Behavioral Ecology Advance Access published online on May 14, 2008
Behavioral Ecology, doi:10.1093/beheco/arn053
Availability of nonpigmentary antioxidant affects red coloration in gulls
a Departamento de Ecoloxía e Bioloxía Animal, Facultade de Bioloxía, Universidade de Vigo, As Lagoas-Marconsende s/n 36310 Vigo, Spain b Departamento de Química Analítica, Nutrición e Bromatoloxía, Facultade de Química, Instituto de Investigacións e Análises Alimentarios, Universidade de Santiago de Compostela, Avenida, das Ciencias s/n 15782 Santiago de Compostela, Spain
Address correspondence to C. Pérez. E-mail: cristobal{at}uvigo.es.
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Abstract |
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Red, orange, and yellow carotenoid-based colorations displayed by fishes and birds may function as honest sexual signals of the bearer's quality. However, the mechanisms underlying the expression of these traits and the information they convey are still controversial. Because carotenoids are antioxidants and carotenoid-based pigmentation is bleached as a consequence of oxidative processes, it has been suggested that the pigmentation may signal antioxidant status. We tested this hypothesis in the yellow-legged gull (Larus michahellis), a seabird that exhibits a carotenoid-based red spot on the lower mandible. The availability of a nonpigmentary antioxidant (i.e., vitamin E) to the gulls was modified before egg laying by means of a supplementary feeding experiment. During the incubation period, breeding pairs were captured to assess the intensity of the color and the size of the red bill spots. We measured the plasma level of lipid peroxidation, total antioxidant capacity, and carotenoids. We found that males that received vitamin E supplements had larger red spot than control birds but that color intensity was not affected by the supplements. Moreover, we found that only those plasma carotenoids involved in the red coloration were affected by the antioxidant supplementation, suggesting an active mechanism to increase red coloration. Overall, our results provide experimental evidence for the hypothesis that carotenoid-based coloration reflects the bearer's antioxidant status in male gulls.
Key words: carotenoids, oxidative stress, sexual selection, trade-off, vitamin E.
Received 13 December 2007; revised 11 April 2008; accepted 15 April 2008.