Macroevolutionary analysis of swallows revives the sight-line hypothesis
Macroevolutionary analysis of swallows revives the sight-line hypothesis
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DOI：
10.1007/s00265-023-03294-x
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发表时间：
2023-02-01
影响因子：
2.3
通讯作者：
Hasegawa，Masaru
中科院分区：
文献类型：
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作者：
Hasegawa，Masaru
引人注目的装饰的进化通常被认为是性选择的结果，但情况可能并非总是如此。其中一个候选者是掠食性动物眼睛前面对比鲜明的浅深色面部颜色图案。视线假说提出，知识和额头之间的对比色有助于跟踪和捕获快速移动的猎物。然而，这一经典假设受到了批评，因此被忽视，原因有几个，包括缺乏控制系统发育惰性的正式统计测试，以及仅仅存在有助于减少眩光的深色面部标记的混杂效应。在这里，我使用系统发育比较方法，在水燕（鸟纲：燕雀科）中测试了视线假说和广泛的替代解释，即性选择假说。我没有发现对海伦犬的前额边界线的性功能的支持，因为前额边界线与性选择指数并不呈正相关。相比之下，我发现视线假说得到了一致的支持。以大型活跃飞行物为食的物种（例如家蝇）比以小型空中浮游生物（例如蠓）为食的物种具有更多对比鲜明的前额边界线。此外，对进化途径的分析为前额边界和猎物大小的正相关进化提供了强有力的支持。当排除缺乏黑暗传说的物种时，这些结果仍然很重要，因此，不仅仅是黑暗传说的存在，对比色图案也可能很重要。据我所知，目前的研究是对视线假说的第一个宏观进化支持。重要的陈述许多掠食性动物的眼睛前面有对比鲜明的浅色和深色图案，或眼线。这种颜色模式可能会适应“视线”，有助于跟踪和捕获快速移动的猎物（视线假设）。几十年来，这一假设一直被忽视，因为眼线被误解为深色面部羽毛的一种形式，有助于减少觅食时的眩光。在这里，我发现视线假说，而不是深色面部颜色标记的眩光减少效应，解释了燕子和马丁鸟（通常有深色面部羽毛）对比浅深色面部颜色图案的宏观进化。眼前的深色羽毛之上的浅色羽毛的进化与捕食快速猎物有着强烈、积极的进化关系。这项研究解释了为什么许多动物有眼线，而不是均匀的深色面部颜色。
The evolution of conspicuous ornamentation is often thought to be the consequence of sexual selection, but this might not always be the case. One such candidate is the contrasting pale-dark facial color patterns in front of eyes in predatory animals. The sight-line hypothesis proposes that the contrasting color between lore and forehead assists in tracking and capturing a fast-moving prey. However, this classic hypothesis has been criticized and thus ignored for several reasons including lack of formal statistical testing controlling for phylogenetic inertia and the confounding effect of the mere presence of dark facial markings that help reduce glare. Here, using a phylogenetic comparative approach, I tested the sight-line hypothesis and a widespread alternative explanation, the sexual selection hypothesis, in hirundines (Aves: Hirundinidae). I found no support for a sexual function of lore-forehead borderline in hirundines, because lore-forehead borderline was not positively related to indices of sexual selection. In contrast, I found consistent support for the sight-line hypothesis. Species foraging on large active fliers (e.g., house flies) had more contrasting lore-forehead borderline than species foraging on small aerial planktons (e.g., midges). Furthermore, an analysis of evolutionary pathways provided a strong support for positively correlated evolution of lore-forehead borderline and prey size. These results remained significant when excluding species that lack dark lores and, thus, not mere presence of dark lores but contrasting color patterns may be important. To my knowledge, the current study is the first macroevolutionary support for the sight-line hypothesis.Significant statementMany predatory animals have contrasting pale and dark color pattern, or eyeline, in front of eyes. This color pattern might be adaptive as a “sight-line”, which can aid in tracking and capturing a fast-moving prey (sight-line hypothesis). This hypothesis has been ignored for decades, because eyeline has been misinterpreted as a form of dark facial feathers, which can aid in glare reduction at foraging. Here, I found that the sight-line hypothesis, but not glare-reducing effect of dark facial color marking, explained the macroevolution of contrasting pale-dark facial color patterns in swallows and martins, which commonly have dark facial feathers. The evolution of pale feathers above dark feathers in front of eyes had strong, positive evolutionary relationships with foraging on speedy preys. This study explains why many animals have eyelines instead of uniformally dark facial coloration.