, Podarcis sicula, as revealed by mitochondrial DNA sequences.

Abstract

In a phylogeographical survey of the Italian wall lizard, Podarcis sicula, DNA sequence variation along an 887-bp segment of the cytochrome b gene was examined in 96 specimens from 86 localities covering the distribution range of the species. In addition, parts of the 12S rRNA and 16S rRNA genes from 12 selected specimens as representatives of more divergent cytochrome b haploclades were sequenced (together about 950 bp). Six phylogeographical main groups were found, three representing samples of the nominate subspecies Podarcis sicula sicula and closely related subspecies and the other three comprising Podarcis sicula campestris as well as all subspecies described from northern and eastern Adriatic islands. In southern Italy a population group with morphological characters of P. s. sicula but with the mitochondrial DNA features of P. s. campestris was detected indicating a probably recent hybridization zone. The present distribution patterns were interpreted as the consequence of natural events like retreats to glacial refuges and postglacial area expansions, but also as the results of multiple introductions by man.