Quality or quantity? the role of donor condition in the production of chemical alarm cues in juvenile convict cichlids

Abstract

AbstractMuch study has been devoted to the function of chemical alarm cues in predator-prey relationships in aquatic environments, but little is known about the production of these valuable sources of chemosensory information. Recent studies have demonstrated that donor (cue sender) condition may play an important role in the production of chemical alarm cues in juvenile convict cichlids (Archocentrus nigrofasciatus). In laboratory experiments, we conducted trials to test for the effect of donor body condition on the minimum behavioural response threshold and/or intensity of antipredator response to conspecific chemical alarm cues. Chemical alarm cue donors were sampled from high or low condition populations. Pairs of juvenile cichlids were exposed to the skin extracts of high condition versus low condition donors, across a range of relative concentrations (200, 100, 50, 25, and 12.5%), and a distilled water control. We found that cichlids exhibited overt antipredator behaviour beginning at a concentration of 25% for the high condition cue, while a minimum response threshold concentration of 50% was seen for low condition cue. The intensity of antipredator response was greater following exposure to the alarm cues of high condition stimulus versus low condition donors. Taken together, these findings suggest that the damage-released chemical alarm cues from high condition donors are qualitatively and quantitatively greater than those of low condition donors.