WHAT THE EVIDENCE SAYS
For two sympatric Phorcus topshells, short particle-tracking runs showed strong local retention and even 90-day simulations did not connect the western and eastern Mediterranean basins. Genomic structure supported low natural connectivity, while near-identical profiles between localities separated by more than 1,000 km—near major ports—were inconsistent with a simple coastal stepping-stone pattern and supported human-mediated dispersal.
WHY IT MATTERS / OUR READ
Connectivity models should include transport pathways created by people. Natural currents can imply strong isolation while ports and vessels create rare jumps that reorganize population structure and potentially move species or genotypes across barriers.
CAVEATS / UNCERTAINTY
Ship-mediated dispersal is inferred from the mismatch between natural-dispersal modeling, genomic similarity and port geography rather than observed directly on vessels. Results are species- and region-specific, and particle simulations simplify larval behavior.
SOURCE
ICES Journal of Marine Science — primary study
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