How hollow melanosomes affect iridescent colour production in birds
How hollow melanosomes affect iridescent colour production in birds
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DOI：
10.1098/rspb.2013.1505
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发表时间：
2013-09-22
影响因子：
4.7
通讯作者：
Shawkey, Matthew D.
中科院分区：
文献类型：
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作者：
Eliason, Chad M.;Bitton, Pierre-Paul;Shawkey, Matthew D.
发展的限制和权衡可能会限制多样性，但生物体不断进化出形态创新，通过扩大特征的范围和功能来克服这些限制。鸟类中的彩虹色通常是由在羽毛微囊内组织成纳米结构阵列的含黑色素的细胞器（黑素体）产生的。数组类型的变化（e. G.多层膜和光子晶体（PC）对羽毛颜色有显著的影响，但对黑素体形状变化的光学后果仍然知之甚少。在这里，我们使用了分光光度法，实验和理论方法相结合，以测试黑素体中空，主要限于鸟类的形态创新，影响羽毛颜色。光学分析的六角形密排阵列的空心黑素体在两个物种，野生火鸡（Meleagris gallopavo）和紫背椋鸟（Cinnyricinclus leucogaster），表明它们的功能作为二维PC。结合一个更大的数据集和光学建模表明，与固体黑素体相比，中空的黑素体允许鸟类产生不同的颜色，具有相同的能量有利的，紧密堆积的配置。这些数据表明，形态上的新奇至少部分地使鸟类实现了巨大的形态和颜色多样性。
Developmental constraints and trade-offs can limit diversity, but organisms have repeatedly evolved morphological innovations that overcome these limits by expanding the range and functionality of traits. Iridescent colours in birds are commonly produced by melanin-containing organelles (melanosomes) organized into nanostructured arrays within feather barbules. Variation in array type (e. g. multilayers and photonic crystals, PCs) is known to have remarkable effects on plumage colour, but the optical consequences of variation in melanosome shape remain poorly understood. Here, we used a combination of spectrophotometric, experimental and theoretical methods to test how melanosome hollowness-a morphological innovation largely restricted to birds-affects feather colour. Optical analyses of hexagonal close-packed arrays of hollow melanosomes in two species, wild turkeys (Meleagris gallopavo) and violet-backed starlings (Cinnyricinclus leucogaster), indicated that they function as two-dimensional PCs. Incorporation of a larger dataset and optical modelling showed that, compared with solid melanosomes, hollow melanosomes allow birds to produce distinct colours with the same energetically favourable, close-packed configurations. These data suggest that a morphological novelty has, at least in part, allowed birds to achieve their vast morphological and colour diversity.