The ecology and evolution of cues and signals in animal interspecies cooperation

Mutualistic interactions have played a central role in generating biodiversity and are often facilitated by an exchange of information between participating parties. Cues and signals are likely to be particularly crucial in animal interspecies cooperation, a specific form of mutualism that depends on real-time, interactive behavioural coordination to secure mutual benefit. Yet, despite the taxonomic breadth and ecological significance of these interactions, our understanding of the roles of cues and signals in animal interspecies cooperation remains relatively underexplored compared to their well-documented roles in other mutualisms, intraspecies cooperation and interactions involving collective behaviour. Here, we examine the ecology and evolution of cues and signals in animal interspecies cooperation. Drawing on diverse natural history examples, we first assess the ecological functions, benefits and costs of cues and signals, and discuss how the information they convey about partner identity, motivation and reliability informs decisions about whether, when and how to cooperate with heterospecifics. Second, we outline the evolutionary origins, variation and heritability of cues and signals, and discuss the potential for coevolution between signallers and perceivers. Third, we draw on relevant insights from broader mutualisms and cooperation within species to highlight key similarities and differences in the use of cues and signals across interaction types. Overall, our review clarifies how information underpins animal interspecies cooperation, highlights key gaps in the scientific literature, and identifies promising avenues for future research on its ecological and evolutionary significance.