Museum of Natural Science and Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, 70803.
Evolution. 2019 Apr;73(4):704-719. doi: 10.1111/evo.13707. Epub 2019 Mar 14.
Both natural and sexual selection are thought to affect the evolution of bird color. Most studies of the topic have focused on sexually dichromatic taxa and showy plumages, which are expected to be more influenced by social selection and usually result in increased conspicuousness. However, many bird clades display dull brown or gray plumages that vary greatly in brightness (lightness), but little in hue (shade). Here, we examine the macroevolution of brightness in one such clade, the Furnariida. We make comparisons across light environments, body parts, monochromatic lineages, and each sex of dichromatic lineages. We found that support for models including light environments is greater for the dorsum than for the venter, and that brightness evolution is more constrained in the former than in the latter. Plumages in this clade have evolved to be darker in darker habitats, consistent with natural selection for increased crypsis. Finally, the features of brightness macroevolution are broadly similar across the sexes of the dichromatic clade, challenging the view that sexual dichromatism is driven by different evolutionary processes acting in each sex. We conclude that, in the Furnariida, light environments and dorsal-ventral variation are more important than sex as axes of color evolution.
自然选择和性选择被认为都会影响鸟类颜色的进化。大多数关于这个主题的研究都集中在性二色性分类群和鲜艳的羽毛上，这些分类群预计会受到更多的社会选择的影响，通常会导致更高的显著性。然而，许多鸟类支系显示出暗淡的棕色或灰色羽毛，其亮度（明度）差异很大，但色调（阴影）差异很小。在这里，我们研究了一个这样的支系， Furnariida 的亮度的宏观进化。我们在不同的光照环境、身体部位、单色谱系以及二色性谱系的每一个性别之间进行了比较。我们发现，包括光照环境在内的模型得到的支持程度在背部比在腹部更大，而且前者的亮度进化比后者受到更多的限制。这个支系的羽毛在较暗的栖息地进化得更暗，这与自然选择增加隐蔽性是一致的。最后，在二色性支系的两性中，亮度宏观进化的特征大致相似，这挑战了性二色性是由两性中不同的进化过程驱动的观点。我们的结论是，在 Furnariida 中，光照环境和背腹变化比性别更重要，是颜色进化的轴线。
