Collaborative Research: Causes of Variation in Parid Call Complexity

人类语言是已知的最复杂的交流系统。然而，许多非人类动物物种也有相当复杂的交流系统，包括非人类灵长类动物、鲸鱼和海豚，甚至许多鸟类物种。然而，对于人类语言和非人类交流系统来说，推动这种复杂性的关键因素在很大程度上仍然是未知的。发现这些因素对于理解这种复杂行为的起源和进化至关重要，包括我们自己祖先的语言起源。这项拟议的研究将使用观察和实验方法来测试提出的解释声音交流复杂性的三个关键因素：社会复杂性和群体规模，捕食风险，以及栖息地对声音传播的限制。研究人员将在两种常见的北美鸟类身上研究这些因素，这两种鸟类拥有复杂的发声行为系统和复杂的社会结构：卡罗莱纳山雀和丛生山雀。研究人员将把他们的成果纳入他们的教学，并指导多名学生研究人员使用当前的研究方法，包括大数据管理战略，以及通过与伊利诺伊大学超级计算设施相关的极端科学和工程发现环境计划与超级计算工作人员合作。卢卡斯和弗里伯格将继续为《美国科学家》等大众期刊撰写关于这项工作的文章，他们在2012年共同撰写了一篇文章，在美国和海外有成千上万的读者阅读。是什么因素推动了复杂信号的进化？社会复杂性假说认为，形成复杂社会群体的物种或种群比形成更简单群体的物种或种群需要更复杂的信号系统。尽管有越来越多的证据支持社会复杂性假说，但一个关键的局限性是，它很少与其他假说进行对比测试。这项拟议的工作使用了Paridae科两种鸟类(Carolina chickadees，Poecile carolinens和丛生山雀Baeolophus biolor)的叫声来测试社会复杂性假说和解释沟通复杂性的两个主要替代假说：(1)社会复杂性：较复杂群体中的个体比较简单群体中的个体产生更复杂的叫声。(2)栖息地限制：较开放栖息地的个体比较封闭栖息地的个体产生更复杂的叫声。(3)捕食压力：在捕食者密度或多样性较高的生境中，个体发出的叫声比面对较少捕食者的个体发出的叫声更复杂。这些假说将通过田纳西大学和佛罗里达大学的圈养羊群实验、收集的未经操纵的野生羊群数据、野外回放实验以及田纳西大学和普渡大学预定的部分森林砍伐前后的羊群观察，以前所未有的分辨率检验。这项工作将增加对复杂交际行为的功能和机制的理解，并提供关于个人层面的复杂行为如何从个人所处的社会和物理环境的性质中出现的基本信息。Parid物种现在通常被用作研究社会信息使用及其在动物群中的适合性后果的模式系统。这项工作为理解Parid Call复杂性的性质奠定了坚实的基础，进而生成了许多物种在快速变化的世界中用于与健康相关的决策的微调信息。调查人员打算将数据存放在田纳西大学机构储存库TRACE(http://trace.tennessee.edu/)，)中，田纳西大学图书馆的工作人员将在那里为长期保存和管理提供评估。TRACE解决了存放研究的访问、安全、保存和版权问题，并确保全球研究人员可以找到数据，分配数字对象标识符(DOI)鼓励适当引用和重复使用。

Human language is the most complex communication system known. However, many non-human animal species also have quite complex communication systems, including non-human primates, whales and dolphins, and even many bird species. The key factors driving such complexity, though, remain largely unknown for both human language and for non-human communication systems. Discovering these factors is crucial to understanding the origin and evolution of such complex behavior, including the origin of language in our own ancestors. The proposed research will use observational and experimental methods to test three key factors proposed to explain vocal communication complexity: social complexity and group size, predation risk, and habitat-induced constraints on sound transmission. The investigators will examine these factors in two common North American bird species that possess complex systems of vocal behavior as well as complex social structures: Carolina chickadees and tufted titmice. The researchers will include their results in their teaching and mentor multiple student researchers in current research methods including Big Data management strategies, and collaborting with supercomputing staff through the Extreme Science and Engineering Discovery Environment program associated with the University of Illinois supercomputing facility. Lucas and Freeberg will continue to write about this work for general-audience journals like American Scientist, where they co-authored a 2012 article that has been read by thousands of readers in the U.S. and abroad.What factors drive the evolution of complex signals? The Social Complexity Hypothesis posits that species or populations forming complex social groups require more complex signaling systems than species or populations that form simpler groups. Although there is increasing evidence to support the Social Complexity Hypothesis, a key limitation is that it is rarely tested against alternative hypotheses. The proposed work tests the Social Complexity Hypothesis against two major alternative hypotheses to explain communicative complexity, using chick-a-dee calls of two avian species of the family Paridae (Carolina chickadees, Poecile carolinensis, and tufted titmice, Baeolophus bicolor): (1) Social Complexity: Individuals in more complex flocks produce calls with greater complexity than individuals in simpler flocks. (2) Habitat Constraints: Individuals in habitats that are more open produce calls with greater complexity than individuals in more closed habitats. (3) Predation Pressure: Individuals in habitats with a greater density or diversity of predators produce calls with greater complexity than individuals facing fewer predators. The hypotheses will be tested with unprecedented resolution through captive flock experiments at the University of Tennessee and University of Florida, data collected on un-manipulated wild flocks, field playback experiments, and observations of flocks before and after scheduled partial forest cuts at the University of Tennessee and Purdue University. The work will increase understanding of the function and mechanisms of complex communicative behavior and provide fundamental information about how complex behavior at the level of the individual emerges from the nature of the social and physical environmental setting in which the individual lives. Parid species are now commonly utilized as a model system for the study of social information use and its fitness consequences in animal communities. This work lays a solid foundation for understanding the nature of parid call complexity and, in turn, the generation of finely tuned information used by many species in fitness-related decision-making in a rapidly changing world. The investigators intend to deposit the data in the University of Tennessee institutional repository, Trace (http://trace.tennessee.edu/), where University of Tennessee Libraries staff will provide appraisal for long-term preservation and stewardship. Trace addresses access, security, preservation, and copyright of deposited research, and ensures that global researchers can find the data, with the assignment of Digital Object Identifiers (DOIs) encouraging proper citation and re-use.