Human introductions create opportunities for intra-specific hybridization in an alien lizard

Introduction of individuals from multiple sources could create opportunities for hybridization between previously isolated lineages, which may impact on the invasion process. Identifying the phylogeographic origin of introduced populations is therefore an important task to further test the causes and consequences of human-mediated translocations. The common wall lizard (Podarcis muralis) shows a strong phylogeographic structure as a result of past isolation in glacial refugia, but it has also been commonly introduced outside of its native range. Here we analysed 655 base pairs (bp) of the cytochrome b sequence from 507 individuals from 23 introduced populations of P. muralis in England. We identified 12 unique haplotypes in the introduced populations that were nested into five native geographically distinct clades with genetic divergences ranging from 2. 1 to 5. 7 %. Multiple clade origin was common within populations, with a maximum of three different haplotype clades being represented within a single population. The genetic data are consistent with a scenario whereby initial establishment was a result of translocation of animals from their native range, whereas more recent establishment (i. e. since the mid-1980s) is the result of translocations of animals from previously established non-native populations. However, this requires further study. Overall, our results show that human introductions have created substantial opportunities for hybridization between genetically and phenotypically distinct lineages, which may have important consequences for the establishment success and long-term viability of introduced wall lizard populations. © 2012 Springer Science+Business Media Dordrecht.