Insights into the introduction history and population genetic dynamics of the Argentine black-and-white tegu (Salvator merianae) in Florida

Invasive species are a major threat to global biodiversity. The US state of Florida is especially susceptible to the spread of exotic reptiles due to its subtropical climate, disturbed habitats, and robust pet trade. The Argentine black-and-white tegu (Salvator merianae) is a large, omnivorous lizard currently established in two different regions of Southern Florida. These two populations pose potential threats to sensitive ground nesting species such as gopher tortoises, American crocodiles, and migratory birds. At present, the introduction histories of these populations and the degree to which they are connected by gene flow are largely unknown. To address these issues, we genotyped S. merianae from Hillsborough and Miami-Dade Counties at ten microsatellite loci to assess intrapopulation genetic diversity, the degree of gene flow between populations, and compare the plausibilities of several potential introduction scenarios. Our results indicate that both populations have low genetic diversity [mean number of effective alleles across loci in both populations = 2.09 and are highly differentiated from each other (GST = 0.170; G″ST = 0.545)]. In addition, our results suggest that these populations underwent a bottleneck event prior to their divergence. We discuss what our results suggest about the histories of Florida’s invasive tegu populations, as well as how they inform ongoing management strategies.