Bezuidenhout K, Nel R, Schoeman DS, Hauser L

Historic dispersal barriers determine genetic structure and connectivity in a sandy beach brooder

Sandy beach supratidal invertebrates have typically low vagility, leaving them vulnerable to habitat destruction and extirpation, although environmental barriers to connectivity are poorly known. Bezuidenhout and co-workers examined the role of contemporary and historic dispersal barriers on the genetic (COI) structure of one such species, the isopod Tylos capensis (pill bug). Genetic structure was congruent with historical dispersal barriers (rocky coasts) on Pleistocene coastlines, while populations historically connected by beach habitat lacked genetic differentiation even if they were currently isolated. Pill bugs therefore appear prone to population isolation. While a network of protected beaches is unlikely to facilitate gene flow among populations, protection of beaches with intact littoral active zone is imperative to preserve this and other high shore species.

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