MEPS 341:265-276 (2007)  -  doi:10.3354/meps341265

Genetic differentiation in bottlenose dolphins from South Australia: association with local oceanography and coastal geography

Kerstin Bilgmann1,2,*, Luciana M. Möller1,2, Robert G. Harcourt1, Susan E. Gibbs1, Luciano B. Beheregaray2

1Marine Mammal Research Group, Graduate School of the Environment, and 2Molecular Ecology Laboratory, Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia

ABSTRACT: For many marine organisms, including large, long-lived predators, the factors affecting connectivity between populations are still largely unknown. We assessed levels of genetic differentiation and dispersal patterns of bottlenose dolphins Tursiops sp. across Spencer Gulf and coastal areas west of the gulf in the Great Australian Bight, South Australia (SA), using data from mitochondrial DNA control region sequences and 6 microsatellite loci. Marked genetic differentiation and low migration were detected between dolphins of Spencer Gulf and those inhabiting coastal areas west of the gulf. We hypothesise that the restriction to dolphin gene flow is influenced by an oceanographic front at the mouth of Spencer Gulf that builds up over the austral summer and exhibits strong differences in water temperatures and salinity levels. It appears that the genetic subdivision reported here is a recent phenomenon, a finding consistent with the known geomorphologic history of the region. Coastal bottlenose dolphins from SA are evolutionarily divergent from other bottlenose dolphin species and are potentially under threat due to ongoing human-related mortality. The information from this study can, therefore, be used for the development of much-needed conservation management strategies.

KEY WORDS: Population genetic structure · Cetacean · Phylogeography · Marine connectivity · Microsatellites · Mitochondrial DNA · Temperature · Salinity

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