Abstract

Whether novel traits involved in animal communication are favored or not by social selection depends on how receivers respond to them. If alternative traits arise at different locations or the same traits are perceived differently, then populations may diverge even when occupying similar environments. Aggressiveness towards bearers of novel versus familiar traits is informative about how male-male competition may drive phenotypic evolution, yet few studies have tested the function of signaling traits in social selection across populations. We assessed the role of a black pectoral band during territorial contests in two allopatric species of Neotropical passerine birds in the genus Arremon either having or lacking this plumage trait. Field experiments using taxidermic mounts and playback of conspecific songs revealed that males of both species were equally aggressive towards phenotypes bearing or lacking a pectoral band. Although evaluating physiological and social costs of bearing alternative traits and assessing female preferences is required to further examine the roles of social and sexual mechanisms in the evolution of plumage and geographic variation, our results indicate that social selection via male-male interactions is an unlikely driver of phenotypic divergence among populations of Arremon.

Significance

Social selection via intrasexual competition for resources may drive phenotypic divergence and population differentation in animals, but few studies have tested predictions of this hypothesis by examining how alternative traits varying geographically are perceived in contexts of male-male competition. We assessed the behavioral response of territorial males in two species of Neotropical songbirds to taxidermic mounts having or lacking a black pectoral band, a geographically variable plumage trait. Irrespective of their own phenotype, males of both species were similarly aggressive to potential intruders bearing or lacking the pectoral band. In contrast with work suggesting male-male interactions may mediate trait evolution, our results indicate that pectoral bands in this system are unlikely targets of social selection via contests in which males compete for territories, and call for studies assessing long-term costs of bearing alternative traits or female choice as selective forces driving phenotypic evolution.

中文翻译：

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地域雄性不区分热带鸣禽物种群中的局部和新型羽毛表型：对社会选择在性状进化中的作用的暗示

摘要

社会选择是否偏爱与动物交流有关的新颖特征，取决于接受者如何回应它们。如果替代性状出现在不同的位置，或者相同的性状被不同地感知，那么即使居住在相似的环境中，种群也可能会发散。对新奇特征和熟悉特征的持有者的侵略性提供了有关雄性竞争如何驱动表型进化的信息，但很少有研究测试信号特征在跨人群的社会选择中的作用。我们评估了Arremon属的两种新异性雀形目鸟类异域物种在领土竞赛中的黑色胸带的作用。具有或缺乏这种羽毛特征。使用动物标本学坐骑和播放同种歌曲的野外实验表明，这两种物种的雄性对具有或没有胸带的表型都具有同等的攻击力。尽管需要评估具有替代性状的生理和社会成本并评估女性偏好，才能进一步检查社会和性机制在羽毛和地理变异演变中的作用，但我们的结果表明，通过男性-男性互动进行社会选择是不太可能的驱动因素Arremon种群间表型差异的研究/ Research。

意义

通过性别内竞争对资源的社会选择可能会推动动物的表型差异和种群分化，但很少有研究通过检验在雄性-雄性竞争的背景下如何感知到地理上变化的替代性状来检验对这一假设的预测。我们评估了两种新热带鸟类中的领地男性对具有或不具有黑色胸带（地理上可变的羽毛特征）的标本动物坐骑的行为反应。不论它们自己的表型如何，这两种物种的雄性对具有或缺乏胸带的潜在入侵者都具有类似的攻击性。与暗示男性与男性互动可能介导性状进化的研究相反，