Better the devil you know? How familiarity and kinship affect prey responses to disturbance cues

Prey can greatly improve their odds of surviving predator encounters by eavesdropping on conspecific risk cues, but the reliability of these cues depends on both previous accuracy as well as the cue’s relevance. During a predator chase, aquatic prey release chemical disturbance cues that may vary in their reliability depending on the individuals receiving them. Thus, prey may rely differentially on disturbance cues from familiar individuals (due to previous experience) or from kin (due to their relatedness). We examined the responses of wood frog (Lithobates sylvaticus) tadpoles to disturbance cues from familiar versus unfamiliar conspecifics and kin versus non-kin. In accordance with our prediction, tadpoles responded differently to disturbance cues from familiar versus unfamiliar conspecifics. Tadpoles receiving disturbance cues from unfamiliar individuals displayed a fright response, whereas tadpoles ignored disturbance cues from familiar individuals. Tadpoles may have habituated to familiar cues since they were unaccompanied by a true threat, hence rendering these cues functionally unreliable. Tadpoles responded similarly to disturbance cues from related and unrelated individuals suggesting they were similarly reliable and this mirrors the matching reliability of prey responses to damage-released alarm cues from kin and non-kin. Our findings shed light on a seldom-studied chemical communication system in aquatic prey. Tadpoles trust the chemical cues of strangers over familiar individuals that may have been unreliable about predators in the past. Tadpoles release “disturbance cues” in response to predators that warn of danger to nearby tadpoles, causing them to reduce their movement. We exposed tadpoles to disturbance cues from familiar versus unfamiliar tadpoles, and siblings versus nonsiblings. Interestingly, tadpoles did not respond to cues from familiar tadpoles, but did to strangers, siblings, and non-siblings.