CAREER: Song and Plumage in the House Finch: A Study of Signal Content in a Multiple-Signal System

鲜艳的颜色和优美的歌声是鸟类最显著的特征，但这些特征给进化生物学家带来了一个悖论。这些看起来浪费能量、让个体暴露在捕食者面前的花哨特征，是如何通过自然选择进化而来的呢？自然选择应该是促进生存和繁殖的过程。对于这个问题，普遍接受的答案是，这种装饰性特征是通过性选择产生的，这个过程通过吸引配偶或保护配偶来促进获得配偶。在观赏性状的进化过程中，雌性择偶已被证明是一个重要的选择因素，但雌性为什么要选择这些性状呢？对这个谜题的一种解释是，装饰性特征是男性品质的诚实信号。雌性会选择拥有发达装饰物的雄性，从而选择比平均水平更好的雄性。然而，情节更加复杂的是，大多数动物物种都有多种观赏特征，而不是一种。例如，大多数种类的鸣禽都有彩色的羽毛和歌声。这项研究将研究雀鸟的鸣叫和色彩斑斓的羽毛的功能，雀鸟是一种遍布美国大陆的常见的后院鸟类。研究将测试雌性雀鸟从不同的观赏特征中获得关于雄性品质的不同信息。家雀的彩色羽毛是类胡萝卜素的结果，这种色素必须从鸟类的饮食中获得。因此，羽毛的亮度是雄性羽毛生长时营养状况的一个功能。人们对歌曲发育的控制知之甚少，但它也可能依赖于营养。这项工作的重点是男性素质的两个指标：抗病性和亲代努力。通过对圈养鸟类进行的实验和对野生鸟类的观察，该研究将确定雄性家雀的鸣叫和观赏羽毛颜色与两种不同类型疾病的关系：球虫病（一种慢性肠道寄生虫）和结膜炎（一种快速发作的眼睛和上呼吸道细菌感染）。预测是，在展示时产生的歌声将是一个较好的指标，短期内快速作用的疾病。相比之下，羽毛的生长时间为6周，在展出前的几个月，可以更好地预测慢性感染。鸣声和羽毛也可能传达雄性繁殖后代能力的不同信息。该研究将是首次同时研究多种观赏性状的功能，并将为动物的性选择和观赏性状的进化过程提供新的见解。雄性动物身上引人注目的装饰性特征可能会向雌性传递关于未来伴侣的信息，这是一个直觉上吸引人的假设，许多学生（从广义上讲，包括高中生、科学教师、本科生和成人教育学生）都觉得很有说服力。该研究项目将以教育为重点，包括前面提到的学生群体的参与。家雀是一个理想的物种，旨在向学生介绍野外生物学的研究-他们是小，温顺，容易捕捉，有明亮的颜色，容易量化，习惯与人相处，并在校园显眼的地方筑巢。此外，在美国几乎每个校园都有家雀的踪迹，本研究的一部分还将与高中教师一起开展科学练习，让学生体验真正的科学调查的挑战和兴奋。

IBN-9722171 Hill Bright colors and beautiful song are among the most conspicuous features of birds, but these traits pose a paradox for evolutionary biologists. How could such gaudy traits, which seem to waste energy and expose individuals to predators, have evolved by natural selection, a process that should promote survivorship and reproduction? The generally accepted answer to this question is that such ornamental traits arose through sexual selection, a process that promotes access to mates either through mate attraction or mate defense. Female mate choice has been shown to be an important selective agent in the evolution of ornamental traits, but why should females choose such traits? One explanation for this riddle is that ornamental traits serve as honest signals of male quality. By choosing males with well-developed ornaments, females choose better-than-average males. The plot thickens further, though, in that most species of animals have not one but multiple ornamental traits. For instance, most species of songbirds have both colorful plumage and song. This research will study the function of song and colorful plumage in the House Finch, a common backyard bird found throughout the contintental U.S. Studies will test the idea that female House Finches gain different information about male quality from different ornamental traits. Colorful plumage in the House Finch is a result of carotenoid pigments, which birds must obtain from their diet. Thus, plumage brightness is a function of the nutritional condition of males at the time when feathers are grown. The control of song development is less well understood, but it may also be dependent on nutrition. The focus of this work is on two measures of male quality: disease resistance and parental effort. Using a combination of experiments conducted with captive birds and observations of wild birds, the study will determine how song and ornamental plumage coloration of male House Finches relate to two different types of disease: coccidia, a chronic intestinal parasite, and conjunctivitis, a bacterial infection of the eye and upper respiratory system with rapid onset. The prediction is that song, which is produced at the time of display, will be a better indicator of fast- acting disease of short duration. In contrast, plumage, which is grown over a six-week period, months before it is used in display, will be a better predictor of chronic infection. Song and plumage may also convey different information about the ability of males to provision young. This research will be among the first to simultaneously investigate the function of multiple ornamental traits, and will provide new insight into the process of sexual selection and the evolution of ornamental traits in animals. The idea that conspicuous ornamental traits in male animals might convey information about prospective mates to females is an intuitively appealing hypothesis that many students (in the broad sense - including high school students, science teachers, undergraduates and adult education students) find compelling. The research project will incorporate an educational focus involving participation by the previously-mentioned student populations. The House Finch is an ideal species for studies intended to introduce students to field biology - they are small, docile, easy to catch, have bright colors that are easy to quantify, are habituated to people, and nest in conspicuous locations on campus. In addition, House Finches are found in nearly every schoolyard in the U.S., and part of this study will also develop science exercises with high school teachers, and allow students to experience the challenge and excitement of real scientific investigation.