Non-native (invasive) species offer a unique opportunity to study the geographic distribution and range limits of species, wherein the evolutionary change driven by interspecific interactions between native and non-native closely related species is a key component. The red-eared slider turtle, Trachemys scripta elegans (TSE), has been introduced and successfully established worldwide. It can coexist with its native congeners T. cataspila, T. venusta and T. taylori in Mexico. We performed comprehensive fieldwork, executed a battery of genetic analyses and applied a novel species distribution modeling approach to evaluate their historical lineage relationships and contemporary population genetic patterns. Our findings support the historical common ancestry between native TSE and non-native (TSE_alien), while also highlighting the genetic differentiation of the exotic lineage. Genetic patterns are associated with their range size/endemism gradient, the microendemic T. taylori showed significant reduced genetic diversity and high differentiation, whereas TSE_alien showed the highest diversity and signals of population size expansion. Counter to our expectations, lower naturally occurring distribution overlap and little admixture patterns were found between TSE and its congeners, exhibiting reduced gene flow and clear genetic separation across neighboring species despite having zones of contact. We demonstrate that these native Trachemys species have distinct climatic niche suitability, likely preventing establishment of and displacement by the TSE_alien. Moreover, we found major niche overlap between TSE_alien and native species worldwide, supporting our prediction that sites with closer ecological optima to the invasive species have higher establishment risk than those that are closer to the niche-center of the native species.

The dataset includes 261 samples, comprising individuals from the field, traded turtles of unknown origin, and museum samples, including: 69 turtle individuals of Trachemys venusta, 13 T. cataspila, 12 T. taylori, 128 non-native Trachemys scripta elegans TSE_alien and 39 native TSE (see Table S1 from the Supporting Information provided with the Mol Ecol Publication).

We amplified 15 polymorphic microsatellite loci for 256 individuals (genepop file), and obtained GBS data for a final dataset after filtering including 160 samples (vcf file).

The final GBS data file has an average number of loci/sample = 55,982, coverage = 16x, and 63,385 SNPs.