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Rolling stones and stable homes: social structure, habitat diversity and population genetics of the Hawaiian spinner dolphin (Stenella longirostris)

Authors

  • KIMBERLY R. ANDREWS,

    1. Hawai’i Institute of Marine Biology, University of Hawai’i, PO Box 1346, Kaneohe, Hawai’i 96744, USA
    2. Marine Mammal Research Program, PO Box 1106, Kailua, Hawai’i 96734, USA
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  • LESZEK KARCZMARSKI,

    1. The Swire Institute of Marine Science, The University of Hong Kong, Cape d’Aguilar, Shek O, Hong Kong
    2. Mammal Research Institute, University of Pretoria, C/o Whale Unit, PO Box 61, Cape Town 8000, South Africa
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  • WHITLOW W. L. AU,

    1. Hawai’i Institute of Marine Biology, University of Hawai’i, PO Box 1346, Kaneohe, Hawai’i 96744, USA
    2. Marine Mammal Research Program, PO Box 1106, Kailua, Hawai’i 96734, USA
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  • SUSAN H. RICKARDS,

    1. Hawai’i Marine Mammal Consortium, PO Box 1493, Kamuela, Hawai’i 96743, USA
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  • CYNTHIA A. VANDERLIP,

    1. State of Hawai’i Department of Land and Natural Resources, Division of Forestry and Wildlife, 2135 Makiki Heights Dr., Honolulu, Hawai’i 96822, USA
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  • BRIAN W. BOWEN,

    1. Hawai’i Institute of Marine Biology, University of Hawai’i, PO Box 1346, Kaneohe, Hawai’i 96744, USA
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  • E. GORDON GRAU,

    1. Hawai’i Institute of Marine Biology, University of Hawai’i, PO Box 1346, Kaneohe, Hawai’i 96744, USA
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  • ROBERT J. TOONEN

    1. Hawai’i Institute of Marine Biology, University of Hawai’i, PO Box 1346, Kaneohe, Hawai’i 96744, USA
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Kimberly R. Andrews, Fax: +1 808 236 7443; E-mail: andrewsk@hawaii.edu

Abstract

Spinner dolphins (Stenella longirostris) exhibit different social behaviours at two regions in the Hawaiian Archipelago: off the high volcanic islands in the SE archipelago they form dynamic groups with ever-changing membership, but in the low carbonate atolls in the NW archipelago they form long-term stable groups. To determine whether these environmental and social differences influence population genetic structure, we surveyed spinner dolphins throughout the Hawaiian Archipelago with mtDNA control region sequences and 10 microsatellite loci (= 505). F-statistics, Bayesian cluster analyses, and assignment tests revealed population genetic separations between most islands, with less genetic structuring among the NW atolls than among the SE high islands. The populations with the most stable social structure (Midway and Kure Atolls) have the highest gene flow between populations (mtDNA ΦST < 0.001, = 0.357; microsatellite FST = −0.001; P = 0.597), and a population with dynamic groups and fluid social structure (the Kona Coast of the island of Hawai’i) has the lowest gene flow (mtDNA 0.042 < ΦST < 0.236, P < 0.05; microsatellite 0.016 < FST < 0.040, P < 0.001). We suggest that gene flow, dispersal, and social structure are influenced by the availability of habitat and resources at each island. Genetic comparisons to a South Pacific location (= 16) indicate that Hawaiian populations are genetically depauperate and isolated from other Pacific locations (mtDNA 0.216 < FST < 0.643, P < 0.001; microsatellite 0.058 < FST < 0.090, P < 0.001); this isolation may also influence social and genetic structure within Hawai’i. Our results illustrate that genetic and social structure are flexible traits that can vary between even closely-related populations.

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