Browsing by Author "Saino, Nicola"

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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.
Maternal Effects Mediated by Egg Quality in the Yellow-Legged Gull Larus Michahellis in Relation To Laying Order and Embryo Sex
(Bmc, 2011) Rubolini, Diego; Romano, Maria; Navara, Kristen J.; Karadas, Filiz; Ambrosini, Roberto; Caprioli, Manuela; Saino, Nicola
Background: Maternal effects mediated by egg size and quality may profoundly affect offspring development and performance, and mothers may adjust egg traits according to environmental or social influences. In avian species, context-dependency of maternal effects may result in variation in egg composition, as well as in differential patterns of covariation among selected egg components, according to, for example, position in the laying sequence or offspring sex. We investigated variation in major classes of egg yolk components (carotenoids, vitamins and steroid hormones) in relation to egg size, position in the laying sequence and embryo sex in clutches of the Yellow-legged Gull (Larus michahellis). We also investigated their covariation, to highlight mutual adjustments, maternal constraints or trade-offs in egg allocation. Results: Laying sequence-specific patterns of allocation emerged: concentration of carotenoids and vitamin E decreased, while concentrations of androgens increased. Vitamin A, estradiol and corticosterone did not show any change. There was no evidence of sex-specific allocation or covariation of yolk components. Concentrations of carotenoids and vitamins were positively correlated. Egg mass decreased along the laying sequence, and this decrease was negatively correlated with the mean concentrations of carotenoids in clutches, suggesting that nutritionally constrained females lay low quality clutches in terms of carotenoid content. Finally, clutches with smaller decline in antioxidants between first-and last-laid eggs had a larger increase in yolk corticosterone, suggesting that a smaller antioxidant depletion along the laying sequence may entail a cost for laying females in terms of increased stress levels. Conclusions: Since some of the analyzed yolk components (e. g. testosterone and lutein) are known to exert sex-specific phenotypic effects on the progeny in this species, the lack of sex-specific egg allocation by mothers may either result from trade-offs between contrasting effects of different egg components on male and female offspring, or indicate that sex-specific traits are controlled primarily by mechanisms of sexual differentiation, including endogenous hormone production or metabolism of exogenous antioxidants, during embryonic development.
Yolk Vitamin E Positively Affects Prenatal Growth but Not Oxidative Status in Yellow-Legged Gull Embryos
(Oxford Univ Press, 2018) Parolini, Marco; Possenti, Cristina Daniela; Karadas, Filiz; Colombo, Graziano; Romano, Maria; Caprioli, Manuela; Saino, Nicola
Parental effects occur whenever the phenotype of parents or the environment that they experience influences the phenotype and fitness of their offspring. In birds, parental effects are often mediated by the size and biochemical quality of the eggs in terms of maternally transferred components. Exogenous antioxidants are key egg components that accomplish crucial physiological functions during early life. Among these, vitamin E plays a vital role during prenatal development when the intense metabolism accompanying rapid embryo growth results in overproduction of pro-oxidant molecules. Studies of captive birds have demonstrated the positive effect of vitamin E supplementation on diverse phenotypic traits of hatchling and adult individuals, but its effects on embryo phenotype has never been investigated neither in captivity nor under a natural selection regime. In the present study, we experimentally tested the effect of the in ovo supplementation of vitamin E on morphological traits and oxidative status of yellow-legged gull (Larus michahellis) embryos. The supplementation of vitamin E promoted somatic growth in embryos soon before hatching, but did not affect their oxidative status. Our results suggest that maternally transferred vitamin E concentrations are optimized to prevent imbalances of oxidative status and the consequent raise of oxidative damage in yellow-legged gull embryos during prenatal development.