Sex-limited expression of ornamental feathers in birds |
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Authors: | Cuervo Jose Javier; Moller Anders Pape |
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Institution: | a
Estación
Biológica de
Doñana, Consejo Superior de Investigaciones
Científicas,
Pabellón del
Perú, Avenida
María Luisa s/n, E-41013 Sevilla, Spain
b
Laboratoire d'Ecologie, CNRS UMR 7652,
Université Pierre et Marie Curie,
Bât. A, 7ème
étage, 7 quai St. Bernard, F-75252 Paris Cedex
05, France |
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Abstract: | Extravagant secondary sexual characters show sexual size dimorphismin some species but are completely sex limited in others. Sexualornamentation has been hypothesized to benefit mainly malesthrough sexual selection, but the costs of secondary sexualcharacters initially would be experienced by both sexes. Theevolution of sexual size dimorphism of ornaments and, eventually,
the complete sex-limited expression of these characters, willdepend on the effects of sexual and natural selection on thetwo sexes. A phylogenetic analysis controlling for similaritiesdue to common ancestry of 60 independent evolutionary originsof feather ornamentation in birds was used to investigate ecologicalfactors correlated with sexual size dimorphism and sex-limited
expression of secondary sexual characters. When the size ofan ornament is large relative to body size, the trait willbe particularly costly for females, resulting in selectionfor increased sexual size dimorphism of the ornament. Indeed,sexual size dimorphism of ornaments was positively related
to the relative size of male ornaments but was unrelated torelative size of female ornaments. Species with polygynousand lekking mating systems with little or no male parentalcare (in particular nest building and incubation) demonstratedsex-limited expression of ornaments as compared to monogamous
species. Species with no food provisioning of offspring by themale showed a trend for increased sexual size dimorphism ofornaments. Therefore, large natural selection costs duringreproduction imposed by the expression of secondary sexualcharacters are related to the evolution of sexual size dimorphismof ornaments and eventually their complete loss from females. |
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Keywords: | sex limitation sexual selection sexual size dimorphism |
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