title: The Pillars of Hercules as a bathymetric barrier to gene flow promoting isolation in a global deep-sea shark (Centroscymnus coelolepis).
abstract: Knowledge of the mechanisms limiting connectivity and gene flow in deep-sea ecosystems is scarce, 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 (Φ(ST) = -0.0091, F(ST) = 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 (Φ(ST) = 0.0744, P < 0.01; F(ST) = 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 (Φ(ST) = 0.3808, F(ST) = 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's populations. 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.
authors.affiliation: MARE-Marine and Environmental Sciences Centre, Department of Oceanography and Fisheries, University of the Azores, Rua Prof. Dr. Frederico Machado, Horta, Azores, Portugal.|IMAR-Institute of Marine Research, Department of Oceanography and Fisheries, University of the Azores, Rua Prof. Dr. Frederico Machado, Horta, Azores, Portugal.
authors.forename: Diana
authors.initials: D
authors.lastname: Catarino
authors.affiliation: Institute of Marine Research (IMR), Flødevigen, N-4817 His, Norway.|University of Agder, Kristiansand, N-4604, Norway.|Department of Biosciences, University of Oslo, Centre for Ecological and Evolutionary Synthesis (CEES), PO Box 1066 Blindern, Oslo, N-0316, Norway.
authors.forename: Halvor
authors.initials: H
authors.lastname: Knutsen
authors.affiliation: CIBIO-U.P., Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Rua Padre Armando Quintas, Vairão, 4485-661, Portugal.|College of William and Mary, Virginia Institute of Marine Science, Route 1208, Greate Road, Gloucester Point, 23062, VA, USA.
authors.forename: Ana
authors.initials: A
authors.lastname: Veríssimo
authors.affiliation: Institute of Marine Research (IMR), Flødevigen, N-4817 His, Norway.|University of Agder, Kristiansand, N-4604, Norway.|Department of Biosciences, University of Oslo, Centre for Ecological and Evolutionary Synthesis (CEES), PO Box 1066 Blindern, Oslo, N-0316, Norway.
authors.forename: Esben Moland
authors.initials: EM
authors.lastname: Olsen
authors.affiliation: Department of Biosciences, University of Oslo, Centre for Ecological and Evolutionary Synthesis (CEES), PO Box 1066 Blindern, Oslo, N-0316, Norway.
authors.forename: Per Erik
authors.initials: PE
authors.lastname: Jorde
authors.affiliation: MARE-Marine and Environmental Sciences Centre, Department of Oceanography and Fisheries, University of the Azores, Rua Prof. Dr. Frederico Machado, Horta, Azores, Portugal.|IMAR-Institute of Marine Research, Department of Oceanography and Fisheries, University of the Azores, Rua Prof. Dr. Frederico Machado, Horta, Azores, Portugal.
authors.forename: Gui
authors.initials: G
authors.lastname: Menezes
authors.affiliation: Institute of Marine Research (IMR), Flødevigen, N-4817 His, Norway.
authors.forename: Hanne
authors.initials: H
authors.lastname: Sannæs
authors.affiliation: Department of Life Sciences, University of Trieste, Via Licio Giorgieri 5, Trieste, 34127, Italy.
authors.forename: David
authors.initials: D
authors.lastname: Stanković
authors.affiliation: Institut de Ciències del Mar, CSIC, Passeig Marítim de la Barceloneta 37-49, Barcelona, 08003, Spain.
authors.forename: Joan Baptista
authors.initials: JB
authors.lastname: Company
authors.affiliation: Marine Laboratory, Marine Scotland-Science, PO Box 101, 375 Victoria Road, Aberdeen, AB11 9DB, UK.
authors.forename: Francis
authors.initials: F
authors.lastname: Neat
authors.affiliation: Department of Life and Environmental Sciences, Università Politecnica delle Marche, Ancona, 60131, Italy.|Stazione Zoologica Anton Dohrn, Villa Comunale, Naples, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Danovaro
authors.affiliation: Department of Life and Environmental Sciences, Università Politecnica delle Marche, Ancona, 60131, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Dell'Anno
authors.affiliation: School of BioSciences, The University of Melbourne, Parkville, Vic., 3010, Australia.
authors.forename: Bastien
authors.initials: B
authors.lastname: Rochowski
authors.affiliation: IMAR-Institute of Marine Research, Department of Oceanography and Fisheries, University of the Azores, Rua Prof. Dr. Frederico Machado, Horta, Azores, Portugal.|CNR-ISSIA, Via de Marini 6, Genova, 16149, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Stefanni
mesh_terms: D000818:Animals; D001267:Atlantic Ocean; D005075:Biological Evolution; D004272:DNA, Mitochondrial / Q000235:genetics; D005260:Female; D051456:Gene Flow; D005828:Genetics, Population; D005838:Genotype; D008297:Male; D008522:Mediterranean Sea; D018895:Microsatellite Repeats; D010140:Pacific Ocean; D017422:Sequence Analysis, DNA; D012754:Sharks / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial
keywords: Mediterranean; barriers to dispersal; deep-sea shark; isolation; population structure