Collaborative Research: Testing Alternative Hypotheses for the Maintenance of Behavioral Differences among Populations

这个项目将是现场和实验室联合研究的延续，旨在确定棕头牛鹂保持声乐方言的因素。这项研究将由加州大学圣巴巴拉分校的Stephen I. Rothstein博士和夏威夷大学的Robert C. Fleischer博士合作进行。他们的研究将包括：(1)深入研究一种大方言的发音变化，以确定不同地理尺度的变化对交流是否重要；(2)调查除目前强调的发音外的其他发音，以确定所有发音是否以相同的方式变化；(3)广泛的带状，形态学和生化研究。确定方言是否在基因上有差异，以及鸟类从一种方言向另一种方言分散的程度。这样的研究很重要，因为方言在鸣禽中很普遍，但却很少被理解。一种关于方言维持的假说认为，声音的差异促进了种群间的生殖隔离。这一假说认为方言具有重要的进化意义，甚至暗示它们可能影响物种形成的速度。由于鸟类研究在新物种起源的现代理论形成中发挥了重要作用，方言研究可能有助于我们理解进化生物学的这一关键方面。方言也很重要，因为它们的发音差异是后天习得的，因此代表了文化差异。这些鸟类的文化差异可能是动物中人类文化差异特征的最佳类比。信息，博士。罗斯坦和弗莱舍目前收集到的关于牛鹂的资料并不支持繁殖隔离假说。相反，雄性似乎分散开来，学习新的方言，但在学习新的方言之前，它们在一开始就处于劣势。这个过程与人类的行为是相似的，因为人们从一个国家或一种职业迁移到另一个国家，在他们学会新国家的语言或新职业的行话和技术术语之前，他们也处于不利地位。最后，这个项目也很重要，因为牛鹂是一种寄生物种，对几种濒危鸟类构成威胁。从该项目中获得的基本知识可用于提高目前由联邦政府和州政府在密歇根州和加利福尼亚州部分地区实施的强化牛郎鸟控制计划的有效性。

This project will be a continuation of combined field and laboratory studies designed to determine the factors responsible for the maintenance of vocal dialects in the brown-headed cowbird. The research will be carried out collaboratively by Dr. Stephen I. Rothstein of the University of California, Santa Barbara, and Dr. Robert C. Fleischer of the University of Hawaii. Their research will include (1) an intensive study of vocal variation within one large dialect, to determine if variation at different geographic scales is important to communication, (2) investigations of additional vocalizations besides the one emphasized so far, to determine if all vocalizations vary in the same manner, and (3) extensive banding, morphological, and biochemical studies, to determine if dialects are differentiated genetically and the degree to which birds disperse from one dialect to another. Such studies are important because dialects are prevalent among songbirds, yet are poorly understood. One hypothesis for the maintenance of dialects asserts that vocal differences facilitate reproductive isolation among populations. This hypothesis attributes major evolutionary significance to dialects and even suggests that they may influence rates of speciation. Because avian studies have played a major role in the formulation of modern theory about the origin of new species, dialect studies may contribute to our understanding of this critical aspect of evolutionary biology. Dialects are also important because the vocal differences that characterize them are learned and, therefore, represent cultural differences. These avian cultural differences may be the best analogs among animals of the cultural differences that characterize human populations. Information that Drs. Rothstein and Fleischer have gathered so far on the cowbird does not support the reproductive-isolation hypothesis. Instead, males seem to disperse and learn new dialects, but are at an initial disadvantage until they learn their new dialect. This process parallels human behavior in that people moving from one country or one profession to another are also at a disadvantage until they learn the language of their new country or the jargon and technical terms of their new profession. Lastly, this project is also important because the cowbird is a parasitic species that is a threat to several endangered bird species. Basic knowledge derived from the project may be used to increase the effectiveness of intensive cowbird-control programs currently being conducted by Federal and State governments in parts of Michigan and California.