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Flippers versus feet: comparative trends in aquatic and non-aquatic carnivores

  1. Olaf R.P. Bininda-Emonds1,
  2. John L. Gittleman2,*,
  3. Colleen K. Kelly1

Article first published online: 26 MAR 2002

DOI: 10.1046/j.1365-2656.2001.00499.x

Issue

Journal of Animal Ecology

Journal of Animal Ecology

Volume 70, Issue 3, pages 386–400, May 2001

Additional Information

How to Cite

Bininda-Emonds, O. R.P., Gittleman, J. L. and Kelly, C. K. (2001), Flippers versus feet: comparative trends in aquatic and non-aquatic carnivores. Journal of Animal Ecology, 70: 386–400. doi: 10.1046/j.1365-2656.2001.00499.x

Author Information

  1. 1

    Department of Zoology, University of Oxford, Oxford OX1 3PS, UK; and

  2. 2

    Department of Biology, Gilmer Hall, University of Virginia, Charlottesville, VA, 22903, USA

* John L. Gittleman, Department of Biology, Gilmer Hall, University of Virginia, Charlottesville, VA, 22903, USA. E-mail:JLGittleman@virginia.edu

Publication History

  1. Issue published online: 26 MAR 2002
  2. Article first published online: 26 MAR 2002

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Keywords:

  • aquatic adaptations;
  • comparative method;
  • independent contrasts;
  • phylogeny;
  • terrestrial ecology

Summary

  • 1
    It is commonly accepted that many adaptations characterize carnivores that live in water. However, no comparative tests have ever shown systematic differences between aquatic and terrestrial carnivore species as a whole. We examine numerous hypotheses that purport to distinguish aquatic and terrestrial carnivores using 20 morphological, life history, physiological and ecological traits.
  • 2
     Using the method of independent contrasts with a complete species-level phylogeny of extant carnivores, we found few differences between aquatic and terrestrial species. Compared to terrestrial sister taxa, aquatic carnivores are streamlined (increased head and body length for a given body weight), have larger brains, smaller litter sizes, shorter interbirth intervals, and shorter lifespans.
  • 3
     Some of these differences are important functionally. Larger brain size may be related to increased cognitive and sensory needs required for an amphibious lifestyle; smaller litters are likely associated with increased neonatal survival amidst competition for suitable breeding sites and advantages accruing to increased precociality.
  • 4
     We conclude that broad differentiation of carnivores into aquatic and terrestrial ecotypes is not useful given that adaptive differences between these groups are limited and seemingly no more numerous than those that occur within each ecological group.
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