Lizards on the borders: source and patterns of colonization of an opportunistic reptile, Podarcis siculus, on the remote island of Pantelleria (Italy) depicted by mtDNA phylogeography and dorsal pattern

Understanding patterns and modalities of species’ colonization in insular ecosystems is a major goal of biogeography and may be key to decision makers, in terms of e.g., management and conservation. In this paper, we assess source and patterns of colonization of an opportunistic reptile, Podarcis siculus, on the remote island of Pantelleria (Italy), following a multidisciplinary approach combining molecular phylogeography and dorsal pattern analyses. We analyzed the mitochondrial gene cytochrome b (cytb) from 13 lizards and we assessed the frequency of the dorsal pattern phenotypes observing 188 basking lizards from eight localities throughout the island. The parsimony network revealed that haplotypes from Pantelleria belong to a haplogroup characteristic of western Sicily with the most common haplotype from Pantelleria being also found in three Sicilian localities. Unlike other Italian island populations, the dorsal pattern is highly conserved on Pantelleria, as a high percent of the observed individuals show the pattern also found in the hypothesized source area in western Sicily. In conclusion, our results are compatible with an allochthonous origin of the P. siculus population of Pantelleria Island. Thus, the species would need no population monitoring programme for its conservation on the island.