Determinants of male fitness: disentangling intra- and inter-sexual selection

Authors

  • P. S. FITZE,

    1. Department of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain
    2. Instituto Pirenaico de Ecología (IPE-CSIC), Avenida Regimiento de Galicia s/n, Jaca (Huesca), Spain
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  • J. COTE,

    1. Laboratoire Fonctionnement et Evolution des Systèmes Ecologiques, Université Pierre et Marie Curie, Paris, France
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  • J. P. MARTÍNEZ-RICA,

    1. Instituto Pirenaico de Ecología (IPE-CSIC), Avenida Regimiento de Galicia s/n, Jaca (Huesca), Spain
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  • J. CLOBERT

    1. Laboratoire Fonctionnement et Evolution des Systèmes Ecologiques, Université Pierre et Marie Curie, Paris, France
    2. Station d’Ecologie Expérimentale du CNRS à Moulis, USR2936, Moulis, Saint-Girons, France
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Patrick S. Fitze, Museo Nacional de Ciencias Naturales, Calle José Gutierrez Abascal 2, 28006 Madrid, Spain.
e-mail: patrick.fitze@mncn.csic.es

Abstract

Both intra- and inter-sexual selection may crucially determine a male’s fitness. Their interplay, which has rarely been experimentally investigated, determines a male’s optimal reproductive strategy and thus is of fundamental importance to the understanding of a male’s behaviour. Here we investigated the relative importance of intra- and inter-sexual selection for male fitness in the common lizard. We investigated which male traits predict a male’s access to reproduction allowing for both selective pressures and comparing it with a staged mating experiment excluding all types of intra-sexual selection. We found that qualitatively better males were more likely to reproduce and that sexual selection was two times stronger when allowing for both selective pressures, suggesting that inter- and intra-sexual selection determines male fitness and confirming the existence of multi-factorial sexual selection. Consequently, to optimize fitness, males should trade their investment between the traits, which are important for inter- and intra-sexual selection.

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