Morphological basis of glossy red plumage colours

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• 作者：Jean-Pierre Iskandar ; Chad M. Eliason ; Tim Astrop ; Branislav Igic ; Rafael Maia and Matthew D. Shawkey
• 刊名：Biological Journal of the Linnean Society
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：119
• 期：2
• 页码：477-487
• 全文大小：708K
• ISSN：1095-8312

文摘

Brightly coloured feathers, including the brilliant reds produced by carotenoids, are sometimes shiny in appearance. Gloss is a common property of materials and usually arises through specular reflection from smooth, flat surfaces. However, the production of gloss on red feathers has never been examined. In the present study, we compared the optical and structural properties of glossy and matte carotenoid-based red feathers of multiple species to identify the proximate basis for their glossiness. Although specular reflectance did not differ between glossy and matte feathers, diffuse reflectance was lower in glossy than in matte feathers, leading to a higher contrast gloss. Compared to matte feathers, glossy red feathers had thicker barbs with a flatter and more homogeneous morphology, consistent with expectations, as well as thicker outer keratin cortices. Moreover, glossiness was predicted by a principal component regression using these same morphological traits. We demonstrate that the gloss of carotenoid-based red feathers is produced at least in part by a smooth, flattened barb microstructure and an enhanced nanostructure, illustrating a novel colour-producing interaction that neither pigment, nor microstructure could alone attain. How the ecology and evolution of species with glossy red feather differ from those with typical matte red feathers represent rich areas for future study.