The Importance of Carotenoid Dose in Supplementation Studies with Songbirds
The Importance of Carotenoid Dose in Supplementation Studies with Songbirds
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DOI：
10.1086/684485
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发表时间：
2016-01-01
影响因子：
1.6
通讯作者：
Hill, Geoffrey E.
中科院分区：
文献类型：
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作者：
Koch, Rebecca E.;Wilson, Alan E.;Hill, Geoffrey E.
类胡萝卜素着色是动物观赏性状中研究最多的性状之一。类胡萝卜素着色的许多研究测试类胡萝卜素着色和性能的措施，如免疫能力和氧化状态之间的关联，从类胡萝卜素是有限的资源的前提。这类研究通常涉及在圈养鸟类的饮食中补充类胡萝卜素。然而，在许多情况下，类胡萝卜素的施用量是不合理的，甚至假定类胡萝卜素有限的饮食可能饱和鸟类的系统。为了量化实验中给予的类胡萝卜素量、循环类胡萝卜素水平和沉积到彩色装饰品中的类胡萝卜素量之间的关系，我们对15项已发表的研究进行了荟萃分析，这些研究为七种鸣禽之一补充了类胡萝卜素。我们使用异速生长比例方程来估计每克类胡萝卜素的消费，每个研究的主题，我们使用元回归来评估这种类胡萝卜素剂量的影响，在着色和血浆类胡萝卜素水平之间的差异补充和控制组的鸟类。在考虑了补充时间和种类后，我们观察到类胡萝卜素摄入量与血浆类胡萝卜素水平对补充的反应之间存在显着的正相关。补充类胡萝卜素的存在下，也往往会增加装饰着色的表达，但类胡萝卜素的剂量的大小并没有显着影响如何强烈的着色与补充改变。此外，显色效应大小与血浆类胡萝卜素效应大小没有显着关系。我们还发现研究和物种之间的反应存在显着异质性，用于测量颜色的参数显着影响对补充剂的反应。我们的研究结果强调了进行剂量试验的重要性，以确定什么样的补充水平提供有限的与过剩的类胡萝卜素和测量类胡萝卜素摄入的自然水平的研究物种，以验证适当的补充水平为特定的研究物种和实验设计。
Carotenoid coloration is the one of the most frequently studied ornamental traits in animals. Many studies of carotenoid coloration test the associations between carotenoid coloration and measures of performance, such as immunocompetence and oxidative state, proceeding from the premise that carotenoids are limited resources. Such studies commonly involve supplementing the diets of captive birds with carotenoids. In many cases, however, the amount of carotenoid administered is poorly justified, and even supposedly carotenoid-limited diets may saturate birds' systems. To quantify the relationships among the amount of carotenoids administered in experiments, levels of circulating carotenoids, and quantities of carotenoids deposited into colored ornaments, we performed a meta-analysis of 15 published studies that supplemented carotenoids to one of seven songbird species. We used allometric scaling equations to estimate the per-gram carotenoid consumption of each study's subjects, and we used meta-regression to evaluate the effects of this carotenoid dose on differences in coloration and plasma carotenoid levels between supplemented and control groups of birds. After accounting for supplementation duration and species, we observed a significant positive correlation between carotenoid intake and response of plasma carotenoid level to supplementation. The presence of supplemental carotenoids also tended to increase the expression of ornamental coloration, but the magnitude of the carotenoid dose did not significantly affect how strongly coloration changed with supplementation. Further, coloration effect sizes had no significant relationship with plasma carotenoid effect sizes. We also found significant heterogeneity in responses among studies and species, and the parameters used to measure color significantly affected response to supplementation. Our results emphasize the importance of performing dosage trials to determine what supplementation levels provide limited versus surplus carotenoids and of measuring the natural level of carotenoid intake by the study species to validate the appropriateness of supplementation levels for a particular study species and experimental design.