Cooperation, Conflict and the Evolution of Social Signals

引人注目的装饰性特征，如五颜六色的鸟类羽毛，通常被视为性选择的同义词。美洲白骨顶的奇异雏鸟，有着鲜艳的橙色羽毛，羽毛经过修饰，头顶上覆盖着五颜六色的裸露皮肤，这让我们在更广泛的进化背景下思考装饰信号。先前的研究表明，亲代选择（父母对后代特定特征的偏爱）为美洲白骨顶的装饰后代提供了极强的自然选择，并提出了一个基本问题：为什么父母更喜欢装饰的后代？拟议的研究将通过调查小鸡信号的功能（即它们对父母行为的影响）以及这些影响对父母繁殖成功的后果（即所产生的后代的数量和质量）来回答这个问题。合作和冲突都可以影响社会信号系统的进化——确定每一种信号系统的相对重要性仍然是进化生物学家面临的一个重要挑战，也是本研究的主要焦点。实验操作小鸡信号（如羽毛颜色、喙颜色和皮肤颜色）将用于确定小鸡信号功能的机制及其对父母和后代的影响。研究人员将进行一项双因素实验，以研究雏鸟信号与父母食物分配策略（孵化不同步程度，后代竞争不对称的主要决定因素）之间的相互作用。该研究将通过探索自然选择如何塑造信号发送者和接收者，以及这些适应性结果如何相互作用以产生一个完整的社会系统，从而全面了解社会信号系统的进化。在实现这些研究目标的同时，本项目还将为本科生提供密集的指导。九名学生将参与研究计划的各个方面——从规划实地季节，到建立实地实验，到进行行为观察和数据管理与分析——并将获得科学调查的实践经验。

Striking ornamental traits such as colorful bird plumage are often viewed as synonymous with sexual selection. The bizarre chicks of the American coot, resplendent with their bright orange plumage of modified feathers and a head capped with colorful naked skin, challenge us to consider ornamental signals in a broader evolutionary context. Previous research revealed that parental choice (parental favoritism for particular offspring characteristics) provides extremely strong natural selection for ornamented offspring in American coots and raised a fundamental question: why do parents prefer ornamented offspring? The proposed research will answer this question by investigating how the chick signals function (i.e., their effects on parental behavior), and the consequences of these effects on the reproductive success of the parents (i.e., the number and quality of offspring produced). Both cooperation and conflict can shape the evolution of social signaling systems - determining the relative importance of each remains an important challenge for evolutionary biologists and is a major focus of the proposed research. Experimental manipulation of chick signals (e.g. plumage color, bill color, and skin color) will be used to determine both the mechanism of chick signal function and the consequences to parents and offspring. A two-factor experiment will be conducted to investigate the interaction between chick signals and parental tactics central to food allocation (degree of hatching asynchrony, the main determinant of offspring competitive asymmetries). The research will provide a comprehensive understanding of the evolution of a social signaling system by exploring how natural selection shapes both the signaler and the receiver, and how these fitness consequences interact to produce an integrated social system. While pursuing these research objectives, this project will also provide intensive mentoring of undergraduate students. Nine students will be involved in all aspects of the research program - from planning the field season, to setting up field experiments, to making behavioral observation and data management and analysis - and will gain hands-on experience with a scientific investigation.