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Microsatellite and mitochondrial DNA analyses of the genetic structure of blacktip shark (Carcharhinus limbatus) nurseries in the northwestern Atlantic, Gulf of Mexico, and Caribbean Sea

Authors

  • D. B. KEENEY,

    Corresponding author
    1. Fisheries and Illinois Aquaculture Center, Department of Zoology, Life Sciences II, Southern Illinois University Carbondale, 1125 Lincoln Drive, Carbondale, IL 62901–6511, USA,
    2. Present address: Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand
      Devon B. Keeney, Fax: 64 3 479 7584; E-mail: deron.keeney@stonebow.otago.ac.nz
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  • M. R. HEUPEL,

    1. Center for Shark Research, Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA
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  • R. E. HUETER,

    1. Center for Shark Research, Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA
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  • E. J. HEIST

    1. Fisheries and Illinois Aquaculture Center, Department of Zoology, Life Sciences II, Southern Illinois University Carbondale, 1125 Lincoln Drive, Carbondale, IL 62901–6511, USA,
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Devon B. Keeney, Fax: 64 3 479 7584; E-mail: deron.keeney@stonebow.otago.ac.nz

Abstract

We investigated the genetic structure of blacktip shark (Carcharhinus limbatus) continental nurseries in the northwestern Atlantic Ocean, Gulf of Mexico, and Caribbean Sea using mitochondrial DNA control region sequences and eight nuclear microsatellite loci scored in neonate and young-of-the-year sharks. Significant structure was detected with both markers among nine nurseries (mitochondrial ΦST = 0.350, P < 0.001; nuclear ΦST = 0.007, P < 0.001) and sharks from the northwestern Atlantic, eastern Gulf of Mexico, western Gulf of Mexico, northern Yucatan, and Belize possessed significantly different mitochondrial DNA haplotype frequencies. Microsatellite differentiation was limited to comparisons involving northern Yucatan and Belize sharks with nuclear genetic homogeneity throughout the eastern Gulf of Mexico, western Gulf of Mexico, and northwestern Atlantic. Differences in the magnitude of maternal vs. biparental genetic differentiation support female philopatry to northwestern Atlantic, Gulf of Mexico, and Caribbean Sea natal nursery regions with higher levels of male-mediated gene flow. Philopatry has produced multiple reproductive stocks of this commercially important shark species throughout the range of this study.

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