Quantifying the influence of sociality on population structure in bottlenose dolphins

Authors

  • DAVID LUSSEAU,

    Corresponding author
    1. Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, George St, Cromarty, Ross-shire, IV11 8YJ, UK; and
      David Lusseau, Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, George St, Cromarty, Ross-shire, IV11 8YJ, UK. E-mail: d.lusseau@abdn.ac.uk
    Search for more papers by this author
  • BEN WILSON,

    1. Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, George St, Cromarty, Ross-shire, IV11 8YJ, UK; and
    Search for more papers by this author
    • Present address: Scottish Association of Marine Science, Dunstaffnage Marine Laboratory, Oban, Argyll, PA37 1QA, Scotland.

  • PHILIP S. HAMMOND,

    1. Sea Mammal Research Unit, Gatty Marine Laboratory, University of St Andrews, St Andrews, Fife KY16 8LB, UK
    Search for more papers by this author
  • KATE GRELLIER,

    1. Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, George St, Cromarty, Ross-shire, IV11 8YJ, UK; and
    2. Sea Mammal Research Unit, Gatty Marine Laboratory, University of St Andrews, St Andrews, Fife KY16 8LB, UK
    Search for more papers by this author
  • JOHN W. DURBAN,

    1. Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, George St, Cromarty, Ross-shire, IV11 8YJ, UK; and
    Search for more papers by this author
    • §

      Present address: National Marine Mammal Laboratory, Alaska Fisheries Science Center, NOAA Fisheries, 7600 Sand Point Way NE, Seattle WA 98115, USA.

  • KIM M. PARSONS,

    1. Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, George St, Cromarty, Ross-shire, IV11 8YJ, UK; and
    Search for more papers by this author
    • Present address: North-west Fisheries Science Center, Conservation Biology Division, NOAA Fisheries, Seattle WA 98112, USA.

  • TIM R. BARTON,

    1. Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, George St, Cromarty, Ross-shire, IV11 8YJ, UK; and
    Search for more papers by this author
  • PAUL M. THOMPSON

    1. Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, George St, Cromarty, Ross-shire, IV11 8YJ, UK; and
    Search for more papers by this author

David Lusseau, Lighthouse Field Station, School of Biological Sciences, University of Aberdeen, George St, Cromarty, Ross-shire, IV11 8YJ, UK. E-mail: d.lusseau@abdn.ac.uk

Summary

  • 1The social structure of a population plays a key role in many aspects of its ecology and biology. It influences its genetic make-up, the way diseases spread through it and the way animals exploit their environment. However, the description of social structure in nonprimate animals is receiving little attention because of the difficulty in abstracting social structure from the description of association patterns between individuals.
  • 2Here we focus on recently developed analytical techniques that facilitate inference about social structure from association patterns. We apply them to the population of bottlenose dolphins residing along the Scottish east coast, to detect the presence of communities within this population and infer its social structure from the temporal variation in association patterns between individuals.
  • 3Using network analytical techniques, we show that the population is composed of two social units with restricted interactions. These two units seem to be related to known differences in the ranging pattern of individuals. By examining social structuring at different spatial scales, we confirm that the identification of these two units is the result of genuine social affiliation and is not an artefact of their spatial distribution.
  • 4We also show that the structure of this fission-fusion society relies principally on short-term casual acquaintances lasting a few days with a smaller proportion of associations lasting several years. These findings highlight how network analyses can be used to detect and understand the forces driving social organization of bottlenose dolphins and other social species.

Ancillary