How and why certain groups become speciose is a key question in evolutionary biology. Novel traits that enable diversification by opening new ecological niches are likely important mechanisms. However, ornamental traits can also promote diversification by opening up novel sensory niches and thereby creating novel inter-specific interactions. More specifically, ornamental colors may enable more precise and/or easier species recognition and may act as key innovations by increasing the number of species-specific patterns and promoting diversification. While the influence of coloration on diversification is well-studied, the influence of the mechanisms that produce those colors (e.g., pigmentary, nanostructural) is less so, even though the ontogeny and evolution of these mechanisms differ. We estimated a new phylogenetic tree for 121 sunbird species and combined color data of 106 species with a range of phylogenetic tools to test the hypothesis that the evolution of novel color mechanisms increases diversification in sunbirds, one of the most colorful bird clades. Results suggest that: (1) the evolution of novel color mechanisms expands the visual sensory niche, increasing the number of achievable colors, (2) structural coloration diverges more readily across the body than pigment-based coloration, enabling an increase in color complexity, (3) novel color mechanisms might minimize trade-offs between natural and sexual selection such that color can function both as camouflage and conspicuous signal, and (4) despite structural colors being more colorful and mobile, only melanin-based coloration is positively correlated with net diversification. Together, these findings explain why color distances increase with an increasing number of sympatric species, even though packing of color space predicts otherwise.

中文翻译：

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多种颜色机制的进化与太阳鸟 （Nectariniidae） 的多样化相关


某些群体如何以及为什么变得物种化是进化生物学中的一个关键问题。通过开辟新的生态位实现多样化的新性状可能是重要的机制。然而，观赏性状也可以通过开辟新的感官生态位来促进多样化，从而创造新的种间互动。更具体地说，装饰色可以实现更精确和/或更容易的物种识别，并可能通过增加物种特异性图案的数量和促进多样化来发挥关键创新的作用。虽然着色对多样化的影响得到了很好的研究，但产生这些颜色的机制（例如，色素、纳米结构）的影响较小，即使这些机制的个体发育和进化不同。我们估计了 121 种太阳鸟物种的新系统发育树，并将 106 种的颜色数据与一系列系统发育工具相结合，以检验新颜色机制的进化增加了太阳鸟的多样性的假设，太阳鸟是色彩最丰富的鸟类分支之一。结果表明：（1） 新型色彩机制的进化扩大了视觉感官生态位，增加了可实现的颜色数量，（2） 结构着色比基于色素的着色更容易在全身发散，从而增加了颜色的复杂性，（3） 新颖的颜色机制可以最大限度地减少自然选择和性选择之间的权衡，使颜色既可以用作伪装，也可以用作显眼信号， （4） 尽管结构色更加丰富多彩和可移动，但只有基于黑色素的着色与净多样化呈正相关。 总之，这些发现解释了为什么颜色距离随着同域物种数量的增加而增加，即使颜色空间的堆积预测并非如此。