Mitochondrial DNA sequence analysis reveals multiple Pleistocene glacial refugia for Podarcis muralis (Laurenti, 1768) in the Italian Peninsula

The genetic variability of the wall lizard, Podarcis muralis, was analysed in that part of its range regarded as its area of origin and also its expansion centre. The analysis was performed on partial cytochrome b sequences (405 bp) of 117 specimens representing 31 sampling locations from southern, central and northern Italy. The results of this study revealed 30 haplotypes in the Italian sample belonging to three main genetic lineages. The genetic divergence among haplotypes ranged from 0.2 to 6.6%, whereas the estimation of divergence times among mtDNA lineages highlighted a complex pattern of genetic differentiation with both Pleistocene and Pliocene divergences (3.2-0.7 Ma). These results put in evidence the role played by the pre-Pleistocene and Pleistocene palaeogeographic and palaeoclimatic events in shaping the genetic diversity of the wall lizard in Italy and confirm the role of this peninsula as glacial refuge. In addition, AMOVA analysis revealed the presence of geographically structured clades indicating the occurrence of multiple glacial refugia in Italy, thus supporting a refugia-within-refugia scenario for the wall lizard in Italy. Finally, the results of this study seem to indicate a lack of congruence between the four morphological subspecies currently recognised in the Italian Peninsula and the main genetic lineages detected.