Large, conspicuous traits frequently evolve despite increased predator attention, but in some cases, specifically to attract attention. Sexually selected traits provide some of the clearest examples of elaboration, yet natural selection can also be a powerful driver. The matador bug, Anisoscelis alipes (Hemiptera: Coreidae), has large, colorful flags on its legs that, unlike many other coreid species, are not used in reproductive competition. We hypothesized that these flags either a) warn predators of chemical defense, or b) deflect predatory attack to the removable hindlegs. We pitted matador bugs with or without flags and crickets (Acheta domesticus) with or without bug flags experimentally attached to their legs, against live motmot bird predators (Momotus subrufescens and Electron platyrhynchum). Contrary to the deflection hypothesis, almost none of the predatory strikes were directed at hindleg flags. Instead, we found support for the aposematism hypothesis: matador bug flags reduced attacks on palatable crickets, but were unnecessary to prevent predator attack against matador bugs. Palatability studies with naïve chicks (Gallus gallus) further supported a chemical defense hypothesis. Thus, these elaborate hindleg flags serve an aposematic anti-predator function, but in their absence, birds use alternative cues. These findings add to our understanding of the role of predation in driving the evolution of elaborate morphological structures.

中文翻译：

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斗牛士虫精致的旗帜阻止鸟类掠食者

尽管捕食者的注意力不断增加，但在某些情况下，大型、显眼的特征经常会进化，特别是为了吸引注意力。性选择特征提供了一些最清晰的例子，但自然选择也可以是一个强大的驱动力。斗牛士 Anisoscelis alipes（半翅目：Coreidae）的腿上有巨大的彩色旗帜，与许多其他斗牛类物种不同，它不用于繁殖竞争。我们假设这些旗帜要么a）警告掠食者化学防御，要么b）将掠夺性攻击转向可移动的后腿。我们将带或不带旗的斗牛士蝽和腿上带或不带虫旗的蟋蟀（Acheta Domesticus）与活的鸟类掠食者（Momotus subrufescens 和 Electron platyrhynchum）进行实验。与偏转假说相反，几乎没有一次掠夺性攻击是针对后腿旗的。相反，我们发现了对警戒假设的支持：斗牛士臭虫旗帜减少了对可口蟋蟀的攻击，但对于防止捕食者对斗牛士臭虫的攻击是不必要的。对幼鸡（Gallus gallus）的适口性研究进一步支持了化学防御假说。因此，这些精心设计的后腿旗帜具有警戒性的反捕食者功能，但在没有这些旗帜的情况下，鸟类会使用其他线索。这些发现增加了我们对捕食在驱动复杂形态结构进化中的作用的理解。