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 colours 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 colouration on diversification is well-studied, the influence of the mechanisms that produce those colours (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 colour data of 106 species with a range of phylogenetic tools to test the hypothesis that the evolution of novel colour mechanisms increases diversification in sunbirds, one of the most colourful bird clades. Results suggest that (1) the evolution of novel colour mechanisms expands the visual sensory niche, increasing the number of achievable colours. (2) Structural colouration diverges more readily across the body than pigment-based colouration, enabling an increase in colour complexity. (3) Novel colour mechanisms might minimize trade-offs between natural and sexual selection such that colour can function both as camouflage and conspicuous signal. (4) Despite structural colours being more colourful and mobile, only melanin-based colouration is positively correlated with net diversification. Together, these findings explain why colour distances increase with increasing number of sympatric species, even though packing of colour space would predict 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何变得特殊是进化生物学的一个关键问题。通过开辟新的生态位来实现多样化的新特征可能是重要的机制。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，从而创造新的种间相互作用。更具体地说，装饰性颜色可以实现更精确和/或更容易的物种识别，并且可以通过增加物种特定图案的数量和促进多样化来充当关键创新。虽然着色对多样化的影响已得到充分研究，但产生这些颜色的机制（例如色素、纳米结构）的影响却较少研究，即使这些机制的个体发育和进化不同。我们估计了 121 个太阳鸟物种的新系统发育树，并将 106 个物种的颜色数据与一系列系统发育工具结合起来，以检验新的颜色机制的进化增加了太阳鸟（色彩最鲜艳的鸟类分支之一）的多样性的假设。结果表明：（1）新颖颜色机制的演变扩大了视觉感官生态位，增加了可实现的颜色数量。 (2) 结构着色比基于颜料的着色更容易在身体上发散，从而增加颜色的复杂性。 （3）新颖的颜色机制可能会最大限度地减少自然选择和性选择之间的权衡，从而使颜色既可以起到伪装作用，又可以起到显着信号的作用。 (4) 尽管结构颜色更加丰富多彩和流动，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，尽管颜色空间的堆积会预测相反的情况。