DISSERTATION RESEARCH: Aggressive Signaling and Fitness Consequences in a New World Warbler

争夺有限资源的动物之间经常发生纠纷。在这种情况下，动物可能会通过使用刻板的交流信号，如视觉或声音显示，来避免直接战斗。联合研究所之前对鸣禽黑喉蓝莺的声音信号进行的研究表明，在预测未来的攻击行为方面，两种声音显示特征是特别“诚实”的威胁信号。具体来说，非常安静的歌曲（“柔和的”歌曲）和特定的歌曲类别（“II型”歌曲）都可以可靠地预测鸟类是否会攻击模型对手。拟议研究的第一部分将测试这两种信号特征是否传达了不同程度的威胁，以及鸟类是否以及如何通过单独或依次调节这两种鸣叫特征来升级攻击性互动。为了达到这个目的，一项现场实验将模拟强度逐步升级的互动式歌曲比赛。在低水平升级时发出II型歌曲的鸟类预计在升级的较高阶段会发出柔和的歌曲，每一个更高的阶段都成为最终攻击的更可靠的预测器。这个实验将表明动物纠纷是否像最近的理论工作所预测的那样，遵循一个等级“阶梯”的升级。拟议研究的第二部分是询问动物是否以及如何通过使用威胁表现而受益。男性在威胁表现使用上的自然差异将被记录下来，声音互动的“赢家”和“输家”将根据谁先让步进行编码。遗传父权分析将提供威胁表现和繁殖成功之间的相关性。据预测，更频繁地使用威胁表现并在与对手的互动中“赢得”更多的雄性在繁衍后代方面更成功。该项目将为本科生提供实地研究经验，并将在小学生的外展活动中展示。

Disputes often arise among animals competing for limited resources. In such circumstances, animals may avoid direct combat through use of stereotyped communication signals, such as visual or vocal displays. Prior studies by the co-PI on vocal signaling in a songbird, the black-throated blue warbler, showed that two vocal display features are particularly "honest" signals of threat, in terms of forecasting future aggression. Specifically, the production of extremely quiet songs ("soft" songs) and a certain song category ("type II" songs) both reliably predict whether a bird will subsequently attack a model opponent. The first part of proposed research will test whether these two signal features convey differing levels of threat, and if and how birds may escalate aggressive interactions by modulating these two song features either alone or in sequence. Towards this end, a field experiment will simulate interactive song contests that escalate in intensity. Birds that respond with type II songs during low levels of escalation are predicted to give soft songs during higher stages of escalation, with each higher stage becoming a more reliable predictor of eventual attack. This experiment will indicate whether animal disputes follow a hierarchical "ladder" of escalation, as has been predicted in recent theoretical work. The second part of proposed research asks if and how animals benefit through their use of threat displays. Natural variation among males in threat display use will be documented, and "winners" and "losers" of vocal interactions coded based on who backs down first. Genetic paternity analysis will provide estimates of correlations between threat displays and reproductive success. Males that more frequently use threat displays and "win" more interactions against opponents are predicted to be more successful at siring offspring. This project will provide field research experience for undergraduates, and will be showcased in outreach activities to elementary school students.