Conspicuous coloured displays from ultraviolet to bright red have been documented in many species throughout the animal kingdom. These colours often occur as sexual signals and can be incorporated into different types of integuments (e.g. scales, feathers, skin). Two main mechanisms are known to produce coloured integuments: pigmentation and tissue structure. Although pigmental and structural coloration are separate mechanisms and can occur independently, some coloured displays might emerge from a combination of both. Here, we demonstrate, using biochemical, optical and morphological methodologies, that the yellow coloration of the skin located around the eye of Common (Indian) Mynas (Acridotheres tristis) is produced by both light-reflecting nanostructures and light-absorbing carotenoid pigments. Our analysis confirms that nanostructured collagen in the avian dermis work in combination with carotenoid pigments to produce vivid integumentary colours. Identifying the mechanisms behind the production of a coloured signal provides a basis for predicting how a signal’s function might be influenced by environmental factors such as fledgling nutrition.

中文翻译：

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组织结构有助于在普通八哥中产生彩色皮肤显示

在整个动物王国的许多物种中都记录了从紫外线到鲜红色的显眼彩色显示。这些颜色通常作为性信号出现，可以融入不同类型的外皮（例如鳞片、羽毛、皮肤）。已知产生有色珠被的两种主要机制：色素沉着和组织结构。尽管色素和结构着色是独立的机制并且可以独立发生，但一些彩色显示可能是两者的结合。在这里，我们使用生化、光学和形态学方法证明，位于普通（印度）八哥（Acridotheres tristis）眼睛周围的皮肤的黄色是由反光纳米结构和吸光类胡萝卜素色素产生的。我们的分析证实，禽类真皮中的纳米结构胶原蛋白与类胡萝卜素色素结合产生鲜艳的外皮颜色。确定产生有色信号背后的机制，为预测信号的功能如何受到环境因素（如新生营养）的影响奠定了基础。