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Stable isotopic niche predicts fitness of prey in a wolf–deer system

Authors

  • C. T. DARIMONT,

    Corresponding author
    1. Department of Biology, PO Box 3020, Stn. CSC, University of Victoria, Victoria, British Columbia, Canada, V8W 3N5
    2. Raincoast Conservation Society, PO Box 26, Bella Bella, British Columbia, Canada, V0T 1B0
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  • P. C. PAQUET,

    1. Raincoast Conservation Society, PO Box 26, Bella Bella, British Columbia, Canada, V0T 1B0
    2. Faculty of Environmental Design, University of Calgary, Calgary, Alberta, Canada, T2N 1N4
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  • T. E. REIMCHEN

    1. Department of Biology, PO Box 3020, Stn. CSC, University of Victoria, Victoria, British Columbia, Canada, V8W 3N5
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E-mail: cdarimon@uvic.ca

Abstract

Interindividual variation in niche presents a potentially central object on which natural selection can act. This may have important evolutionary implications because habitat use governs a suite of selective forces encountered by foragers. In a free-living native black-tailed deer, Odocoileus hemionus, population from coastal British Columbia, we used stable isotope analysis to identify individual variation in foraging niche and investigated its relationship to fitness. Using an intragenerational comparison of surviving and nonsurviving O. hemionus over 2 years of predation by wolves, Canis lupus, we detected resource-specific fitness. Individuals with isotopic signatures that suggested they foraged primarily in cedar (Thuja plicata)-dominated and low-elevation hemlock (Tsuga heterophylla)-dominated forest stands were more likely to be killed by C. lupus. High-quality forage in T. plicata stands, as indexed by protein content, may be involved in maintaining this foraging phenotype. Moreover, nonsurvivors diverged more than survivors from median isotopic signatures, suggesting selection against foraging specialization. Stable isotope analysis provides a novel opportunity to integrate ecological and selective landscapes in order to identify underlying ecological mechanisms of selection and provide insight into the maintenance of variability. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90, 125–137.

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