Karu Ulvi, Saks Lauri, Hõrak Peeter
Institute of Zoology and Hydrobiology, Tartu University, Vanemuise 46, 51014 Tartu, Estonia.
Physiol Biochem Zool. 2007 Nov-Dec;80(6):663-70. doi: 10.1086/521084. Epub 2007 Sep 5.
Carotenoid-based plumage coloration of birds has been hypothesized to honestly reflect individual quality, either because carotenoids are difficult to acquire via food or because of a trade-off in allocation of carotenoids between maintenance and signaling functions. We tested whether differential foraging ability is a necessary precondition for maintaining individual differences in carotenoid-based plumage coloration in male greenfinches (Carduelis chloris). Wild-caught birds were brought into captivity, where half of them were supplemented with carotenoids while the other half was maintained on a carotenoid-poor diet. Color of the yellow parts of tail feathers, grown under natural conditions, was compared with that of the replacement feathers, grown in captivity. Carotenoid supplementation increased feather chroma (saturation). Color of wild-grown feathers significantly correlated with the color of lab-grown feathers. This result demonstrates the existence of a significant component of variation in carotenoid coloration, which reflects physiological qualities or genetic differences among individuals independent of foraging ability. Among both experimental groups, plasma carotenoid concentration during feather growth strongly correlated with chroma of the feathers grown in captivity. This indicates that carotenoid-based plumage coloration can reveal circulating carotenoid levels over a very wide range of concentrations, suggesting the ample signaling potential of such a mechanism.
基于类胡萝卜素的鸟类羽毛颜色被认为能够真实反映个体质量，这要么是因为类胡萝卜素难以通过食物获取，要么是由于在维持功能和信号功能之间类胡萝卜素分配存在权衡。我们测试了不同的觅食能力是否是维持雄性绿雀（绿雀属）基于类胡萝卜素的羽毛颜色个体差异的必要前提条件。将野生捕获的鸟类圈养起来，其中一半补充类胡萝卜素，另一半则以缺乏类胡萝卜素的食物饲养。将在自然条件下生长的尾羽黄色部分的颜色与在圈养环境中生长的替换羽毛的颜色进行比较。补充类胡萝卜素增加了羽毛的色度（饱和度）。野生生长羽毛的颜色与实验室生长羽毛的颜色显著相关。这一结果表明，类胡萝卜素颜色变化中存在一个显著成分，它反映了个体之间独立于觅食能力的生理特性或基因差异。在两个实验组中，羽毛生长期间血浆类胡萝卜素浓度与圈养环境中生长的羽毛色度密切相关。这表明基于类胡萝卜素的羽毛颜色能够在非常广泛的浓度范围内揭示循环类胡萝卜素水平，暗示了这种机制具有充足的信号传递潜力。
