Do carotenoid-based sexual traits signal the availability of non-pigmentary antioxidants?
Do carotenoid-based sexual traits signal the availability of non-pigmentary antioxidants?
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DOI：
10.1242/jeb.02540
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发表时间：
2006-11-15
影响因子：
2.8
通讯作者：
Sorci, Gabriele
中科院分区：
文献类型：
--
作者：
Bertrand, Sophie;Faivre, Bruno;Sorci, Gabriele
基于类胡萝卜素的信号被认为是男性质量的指标，因为它们必须从饮食中获得，因此可能表明个体收集高质量食物的能力。然而，类胡萝卜素也被认为具有重要的生理功能，如免疫增强剂和抗氧化剂，因此，基于类胡萝卜素的性特征也被认为反映了其携带者的健康和抗氧化状态。这最后一个想法是基于这样的假设，即分配给性信号的类胡萝卜素不再可用于解毒系统。最近，这一假说受到了挑战，理由是抗氧化活性不是类胡萝卜素的主要生物学作用。相反，基于类胡萝卜素的性特征可能表明其他非色素性抗氧化分子的可用性，这些抗氧化分子可能保护类胡萝卜素免受自由基攻击，并使其可用于性广告。我们在斑胸草雀身上验证了这一假设，斑胸草雀是一种雀形目物种，具有基于类胡萝卜素的信号：喙的颜色。我们同时操纵的类胡萝卜素和非色素抗氧化剂（褪黑激素）的饮用水中的可用性。如果褪黑激素的抗氧化特性保护类胡萝卜素氧化，我们预测，补充褪黑激素的鸟类应该比没有补充褪黑激素的鸟类有更红的法案，以及补充类胡萝卜素和褪黑激素的鸟类应该比单独补充类胡萝卜素的鸟类有更红的法案。我们的研究结果与这些预测一致，因为类胡萝卜素和褪黑激素补充剂对票据颜色有相加作用。据我们所知，这是第一个实验证据表明，非色素类抗氧化剂增强类胡萝卜素为基础的性特征的表达。
Carotenoid-based signals are thought to be indicators of male quality because they must be obtained from the diet and might thus indicate the ability of individuals to gather high-quality food. However, carotenoids are also known to have important physiological functions as immunoenhancers and antioxidants, and, as such, carotenoid-based sexual traits have also been suggested to reflect the health and antioxidant status of their bearers. This last idea is based on the hypothesis that carotenoids that are allocated to sexual signals are no longer available for the detoxification system. Recently, this hypothesis has been challenged on the grounds that the antioxidant activity is not the main biological role of carotenoids. Instead, carotenoid-based sexual traits might signal the availability of other non-pigmentary antioxidant molecules that might protect carotenoids from free radical attacks and make them available for sexual advertisements. We tested this hypothesis in the zebra finch, a passerine species with a carotenoid-based signal: the colour of the bill. We simultaneously manipulated the availability of carotenoids and of a non-pigmentary antioxidant (melatonin) in the drinking water. If the antioxidant properties of melatonin protect carotenoids from oxidation, we predict that birds supplemented with melatonin should have redder bills than birds not supplemented with melatonin, and that birds supplemented with carotenoids and melatonin should have redder bills than birds supplemented with carotenoids alone. Our findings are in agreement with these predictions since carotenoid and melatonin supplementation had an additive effect on bill colour. To our knowledge this is the first experimental evidence that a non-pigmentary antioxidant enhances the expression of a carotenoid-based sexual trait.