Data from: Multiple signaling in a variable environment: expression of song and color traits as a function of ambient sound and light

Many animals communicate using more than one signal, and several hypotheses exist to explain the evolution of multiple signals. However, these hypotheses typically assume static selection pressures and previous work has not addressed how spatial and temporal environmental variation can shape variation in signaling systems. In particular, environmental variability, such as ambient lighting or noise, may affect efficacy (e.g. detectability/perception by receivers) of signals. To examine how signal expression varies intraspecifically as a function of habitat characteristics, we evaluated relationships between spatial environmental variation and song and plumage color expression in a tropical songbird, the red-throated ant-tanager (Habia fuscicauda) in Panama. We recorded male ant-tanager song, plucked feathers to measure coloration, and recorded the acoustic and light environments from each male’s territory. In addition, we took several morphometric measurements from each male to assess the potential information content of song and plumage color. We found that males with redder and more saturated crowns occurred on darker territories, and males that sang shorter and lower frequency songs occurred on noisier territories. We also found that more colorful males tended to sing longer and lower frequency songs. Finally we found that song and color correlated similarly with male morphology (e.g. tarsus length, body mass). Altogether these results indicate that spatial variation in the environment is related to male coloration and song, and that males might be optimizing color and song expression for their particular territorial environment.

众多动物依托多重信号开展交流，学界已提出多项假说来阐释多信号通信的演化历程。然而此类假说通常默认选择压力处于静态，且既往研究尚未探讨时空环境变异如何塑造信号系统的变异。具体而言，环境变异（如环境光照或噪声）可能会影响信号的传递效能，例如接收者的可检测性与感知能力。
为探究信号表达在种内水平上如何随生境特征发生变化，我们以巴拿马的热带鸣禽——红喉蚁唐纳雀（Habia fuscicauda）为研究对象，分析了其空间环境变异与鸣唱、羽色表达之间的关联。我们录制了雄性红喉蚁唐纳雀的鸣唱声，拔取其羽毛以测定羽色，并记录了每只雄鸟领地内的声学与光照环境。此外，我们还对每只雄鸟开展了多项形态测量，以评估鸣唱与羽色所携带的潜在信息含量。
研究结果显示，冠羽更红、饱和度更高的雄鸟栖息于光照更弱的领地，而鸣唱时长更短、频率更低的雄鸟则分布于噪声更强的领地。此外我们还发现，羽色更艳丽的雄鸟往往会鸣唱时长更长、频率更低的鸣曲。最后，我们观察到鸣唱特征与羽色均与雄鸟形态指标（如跗跖长度、体质量）呈现相似的相关性。
综合来看，本研究结果表明，环境的空间变异与雄鸟的羽色和鸣唱特征存在关联，雄鸟或可针对自身所处的领地环境优化其羽色与鸣唱表达。