Signal evolution and morphological complexity in hummingbirds (Aves: Trochilidae)

Understanding how animal signals are produced is critical for understanding their evolution because complexity and modularity in the underlying morphology can affect evolutionary patterns. Hummingbird feathers show some of the brightest and most iridescent colors in nature. These are produced by optically complex stacks of hollow, platelet-shaped organelles called melanosomes. Neither how these morphologies produce colors nor their evolution has been systematically studied. We first used nanoscale morphological measurements and optical modeling to identify the physical basis of color production in 34 hummingbird species. We found that, in general, the melanosome stacks function as multilayer reflectors, with platelet thickness and air space size explaining variation in hue (color) and saturation (color purity). Additionally, light rays reflected from the outer keratin surface interact with those reflected by small, superficial melanosomes to cause secondary reflectance peaks, primarily ...

解析动物信号的产生机制，对于理解其演化过程至关重要，因为生物体底层形态结构的复杂性与模块化特征，会对演化模式产生影响。蜂鸟羽毛拥有自然界中最为鲜亮绚烂的虹彩色泽，这类色彩由光学结构复杂的空心片状细胞器堆叠而成，该细胞器被称为黑素体（melanosome）。目前尚未有研究系统解析此类形态结构的显色机制，也未对其演化历程展开系统性探讨。本研究首先通过纳米级形态测量与光学建模技术，解析了34种蜂鸟的显色物理基础。研究发现，总体而言，黑素体堆叠结构发挥着多层反射器的功能，而片状结构的厚度与空气间隙尺寸，可解释色调（色彩）与饱和度（色纯度）的变化差异。此外，从羽毛外层角蛋白表面反射的光线，与浅层小型黑素体反射的光线发生相互作用，进而产生次级反射峰，主要……