Browsing by Author "Biard, Clotilde"

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Is Oxidative Status Influenced by Dietary Carotenoid and Physical Activity After Moult in the Great Tit (Parus Major)
(Company Biologists Ltd, 2015) Vaugoyeau, Marie; Decenciere, Beatriz; Perret, Samuel; Karadas, Filiz; Meylan, Sandrine; Biard, Clotilde
In the context of sexual and natural selection, an allocation trade-off for carotenoid pigments may exist because of their obligate dietary origin and their role both in the antioxidant and immune systems and in the production of coloured signals in various taxa, particularly birds. When birds have expended large amounts of carotenoids to feather growth such as after autumn moult, bird health and oxidative status might be more constrained. We tested this hypothesis in a bird species with carotenoid-based plumage colour, by manipulating dietary carotenoids and physical activity, which can decrease antioxidant capacity and increase reactive oxygen metabolite (ROM) concentration. Great tits were captured after moult and kept in aviaries, under three treatments: physical handicap and dietary supplementation with carotenoids, physical handicap and control diet, and no handicap and control diet. We measured plasma composition (antioxidant capacity, ROM concentration, and vitamin A, vitamin E and total carotenoid concentrations), immune system activation (blood sedimentation) and stress response (heterophil/lymphocyte ratio) and predicted that handicap treatment should influence these negatively and carotenoid supplementation positively. Coloration of yellow feathers was also measured. Carotenoid supplementation increased total plasma carotenoid concentration, decreased feather carotenoid chroma and marginally increased ROM concentration. Handicap increased blood sedimentation only in males but had no clear influence on oxidative stress, which contradicted previous studies. Further studies are needed to investigate how physical activity and carotenoid availability might interact and influence oxidative stress outside the moult period, and their combined potential influence on attractiveness and reproductive investment later during the breeding season.
Maternal Effects and Changing Phenology of Bird Migration
(inter-research, 2011) Moller, Anders Pape; Biard, Clotilde; Karadas, Filiz; Rubolini, Diego; Saino, Nicola; Surai, Peter F.
Recent changes in migration distances and propensity for migration associated with climate change have suggested that these traits can evolve rapidly. Part of this rapid response to selection may be due to maternal effects that facilitate changes in the underlying physiology of migration. We hypothesize that exposure to large amounts of antioxidants in the egg will facilitate assimilation and metabolism of dietary antioxidants later in life, thereby allowing offspring to better cope with extreme strenuous exercise such as the bursts of rapid migration shown during spring migration. We tested the relationship between temporal change in mean arrival date of migratory birds since 1960 and concentrations of 2 antioxidants in the eggs of 14 species of birds. Only egg concentration of vitamin E was a significant predictor of advancement in spring arrival date. Furthermore, we experimentally manipulated egg content of vitamin E in barn swallows Hirundo rustica and subsequently recorded arrival date of yearling male recruits. Arrival date advanced significantly by > 1 standard deviation due to treatment, providing experimental evidence for a relationship between egg concentration of vitamin E and subsequent migration behavior. These results are consistent with the hypothesis that maternal effects have played an important role in the evolution of bird migration.
Maternal Effects Mediated by Antioxidants and the Evolution of Carotenoid-Based Signals in Birds
(Univ Chicago Press, 2009) Biard, Clotilde; Gil, Diego; Karadas, Filiz; Saino, Nicola; Spottiswoode, Claire N.; Surai, Peter F.; Moller, Anders P.
Bright yellow to red signals used in mate choice or intrasexual competition are based on carotenoid pigments that are hypothesized to be traded between physiological functions and coloration. These signals have recently been shown to be influenced by maternal effects. Indeed, yolk-derived carotenoids are essential for embryos to develop efficient carotenoid metabolism in posthatching life. Maternal effects facilitate adaptation to environmental variability and influence the evolution of phenotypic traits such as secondary sexual signals. Here we propose that maternal investment in yolk carotenoids promotes the evolution of carotenoid-based ornaments. We conducted a comparative analysis of lipid-soluble antioxidants (carotenoids and vitamins A and E) in the eggs of 112 species of bird. Species with large clutch sizes deposited higher yolk concentrations of the three antioxidants. There was a significant positive relationship between yolk carotenoids and the expression of male carotenoid-based signals, but not between yolk carotenoids and sexual dichromatism in these signals. These relationships were specific to carotenoids, as they were not found for vitamins A and E. This provides evidence consistent with the hypothesis that maternal effects mediated by yolk carotenoids play a role in the evolution of carotenoid-based signals as a response to sexual selection, likely based on organizational effects of carotenoids during embryo development.