Behavioral Ecology Advance Access originally published online on September 20, 2007
Behavioral Ecology 2007 18(6):1123-1131; doi:10.1093/beheco/arm088
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Iridescent structurally based coloration of eyespots correlates with mating success in the peacock
a Conservation des Espèces, Restauration et Suivi des Populations, CNRS UMR 5173, MNHN, Paris, France b School of Biological Sciences, University of Bristol, Bristol, UK c Département Ecologie et Gestion de la Biodiversité, CNRS UMR 7179, MNHN, Brunoy, France d School of Biomedical Sciences, University of Queensland, Brisbane, Queensland 4072, Australia e Biogéosciences, Université de Bourgogne, CNRS UMR 5561, Dijon, France
Address correspondence to A. Loyau, who is now at Station d'Ecologie Expérimentale du CNRS à Moulis, CNRS USR 2936, Moulis, France. E-mail: al{at}adeline-loyau.net.
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Abstract |
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Gaudy plumage coloration is a widespread ornamental trait in birds and thought to be sexually selected. Although much attention has been devoted to structural coloration reflecting in UV, the signaling function of structural colors lacking UV reflectance and those that exhibit iridescence coloration are poorly documented. The train of the peacock (Pavo cristatus), a classical example of a sexually selected trait, is composed of iridescent structurally colored eyespots not reflecting in UV. Until today, the role played by the structural color of the eyespots in female mate choice has never been investigated using spectrometry. We measured eyespot coloration from a stationary angle (static coloration) and the change in coloration resulting from different angles (iridescent coloration). We assessed coloration with reflectance spectrometry, and we analyzed reflectance spectra using 2 methods. First, we extracted the reflectance spectra shape descriptors hue, brightness, and chroma. Second, we computed color and brightness contrasts signaled by eyespot feathers, taking peafowl color visual sensitivity into account. Iridescence was estimated by the maximal change for all parameters. Brightness was correlated with male mating success. The maximal change in color contrast was correlated with both the frequency of male visitation by females and male mating success. These results suggest that peahens can use both static and dynamic (i.e., iridescent) aspects of plumage structural coloration as signals to detect and choose their mates.
Key words: avian vision, intersexual selection, multiple traits, physiological model.
Received 23 April 2007; revised 21 August 2007; accepted 22 August 2007.