Genetic diversity and connectivity of the invasive gastropod, Callinina georgiana (Caenogastropoda: Viviparidae) across a fragmented riverscape: a mitonuclear perspective

Aquatic Invasive Species (AIS) are a significant threat to global freshwater biodiversity. This study focuses on the banded mystery snail, Callinina georgiana, an invasive species in the Adirondack region of northern New York – an important section of the New York Great Lakes Basin. This project aims to explore the genetic connectivity of C. georgiana within its invasive range using a combination of mitochondrial and nuclear markers.

Sampling was conducted in the Raquette River and adjacent waterways, with a total of 229 snails collected from 16 distinct populations distributed across eight different waterbodies. Also included were two populations from the species’ native range in the southern United States. DNA was extracted, and a 710 bp fragment of the mtDNA marker COI and a 351 bp fragment of nuclear marker Histone-3 (H3) were amplified. Population genetic analyses including haplotype patterning, AMOVA and genetic diversity estimates, neutrality tests and tests for isolation by distance (IBD) were performed to assess connectivity patterns.

Results showed moderate to high levels of genetic admixture within the snail’s invasive range as indicated by the lack of geographic patterning of haplotypes and low to moderate levels of genetic differentiation across multiple sites. Demographic analyses combined with high numbers of private haplotypes indicate population expansion. Interestingly, a case of mitonuclear discordance was detected for native and invasive populations as evident by incongruent haplotype patterns for the COI and H3 markers.

Callinina georgiana exhibits a high level of genetic connectivity in its invasive range. The presence of dams does not significantly affect gene flow, indicating that anthropogenic activities, such as boat traffic might be key in dispersing the snails across this fragmented freshwater system.

This study offers new insights into the dispersal and genetic structure of an invasive freshwater snail. It highlights the importance of considering anthropogenic factors when confronting complex patterns of genetic diversity. The findings are significant for biodiversity conservation and provide a basis for developing strategies to manage and contain the spread of AIS like C. georgiana, especially in regions with high human activity.