Data from: The Pillars of Hercules as a bathymetric barrier to gene-flow promoting isolation in a global deep-sea shark (Centroscymnus coelolepis)

Knowledge of the mechanisms limiting connectivity and gene-flow in
deep-sea ecosystems is limited, especially for deep-sea sharks. The
Portuguese dogfish (Centroscymnus coelolepis) is a globally distributed
and Near Threatened deep-sea shark. C. coelolepis population structure was
studied using 11 nuclear microsatellite markers and a 497 bp fragment from
the mtDNA Control Region. High levels of genetic homogeneity across the
Atlantic (ΦST=-0.0091, FST= 0.0024, P > 0.05) were found suggesting
one large population unit at this basin. The low levels of genetic
divergence between Atlantic and Australia (ΦST= 0.0744, P<0.01;
FST=0.0015, P > 0.05) further suggested that this species may be
able to maintain some degree of genetic connectivity even across ocean
basins. In contrast, sharks from the Mediterranean Sea exhibited marked
genetic differentiation from all other localities studied (ΦST=0.3808,
FST=0.1149, P < 0.001). This finding suggests that the shallow
depth of the Strait of Gibraltar acts as a barrier to dispersal and that
isolation and genetic drift may have had an important role shaping the
Mediterranean shark population over time. Analyses of life-history traits
allowed the direct comparison among regions providing a complete
characterization of this shark population. Sharks from the Mediterranean
had markedly smaller adult body size and size at maturity compared to
Atlantic and Pacific individuals. Together these results suggest the
existence of an isolated and unique population of C. coelolepis inhabiting
the Mediterranean that most likely became separated from the Atlantic in
the late Pleistocene.