Modeling current and future distribution of invasive tegu lizards along geopolitical boundaries in the contiguous United States: Implications for invasion threat

• For the contiguous United States (CONUS), we conducted a quantitative, state-by-state comparison of how habitat suitability is likely to change under two plausible warming scenarios (+2° C and + 4° C) for three species of invasive tegus: black and white tegus ( Salvator merianae ), red tegus ( S. rufescens ), and gold tegus ( Tupinambis teguixin ). • Under current climate conditions, one or more invasive tegu species have the potential to occupy most ecoregions in the CONUS. Suitable habitat increases by 11% for black and white tegus, 31% for red tegus, and 466% for gold tegus (although the absolute amount of suitable habitat for gold tegus remains small) under a 4° C warming scenario. • For black and white tegus, parts of Florida where the species has already established become less suitable, while suitability increases in this region for red and gold tegus. • Our analysis provides proactive information for wildlife managers along geopolitical boundaries which can serve as a tool to prevent the establishment and spread of tegus across the CONUS. Historically, constrained temperature ranges limited the spread of invasive herpetofauna into temperate climates, but climate change is predicted to facilitate broader distributions. There are three species of tegu lizards native to South America and available in the pet trade that have a high risk of invasion and deleterious impacts to native ecosystems in the United States (US). There are four populations of the black and white tegu ( Salvator merianae ) in Florida and sightings as far north as North Carolina and west as California. Red tegus ( S. rufescens ) have been observed in Florida, and there is an established population of gold tegus ( Tupinambis teguixin ) in Florida. We updated previous distribution models for the contiguous United States (CONUS) that used occurrence points from their native range in South America to evaluate potential changes given current and future climate scenarios (+2°C and +4°C warming). Under current climate conditions, one or more tegu species have the potential to occupy most ecoregions in the CONUS. Under a +4 °C warming scenario, suitable habitat increases by 11% for S. merianae , 31% for S. rufescens . The proportion of suitable habitat for T. teguixin was small under all scenarios, but increased from 0.0003 to 0.0017. For S. merianae , parts of Florida become less suitable, while suitability increases in this region for the other two species. Additionally, much of the western US is projected to be suitable for S. rufescens . Our case study underscores the potential for climate change to compound invasion threats that could outpace effective managerial responses.