Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures

The Genetic Connectivity of a Euryhaline Elasmobranch, the Atlantic Stingray (Dasyatis sabina)

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Joint Meeting of Ichthyologists and Herpetologists, Reno, Nevada, July 16-19, 2015

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Identifying the genetic connectivity of elasmobranchs inhabiting coastal waters remains an important global priority, as these species are particularly susceptible to human mediated impacts and declines given their close proximity to highly populated areas. The Atlantic stingray (Dasyatis sabina), a small, coastal species whose range spans the western North Atlantic (Florida to Chesapeake Bay) and Gulf of Mexico, is one of the few elasmobranchs capable of occupying both estuarine and freshwater habitats. Within Florida waters, a putative ‘resident’ population inhabits the freshwater St. Johns River System (SJRS); however, the extent of this population’s connectivity to the remainder of its distribution remains unknown. To examine the genetic connectivity of the Atlantic stingray across its southern US distribution, including the SJRS, a total of 312 individuals from 11 sampling locations were genotyped at nine species-specific microsatellite loci. Population- and individual-level analyses identified high levels of genetic population structure among collections, with coastal populations within the Gulf of Mexico showing high genetic structure (FST = 0.011 – 0.034; P <0.05) and a signal of isolation by distance (R2 = 0.957; P = 0.041). Interestingly, individual-based analyses showed that freshwater SJRS animals were differentiated from other locations, suggesting that these individuals may truly represent a ‘resident’ freshwater population. The presence of high genetic population structure, coupled with what may be locally adapted populations, suggests that care must be taken to conserve this species, as the extinction of even a single population may result in the irreversible loss of genetic diversity and adaptive potential.

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