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Assessing the intensity of sexual selection on male body mass and antler length in roe deer Capreolus capreolus: is bigger better in a weakly dimorphic species?

Authors

  • Cécile Vanpé,

    1. Laboratoire Comportement et Ecologie de la Faune Sauvage, Inst. National de la Recherche Agronomique, BP 52627, FR–31326 Castanet-Tolosan Cedex, France
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  • Jean-Michel Gaillard,

    1. Laboratoire Comportement et Ecologie de la Faune Sauvage, Inst. National de la Recherche Agronomique, BP 52627, FR–31326 Castanet-Tolosan Cedex, France
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  • Petter Kjellander,

    1. Laboratoire Comportement et Ecologie de la Faune Sauvage, Inst. National de la Recherche Agronomique, BP 52627, FR–31326 Castanet-Tolosan Cedex, France
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  • Olof Liberg,

    1. Laboratoire Comportement et Ecologie de la Faune Sauvage, Inst. National de la Recherche Agronomique, BP 52627, FR–31326 Castanet-Tolosan Cedex, France
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  • Daniel Delorme,

    1. Laboratoire Comportement et Ecologie de la Faune Sauvage, Inst. National de la Recherche Agronomique, BP 52627, FR–31326 Castanet-Tolosan Cedex, France
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  • A. J. Mark Hewison

    1. Laboratoire Comportement et Ecologie de la Faune Sauvage, Inst. National de la Recherche Agronomique, BP 52627, FR–31326 Castanet-Tolosan Cedex, France
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A. J. M. Hewison, Laboratoire Comportement et Ecologie de la Faune Sauvage, Inst. National de la Recherche Agronomique, BP 52627, FR–31326 Castanet-Tolosan Cedex, France. E-mail: mark.hewison@toulouse.inra.fr

Abstract

Little is known about traits under sexual selection in territorial mammals with low sexual size dimorphism. We examined the potential for sexual selection on male body mass and antler length in the European roe deer Capreolus capreolus, a territorial ungulate in which males are less than 10% heavier than females. Independently, both body mass and antler length (irrespective of age) had a positive effect on male yearly breeding success. However, when corrected for body mass, antler length at a given mass only had a slight effect on male breeding success. This suggests that: (1) ‘bigger is better’ and (2) sexual selection is responsible for at least part of the observed variation in body mass and antler length in roe deer. High body mass and large antlers may be advantageous to males for two reasons: (1) they enhance fighting ability and dominance, so allowing males to defend better their territory and hence access mates, and (2) they attract females because they are honest signals of male phenotypic quality. This suggests that, even in weakly dimorphic ungulate species, sexual selection may lead to a marked influence of body mass on male breeding success, as long as body mass is also strongly selected in females.

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