Fitze Patrick S, Kölliker Mathias, Richner Heinz
University Pierre and Marie Curie-Centre National de la Recherche Scientifique, Laboratoire d'Ecologie, 7, quai Saint Bernard, Case 237, F-75252 Paris Cedex 05, France.
Evolution. 2003 Jan;57(1):144-50. doi: 10.1111/j.0014-3820.2003.tb00222.x.
Carotenoids cannot be synthesized by birds and thus have to be ingested with food, suggesting that carotenoid-based plumage coloration is environmentally determined. However signaling functions ascribed to plumage imply that plumage coloration is the outcome of an evolutionary process based on genetic variation. By means of a cross-fostering design we show significant effects of both a common rearing environment and the brood from which a nestling originally came from (common origin) on the plumage coloration of nestling great tits (Parus major). This demonstration of origin-related variation in carotenoid-based plumage coloration suggests that the observed variation of the trait has a partial genetic basis. Consistent with environmental determination of this trait, we also found a significant positive correlation between the color saturation of nestlings and their foster-father's plumage. There was no significant correlation between nestling plumage coloration and the food quantity provided to the nestlings by the male, the female, or both parents. This suggests that the nestling-foster father correlation arises by the carotenoid quantity ingested rather than the food quantity per se. No significant nestling-true father correlation was found, which suggests that nestling plumage coloration did not indirectly evolve due to sexual selection. Consistent with this result there was no significant correlation between the nestling's plumage color and its coloration as a breeding adult the following year, suggesting that nestling plumage color is a different trait than the first year plumage.
鸟类无法合成类胡萝卜素，因此必须通过食物摄取，这表明基于类胡萝卜素的羽毛颜色是由环境决定的。然而，赋予羽毛的信号功能意味着羽毛颜色是基于遗传变异的进化过程的结果。通过交叉寄养设计，我们发现共同饲养环境以及雏鸟最初来自的窝雏（共同起源）对大山雀（Parus major）雏鸟的羽毛颜色都有显著影响。这种基于类胡萝卜素的羽毛颜色与起源相关变异的证明表明，观察到的性状变异有部分遗传基础。与该性状由环境决定相一致，我们还发现雏鸟的颜色饱和度与其养父的羽毛之间存在显著正相关。雏鸟的羽毛颜色与雄性、雌性或双亲提供给雏鸟的食物量之间没有显著相关性。这表明雏鸟与养父的相关性是由摄入的类胡萝卜素量而非食物量本身引起的。未发现雏鸟与亲生父亲之间有显著相关性，这表明雏鸟的羽毛颜色并非因性选择而间接进化。与这一结果一致，雏鸟的羽毛颜色与其次年作为繁殖成年鸟时的颜色之间没有显著相关性，这表明雏鸟的羽毛颜色与第一年的羽毛是不同的性状。
