Multiple introductions and successful establishment of the invasive land snail Rumina decollata

Biological invasions are a major component of global change and biodiversity loss. Rumina decollata, a Mediterranean land snail, has been introduced beyond its native range through human-mediated dispersal and is now widely distributed across much of Argentina. Here, we investigated the origin of Argentine populations using mitochondrial COI sequences from Argentine populations spanning a broad latitudinal and environmental gradient. All analysed populations clustered within the mitochondrial lineage previously identified as invasive worldwide. A single haplotype identical to sequences from Spain and Portugal dominated most Argentine populations, while two additional haplotypes matched lineages from Portugal and southern France, indicating multiple introduction events followed by extensive secondary spread. Despite low mitochondrial diversity, R. decollata has successfully colonised diverse environments, suggesting that reproductive traits such as self-fertilisation may have contributed to population persistence following introduction. In addition, body and sole colouration was variable and did not reliably diagnose the invasive clade. Our results highlight how repeated introductions and life-history traits interact to facilitate establishment and spread, even under strong demographic constraints.