Does donor group size matter? The response of guppies (Poecilia reticulata) and convict cichlids (Amatitlania nigrofasciata) to disturbance cues from conspecific and heterospecific donors

Prey are under immense pressure to make context-specific, behavioural decisions. Prey use public information to reduce the costs associated with making inappropriate decisions. Chemical cues are commonly used by aquatic vertebrates to assess local threats and facilitate behavioural decision making. Previous studies on chemosensory assessment of risk have largely focused on damage-released alarm cues, with the cues released by disturbed or stressed prey (i.e., disturbance cues) receiving less attention. Disturbance cues are "early-warning signals" common among aquatic vertebrates that may warn conspecific and heterospecific prey guild members of potential risk. Initially, we conducted a series of laboratory studies to determine (i) if guppies (Poecilia reticulata Peters, 1859) produce and respond to disturbance cues and (ii) if relative concentration (donor group size) determines response intensity. Secondly, we examined if guppies and convict cichlids (Amatitlania nigrofasciata (Gunther, 1867)) show similar response patterns to their own vs. heterospecific disturbance cues. Our results suggest that guppies exhibit increased predator avoidance behaviour to conspecific disturbance cues (relative to water from undisturbed conspecifics) and increased donor group size lead to stronger antipredator responses. However, although guppies and cichlids respond to each other's disturbance cues, we found no effect of donor group size towards heterospecific disturbance cues. Our results suggest that disturbance cues are not generalized cues and present a degree of species-specificity.