Best of a bad job or masters of illusion: Do nest light conditions make the eggs of brood parasitic brown‐headed cowbirds ( Molothrus ater ) more similar to the eggs of their hosts?
Best of a bad job or masters of illusion: Do nest light conditions make the eggs of brood parasitic brown‐headed cowbirds ( Molothrus ater ) more similar to the eggs of their hosts?
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最好的坏工作或幻觉大师：巢穴的光照条件是否会使巢中寄生的褐头牛鹂（Molothrus ater）的蛋与宿主的蛋更相似？
DOI：
10.1111/eth.13109
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发表时间：
2020
期刊：
影响因子：
1.7
通讯作者：
Goymann, ed., Wolfgang
中科院分区：
文献类型：
--
作者：
Rutledge, Samantha;Carr, David E.;Hauber, Mark E.;Hanley, Daniel;Goymann, ed., Wolfgang
棕头牛鹂 (Molothrus ater) 是多面性专性寄生寄生虫，在近 300 种鸟类的巢中产卵，并成功寄生超过 100 种宿主物种。牛鹂蛋通常被认为是非模仿的，尽管有些人认为牛鹂蛋类似于其宿主物种的几个蛋。迄今为止，还没有任何调查研究在鸟巢的光线特征和相关观察者的视觉系统的背景下，鸟类感知的牛鹂和不同宿主蛋之间的相似性水平。由于牛鹂会利用多种巢穴类型的物种，宿主会在一系列光线条件下观察这些蛋，这可能会促进或阻碍蛋的辨别。当考虑相关观察者的视觉系统和巢穴的光照条件时，我们发现牛鹂蛋的颜色比非寄主物种的蛋更接近寄主。当宿主感知到自己的蛋和牛鹂的蛋之间存在巨大的色差时，宿主的反应（无论他们接受还是拒绝牛鹂蛋）没有统计学差异。相反，我们发现宿主反应是通过筑巢光照条件促进宿主和牛鹂蛋之间颜色相似性的程度来预测的，因此通常在颜色辨别任务更具挑战性的光照条件下筑巢的宿主更有可能拒绝牛鹂蛋。这表明，即使在没有寄生蛋颜色模仿的情况下，筑巢的光环境也可能选择了一系列牛鹂宿主物种中增强的共同进化的蛋识别能力。
Brown‐headed cowbirds (Molothrus ater) are generalist obligate brood parasites, laying in the nest of nearly 300 avian species, and successfully parasitizing well over 100 host species. Cowbird eggs are generally considered non‐mimetic, although some have suggested that cowbird eggs resemble several of their host species’ eggs. To date, no investigation has examined the level of avian‐perceived similarity between cowbird and diverse host eggs in the contexts of light characteristics at the nest and the visual system of the relevant viewer. Because the cowbird exploits a wide range of species that lay in a variety of nest types, hosts view these eggs under an array of light conditions which could facilitate or hinder egg discrimination. When considering the visual system of the relevant viewers and the light conditions at their nest, we found that the coloration of cowbird eggs was more similar to host than non‐host species’ eggs. Host responses (whether they accept or reject cowbird eggs) were not statistically different when hosts perceived a large chromatic difference between their own eggs and the cowbird's eggs. Instead, we found that host responses were predicted by the degree to which nesting light conditions facilitated color similarity between host and cowbird eggs, such that hosts typically nesting under light conditions where this color discrimination task was more challenging were more likely to reject cowbird eggs. This suggests that the nesting light environment may have selected for increased coevolved egg recognition abilities in a suite of cowbird host species, even in the absence of parasitic egg color mimicry.