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Sperm whale population structure in the eastern and central North Pacific inferred by the use of single-nucleotide polymorphisms, microsatellites and mitochondrial DNA

Authors

  • SARAH L. MESNICK,

    1. Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 3333 North Torrey Pines Court, La Jolla, CA 92037, USA
    2. Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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  • BARBARA L. TAYLOR,

    1. Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 3333 North Torrey Pines Court, La Jolla, CA 92037, USA
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  • FREDERICK I. ARCHER,

    1. Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 3333 North Torrey Pines Court, La Jolla, CA 92037, USA
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  • KAREN K. MARTIEN,

    1. Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 3333 North Torrey Pines Court, La Jolla, CA 92037, USA
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  • SERGIO ESCORZA TREVIÑO,

    1. Department of Biological Sciences, California State University Los Angeles, 5151 State University Drive, Los Angeles, CA 90032, USA
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  • BRITTANY L. HANCOCK-HANSER,

    1. Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 3333 North Torrey Pines Court, La Jolla, CA 92037, USA
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  • SANDRA CAROLINA MORENO MEDINA,

    1. Laboratorio de Ecología Molecular, Universidad Autónoma de Baja California, Km 103 Carretera Tijuana-Ensenada, Ensenada, Baja California 22800, México
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  • VICTORIA L. PEASE,

    1. Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 3333 North Torrey Pines Court, La Jolla, CA 92037, USA
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  • KELLY M. ROBERTSON,

    1. Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 3333 North Torrey Pines Court, La Jolla, CA 92037, USA
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  • JANICE M. STRALEY,

    1. University of Alaska Southeast, Sitka Campus, 1332 Seaward Avenue, Sitka, AK 99835, USA
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  • ROBIN W. BAIRD,

    1. Cascadia Research Collective, 218 1/2 W 4th Ave., Olympia, WA 98501, USA
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  • JOHN CALAMBOKIDIS,

    1. Cascadia Research Collective, 218 1/2 W 4th Ave., Olympia, WA 98501, USA
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  • GREGORY S. SCHORR,

    1. Cascadia Research Collective, 218 1/2 W 4th Ave., Olympia, WA 98501, USA
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  • PAUL WADE,

    1. National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way NE, Building 4, Seattle, WA 98115, USA
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  • VLADIMIR BURKANOV,

    1. National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way NE, Building 4, Seattle, WA 98115, USA
    2. Kamchatka Branch of the Pacific Geophysical Institute, FEB, RAS, 6 Partizankaya Street, Petropavlovsk-Kamchatsky, Russia
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  • CHRIS R. LUNSFORD,

    1. Auke Bay Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 11305 Glacier Highway, Juneau, AK 99801, USA
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  • LUKE RENDELL,

    1. School of Biology, Bute Medical Building, Queen‘s Terrace, St. Andrews, Fife, KY16 9TS, UK
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  • PHILLIP A. MORIN

    1. Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 3333 North Torrey Pines Court, La Jolla, CA 92037, USA
    2. Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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Sarah L. Mesnick, Fax: +1 (858) 546 7003; E-mail: sarah.mesnick@noaa.gov

Abstract

We use mitochondrial DNA (mtDNA) (400 bp), six microsatellites and 36 single-nucleotide polymorphisms (SNPs), 20 of which were linked, to investigate population structure of sperm whales (Physeter macrocephalus) in the eastern and central North Pacific. SNP markers, reproducible across technologies and laboratories, are ideal for long-term studies of globally distributed species such as sperm whales, a species of conservation concern because of both historical and contemporary impacts. We estimate genetic differentiation among three strata in the temperate to tropical waters where females are found: California Current, Hawai`i and the eastern tropical Pacific. We then consider how males on sub-Arctic foraging grounds assign to these strata. The California Current stratum was differentiated from both the other strata (< 0.05) for mtDNA, microsatellites and SNPs, suggesting that the region supports a demographically independent population and providing the first indication that males may exhibit reproductive philopatry. Comparisons between the Hawai`i stratum and the eastern tropical Pacific stratum are not conclusive at this time. Comparisons with Alaska males were statistically significant, or nearly so, from all three strata and individuals showed mixed assignment to, and few exclusions from, the three potential source strata, suggesting widespread origin of males on sub-Arctic feeding grounds. We show that SNPs have sufficient power to detect population structure even when genetic differentiation is low. There is a need for better analytical methods for SNPs, especially when linked SNPs are used, but SNPs appear to be a valuable marker for long-term studies of globally dispersed and highly mobile species.

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