Molecular analysis of recently introduced populations of the Italian wall lizard (Podarcis siculus)

In recent decades, many reptile species have been introduced outside their native ranges, either accidentally through the transportation of goods and materials (e.g., plants, construction materials), but also intentionally through the pet trade. As a paradigmatic example, the Italian wall lizard, Podarcis siculus, native to the Italian Peninsula, Sicily and the north Adriatic coast, has been introduced in several nearby islands since historical times (Corsica, Sardinia, Menorca). Besides these regions, scattered populations were later reported from the Iberian Peninsula, France, Switzerland, Turkey, Greece, the United Kingdom and North America. Here, we provide molecular evidence regarding the introduction and origin of P. siculus in six new populations outside its native range: Romania (Bucharest and Alba Iulia), inland Croatia (Zagreb and Karlovac), Italy (Lampedusa Island) and Azerbaijan (Baku). Phylogenetic analysis suggests that the Alba Iulia (Romania) population originated from a single clade (Tuscany), while the population from Azerbaijan is admixed including two distinct clades, one similar to those found in Sicily and the other present across the Tuscany clade. Samples from Bucharest also have admixed origins in Tuscany and the Adriatic clades. Less surprisingly, samples from Zagreb and Karlovac are included in the Adriatic clade while those from Lampedusa originated from Sicily. Overall, our results further demonstrate that P. siculus is able to establish outside of its native range even under different climatic conditions, not particularly from specific clades or source areas. Also, for the first time in this species, our results indicate that repeated human introductions promote lineage admixture and enhance their invasive potential.