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Predictors of reproductive cost in female Soay sheep

  1. G. TAVECCHIA1,2,*,
  2. T. COULSON1,†,
  3. B. J. T. MORGAN2,
  4. J. M. PEMBERTON3,
  5. J. C. PILKINGTON3,
  6. F. M. D. GULLAND4,
  7. T. H. CLUTTON-BROCK1

Article first published online: 19 JAN 2005

DOI: 10.1111/j.1365-2656.2005.00916.x

Issue

Journal of Animal Ecology

Journal of Animal Ecology

Volume 74, Issue 2, pages 201–213, March 2005

Additional Information

How to Cite

TAVECCHIA, G., COULSON, T., MORGAN, B. J. T., PEMBERTON, J. M., PILKINGTON, J. C., GULLAND, F. M. D. and CLUTTON-BROCK, T. H. (2005), Predictors of reproductive cost in female Soay sheep. Journal of Animal Ecology, 74: 201–213. doi: 10.1111/j.1365-2656.2005.00916.x

Author Information

  1. 1

    Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK,

  2. 2

    Institute of Mathematics and Statistics, University of Kent, Canterbury, CT2 7NF, UK,

  3. 3

    Institute of Cell, Animal and Population Biology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK, and

  4. 4

    The Marine Mammal Center, 1065 Fort Cronkhite, Sausalito, CA 9496, USA

  1. †

    Present address: Department of Biological Sciences, Imperial College at Silwood Park, Ascot, Berks, SL5 7PY, UK

* *Present address and correspondence: IMEDEA – UIB/CSIC, C. M. Marques 21, 07190, Esporles, Spain. E-mail: g.tavecchia.uib.es

Publication History

  1. Issue published online: 19 JAN 2005
  2. Article first published online: 19 JAN 2005
  3. Received 17 March 2004; revision received 12 May 2004

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Keywords:

  •  multistate model;
  • recruitment;
  • survival;
  • trade-off function

Summary

  • 1
    We investigate factors influencing the trade-off between survival and reproduction in female Soay sheep (Ovis aries). Multistate capture–recapture models are used to incorporate the state-specific recapture probability and to investigate the influence of age and ecological conditions on the cost of reproduction, defined as the difference between survival of breeder and non-breeder ewes on a logistic scale.
  • 2
    The cost is identified as a quadratic function of age, being greatest for females breeding at 1 year of age and when more than 7 years old. Costs, however, were only present during severe environmental conditions (wet and stormy winters occurring when population density was high).
  • 3
    Winter severity and population size explain most of the variation in the probability of breeding for the first time at 1 year of life, but did not affect the subsequent breeding probability.
  • 4
    The presence of a cost of reproduction was confirmed by an experiment where a subset of females was prevented from breeding in their first year of life.
  • 5
    Our results suggest that breeding decisions are quality or condition dependent. We show that the interaction between age and time has a significant effect on variation around the phenotypic trade-off function: selection against weaker individuals born into cohorts that experience severe environmental conditions early in life can progressively eliminate low-quality phenotypes from these cohorts, generating population-level effects.
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