Eumelanin levels in rufous feathers explain plasma testosterone levels and survival in swallows
Eumelanin levels in rufous feathers explain plasma testosterone levels and survival in swallows
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DOI：
10.1002/ece3.4946
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发表时间：
2019-03-01
影响因子：
2.6
通讯作者：
Wakamatsu, Kazumasa
中科院分区：
文献类型：
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作者：
Arai, Emi;Hasegawa, Masaru;Wakamatsu, Kazumasa
基于色素的羽毛颜色及其生理特性吸引了许多研究者来解释这些观赏性状的进化。然而，这些研究假设了主要色素的功能重要性，而忽略了其他次要色素的功能重要性，并且很少有研究关注这些色素的组成。使用褐黑素为基础的羽毛在两个燕子物种，我们研究了分配的两种色素（主要色素，褐黑素，和次要色素，真黑素）的生理特性和生存能力的人口下的自然和性选择。这对于研究褐黑素基羽色的进化是必不可少的。褐黑素和真黑素仅在其发育的初始阶段共享相同的途径，这可能是解开色素分配和羽毛着色的功能重要性的关键。使用谷仓燕子，Hirundo rustica，一个迁徙物种，我们发现，血浆睾酮水平的增加，增加比例的真黑素色素相比，褐黑素色素，但不与褐黑素色素的量，在交配期间。在太平洋燕子Hirundo tahitica（一种非迁徙同类）中，我们发现，在恶劣的冬季天气中，幸存者的真黑色素含量与褐黑色素含量相比，比非幸存者的含量要少，但没有发现可检测到的差异褐黑色素本身。这些结果表明，一个次要的色素，真黑素，事项至少在一些生理措施和活力。由于主要色素，褐黑素，有自己的生理特性，主要和次要色素的组合提供了多种信息的信号接收器，潜在地增强信号功能的褐黑素着色和其多样化的栖息地。
Pigment-based plumage coloration and its physiological properties have attracted many researchers to explain the evolution of such ornamental traits. These studies, however, assume the functional importance of the predominant pigment while ignoring that of other minor pigments, and few studies have focused on the composition of these pigments. Using the pheomelanin-based plumage in two swallow species, we studied the allocation of two pigments (the predominant pigment, pheomelanin, and the minor pigment, eumelanin) in relation to physiological properties and viability in populations under a natural and sexual selection. This is indispensable for studying the evolution of pheomelanin-based plumage coloration. Pheomelanin and eumelanin share the same pathway only during their initial stages of development, which can be a key to unravel the functional importance of pigment allocation and thus of plumage coloration. Using the barn swallow, Hirundo rustica, a migratory species, we found that plasma testosterone levels increased with increasing the proportion of eumelanin pigments compared with pheomelanin pigments, but not with the amount of pheomelanin pigments, during the mating period. In the Pacific swallow Hirundo tahitica, a nonmigratory congener, we found that, during severe winter weathers, survivors had a proportionally smaller amount of eumelanin pigments compared with pheomelanin pigments than that in nonsurvivors, but no detectable difference was found in the pheomelanin pigmentation itself. These results indicated that a minor pigment, eumelanin, matters at least in some physiological measures and viability. Because the major pigment, pheomelanin, has its own physiological properties, a combination of major and minor pigments provides multiple information to the signal receivers, potentially enhancing the signaling function of pheomelanic coloration and its diversification across habitats.