Transoceanic genetic similarities of kelp‐associated sea slug populations: long‐distance dispersal via rafting?

A groundbreaking study reveals that sea slug populations of the genus Onchidella, previously thought to be distinct species, are genetically interconnected across vast distances in the Southern Hemisphere. The research, conducted on cool-temperate and subantarctic coasts including New Zealand's subantarctic islands, southern Chile, and the Falkland Islands, challenges traditional taxonomic classifications by demonstrating widespread genetic similarity among these slugs. This connectivity is attributed to passive rafting facilitated by buoyant bull-kelp (Durvillaea) and driven by circumpolar ocean currents. The study employed mitochondrial DNA sequences and amplified fragment length polymorphisms (AFLPs) to analyze population structuring, uncovering substantial differentiation in mainland New Zealand populations while highlighting shared haplotypes among distant subantarctic samples. These findings suggest recent common ancestry and long-distance dispersal mechanisms for these ecologically significant marine organisms.

Cumming, R. A., Nikula, R., Spencer, H. G., & Waters, J. M. (2014). Transoceanic genetic similarities of kelp‐associated sea slug populations: long‐distance dispersal via rafting? Journal of Biogeography, 41(12), 2357–2370. Portico. https://doi.org/10.1111/jbi.12376