Origin of introduced Italian wall lizards, Podarcis siculus (Rafinesque-Schmaltz, 1810) (Squamata: Lacertidae), in North America

Invasive species are one of the main causes of biodiversity loss worldwide. As introduced, populations may increase in abundance and expand geographical range, so does the potential for negative impacts on native communities. As such, it is necessary to understand the processes driving range expansion, before a species becomes established in new areas. Through an investigation into capacity for population growth and range expansion of introduced populations of a non-native lizard, we aimed to demonstrate how multi-scale factors influence spatial spread, population growth, and invasion potential in introduced species. The Italian Wall Lizard (Podarcis siculus) was introduced multiple times to the United States with extant populations in California, Kansas, New Jersey, and New York. Recently, a single specimen was discovered in British Columbia, Canada, and unstudied populations are on Orcas Island and Missouri (USA). We used phylogenetic analysis of mtDNA sequences (cytb gene) of individuals sampled from these introduced populations and across the native range to identify potential source populations. Our phylogenetic analysis result with documentation of the introductions revealed that the Canadian individual is derived from the Tuscany clade (together with samples from Kansas and New York). The New Jersey population is likely from the Adriatic clade and the Californian one from Sicily. The Orcas Island and Missouri populations still require study. Consequently, humans are key drivers of the distribution of alien reptiles in North America, but the distributions are determined by a complex interplay between human activities, geographic factors and species features. Genetic evidence is essential for reliable biogeographic assessment of invasive species, particularly in systems with a long history of human influence.

Automated summary

Invasive species are a major cause of biodiversity loss worldwide. By studying the population growth and geographical range expansion of non-native lizard populations, we can understand the factors influencing their spatial spread, population growth, and invasion potential. The distribution of alien reptiles in North America is determined by a complex interplay between human activities, geographic factors, and species features. Genetic evidence is crucial for reliable biogeographic assessment of invasive species.