Density-dependent selection on horn phenotype in Soay sheep

Clutton-Brock, T. H. and Wilson, K. and Stevenson, I. R. (1997) Density-dependent selection on horn phenotype in Soay sheep. Philosophical Transactions of the Royal Society B: Biological Sciences, 352 (1355). pp. 839-850. ISSN 0962-8436

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Abstract

In the naturally regulated population of Soay sheep (Ovis aries L.) on Hirta (St Kilda), 12% of males and 24% of females have scurred horns. This trait reduces the competitive ability of males in the mating season but is associated with higher overwinter survival rates in both sexes (Moorcroft et al. 1996). In this paper, we show that scurred females also show higher conception rates and weaning rates than non-scurred ones, and that these differences are associated with heavier maternal body weight as well as higher birth weights of offspring. Selection pressures favouring scurredness in females vary with population density and are generally more pronounced among younger animals than adults. We discuss these results with reference to recent suggestions that temporal fluctuation in selection pressures may help to maintain genetic diversity within populations. We suggest that selection against scurredness operating through male mating success is opposed by selection favouring this trait, operating through the breeding success of females and the survival of both sexes.

Item Type: Journal Article
Journal or Publication Title: Philosophical Transactions of the Royal Society B: Biological Sciences
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/1100
Subjects:
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 128493
Deposited By: ep_importer_pure
Deposited On: 26 Oct 2018 15:34
Refereed?: Yes
Published?: Published
Last Modified: 30 Sep 2019 21:20
URI: https://eprints.lancs.ac.uk/id/eprint/128493

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