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Significant population structure and asymmetric gene flow patterns amidst expanding populations of Clinus cottoides (Perciformes, Clinidae): application of molecular data to marine conservation planning in South Africa

Authors

  • SOPHIE VON DER HEYDEN,

    1. Evolutionary Genomics Group, Department of Botany and Zoology, Stellenbosch University, Private Bag XI, Matieland 7602, South Africa,
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  • KIM PROCHAZKA,

    1. International Ocean Institute Southern Africa, Department of Biodiversity and Conservation Biology, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa,
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    • §

      Present address: Department of Environmental Affairs and Tourism, Branch: Marine and Coastal Management, Private Bag X2, Roggebaai, Cape Town 8012, South Africa

  • RAURI C. K. BOWIE

    1. Evolutionary Genomics Group, Department of Botany and Zoology, Stellenbosch University, Private Bag XI, Matieland 7602, South Africa,
    2. Museum of Vertebrate Zoology and Department of Integrative Biology, 3101 Valley Life Science Building, University of California, Berkeley, CA 94720, USA
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S. von der Heyden, Fax: +27 (0)21 8082405; E-mail: svdh@sun.ac.za

Abstract

Clinus cottoides is a fish endemic to the coast of South Africa, predominantly inhabiting rock pools. All South African clinids are viviparous, but probably breed throughout the year; as such, their dispersal may be limited, unlike species with pelagic larval stages. We analysed 343 fish from 14 localities on the west, south and east coasts using two mitochondrial genes and the second intron of the S7 ribosomal gene. Mitochondrial DNA analyses recovered significant genetic differentiation between fish populations from the east coast and other sampling locations, with a second break found between Gansbaai and Cape Agulhas on the south coast. Nuclear DNA recovered shallower, but significant, levels of population structure. Coalescent analyses suggested remarkably asymmetrical gene flow between sampling locations, suggesting that the cold Atlantic Benguela Current and Indian Ocean Agulhas counter-current play important roles in facilitating dispersal. There was no gene flow between the east coast and the other sites, suggesting that these populations are effectively isolated. Divergence times between them were estimated to at least 68 000 years. Neutrality tests and mismatch distributions suggest recent population expansions, with the exception of peripheral western and eastern populations (possibly a consequence of environmental extremes at the edge of the species distribution). Analyses of the current South African marine protected areas network show that it is not connected and that De Hoop, one of South Africa's largest marine reserves, appears to be an important source population of recruits to both the south and southwest coasts.

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