Group-living prey rely on social information such as alarm signals and other social cues to avoid predation. By definition, “signals” imply that a message is voluntarily directed at receivers (i.e., the audience), whereas “cues” are released incidentally regardless of the audience composition. Thus, audience effects can be used to differentiate between signals and cues when communication is difficult to observe or quantify. In at least two fish species, chemical disturbance cues are released during a predator attack to signal to familiar audiences about predation risk. Here, we examined whether audience composition affects disturbance cue release in wood frog (Lithobates sylvaticus) tadpoles to better understand the function of disturbance cues across aquatic prey. Groups of tadpoles underwent simulated predator attacks to obtain disturbance cues. The groups were either familiar and related, unfamiliar and related, familiar and unrelated, or unfamiliar and unrelated. To assess the relative potency of each cue, we used a behavioral bioassay design involving activity changes in independent tadpole receivers (unfamiliar and unrelated to the donors). If tadpoles use disturbance cues to signal related and/or familiar individuals, we predicted increased fright responses in receivers to cues obtained from those groups. However, we detected no effect of audience composition, indicating that tadpoles release similar disturbance cues regardless of audience kinship or familiarity. Nevertheless, disturbance cues evoked a consistent antipredator response in receivers indicating that these chemicals still act as reliable risk cues. Further comparative studies using audience effects are necessary to understand how disturbance cues have evolved across aquatic prey. When aquatic prey encounter predators and are frightened, they release chemicals known as “disturbance cues” into the water. These chemicals alert other prey nearby of potential danger. For example, wood frog tadpoles release disturbance cues when they are being chased by a predator. Tadpoles that smell the disturbance cues of other tadpoles are less likely to be eaten by predators. Since wood frog tadpoles are often found in shallow ponds filled with both familiar siblings as well as other tadpoles that are unfamiliar and unrelated, we wondered if tadpoles would produce more disturbance cues when familiar or related tadpoles were nearby. Here, we show that no matter who the audience members are, familiar siblings or not, tadpoles release disturbance cues that cause similar fright. This suggests that disturbance cues are not released differently depending on the audience in this species.

中文翻译：

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忘记观众：蝌蚪会释放类似的干扰线索，无论血缘关系或熟悉程度如何

群体生活的猎物依靠社会信息，如警报信号和其他社会线索来避免捕食。根据定义，“信号”意味着消息是自愿指向接收者（即观众），而“提示”是偶然释放的，而不管观众的构成如何。因此，当交流难以观察或量化时，观众效应可用于区分信号和线索。在至少两种鱼类中，在捕食者攻击期间会释放化学干扰线索，向熟悉的观众发出关于捕食风险的信号。在这里，我们检查了观众组成是否会影响林蛙（Lithobates sylvaticus）蝌蚪的干扰提示释放，以更好地了解干扰提示对水生猎物的作用。成群的蝌蚪经历了模拟的捕食者攻击，以获得干扰线索。这些群体或者是熟悉的和相关的，陌生的和相关的，熟悉的和不相关的，或者是陌生的和不相关的。为了评估每个线索的相对效力，我们使用了行为生物测定设计，涉及独立蝌蚪接收器（不熟悉且与供体无关）的活动变化。如果蝌蚪使用干扰线索向相关和/或熟悉的个体发出信号，我们预测接收者对从这些群体获得的线索的恐惧反应会增加。然而，我们没有检测到观众构成的影响，这表明无论观众的血缘关系或熟悉程度如何，蝌蚪都会释放类似的干扰线索。然而，干扰线索在接收者中引起了一致的反捕食者反应，表明这些化学物质仍然是可靠的风险线索。需要使用受众效应进行进一步的比较研究，以了解干扰线索如何在水生猎物中进化。当水生猎物遇到捕食者并受到惊吓时，它们会将被称为“干扰信号”的化学物质释放到水中。这些化学物质警告附近的其他猎物潜在危险。例如，木蛙蝌蚪在被捕食者追逐时会释放干扰信号。能闻到其他蝌蚪扰乱线索的蝌蚪不太可能被捕食者吃掉。由于林蛙蝌蚪经常出现在充满熟悉的兄弟姐妹和其他不熟悉和不相关的蝌蚪的浅水池中，我们想知道当熟悉或相关的蝌蚪在附近时，蝌蚪是否会产生更多的干扰线索。在这里，我们表明无论观众是谁，无论是否熟悉的兄弟姐妹，蝌蚪都会释放引起类似恐惧的干扰线索。这表明干扰线索的释放不会因该物种的受众而异。