Rise of oceanographic barriers in continuous populations of a cetacean: the genetic structure of harbour porpoises in Old World waters
1 MARE – Laboratory for Oceanology, University of Liège, Bat B6c, Liège (Sart Tilman) 4000, Belgium
2 INRA, UMR CBGP (INRA/IRD/Cirad/Montpellier SupAgro), Campus international de Baillarguet, CS 30016, F-34988 Montferrier-sur-Lez cedex, France
3 Computational and Molecular Population Genetics Laboratory, Zoological Institute, University of Bern, Switzerland
4 Marine Mammal Division, Institute of Marine Research, Bergen, Norway
5 Molecular Systematics Laboratory, South African National Biodiversity Institute, Private Bag X7, Claremont 7735, Cape Town, South Africa
6 Department of Zoology, University College, Dublin, Ireland
7 Laboratory of Biotechnological Research in Ecology, Medicine and Aquaculture (BREMA), Simferopol, Ukraine
8 Portuguese Wildlife Society Estação de Campo de Quiaios. Apt 16 EC Quiaios. 3081-101 Figueira da Foz, Portugal
9 Department of Pathology, Veterinary College, Sart Tilman B43, University of Liège, 4000 Liège, Belgium
10 Coordinadora para o Estudio dos Mamiferos MAriños, CEMMA, Gondomar, Spain
11 Faculty of Fisheries, Istanbul University, Ordu Cad. 200, Laleli-Istanbul, Turkey
12 Centre de Recherche sur les Mammifères Marins, Institut de la Mer et du Littoral, Avenue du Lazaret, Port des Minimes, 17000 La Rochelle, France
13 Department of Zoology, Ecology and Plant Science, University College, Cork, Ireland
14 Instituto da Conservação da Natureza, Rua de Santa Marta, 55, 1150-999 Lisboa, Portugal
15 Forschungs- und Technologie Zentrum, Westküste, Universität Kiel, Hafentörn 1, 25761 Büsum, Germany
16 Marine Research Institute, Skúlagata 4, P.O. Box 1390, 121 Reykjavík, Iceland
17 Génétique des Microorganismes, Département des Sciences de la Vie, Institut de Botanique B22, Université de Liège, 4000 Liège, Belgium
BMC Biology 2007, 5:30 doi:10.1186/1741-7007-5-30Published: 25 July 2007
Understanding the role of seascape in shaping genetic and demographic population structure is highly challenging for marine pelagic species such as cetaceans for which there is generally little evidence of what could effectively restrict their dispersal. In the present work, we applied a combination of recent individual-based landscape genetic approaches to investigate the population genetic structure of a highly mobile extensive range cetacean, the harbour porpoise in the eastern North Atlantic, with regards to oceanographic characteristics that could constrain its dispersal.
Analyses of 10 microsatellite loci for 752 individuals revealed that most of the sampled range in the eastern North Atlantic behaves as a 'continuous' population that widely extends over thousands of kilometres with significant isolation by distance (IBD). However, strong barriers to gene flow were detected in the south-eastern part of the range. These barriers coincided with profound changes in environmental characteristics and isolated, on a relatively small scale, porpoises from Iberian waters and on a larger scale porpoises from the Black Sea.
The presence of these barriers to gene flow that coincide with profound changes in oceanographic features, together with the spatial variation in IBD strength, provide for the first time strong evidence that physical processes have a major impact on the demographic and genetic structure of a cetacean. This genetic pattern further suggests habitat-related fragmentation of the porpoise range that is likely to intensify with predicted surface ocean warming.