Beyond protection from predators: Correlates and additional benefits of aposematic signaling

Animals with defenses—whether physiological, morphological, or behavioral—that make them unprofitable to predators are often conspicuously colored. Such conspicuousness facilitates predator learning of the association between color and unprofitability. According to theory, this association, known as aposematism, enables predators to avoid defended prey in subsequent encounters through the stimulation of two or more sensory channels. Beyond their defensive function, warning coloration and secondary defenses have rarely been studied outside the context of predation, except for research on their role in sexual selection. This is surprising given the multiple additional benefits that well-defended animals can obtain. In this review, we draw mainly on examples from aposematic amphibians and insects to examine the behavioral and ecological correlates of aposematism, as well as the broader benefits it provides. We discuss how aposematism can shape behavior, ecology, and physiology, and influence diversification and extinction patterns. We also highlight the importance of considering both the primary (visual) and secondary (e.g., chemical, morphological, acoustic) components of warning displays, and how the aposematic phenotype may facilitate the evolution of complex and diverse behaviors in defended species. Finally, we assess the possible threats aposematic species face under global change and outline promising avenues for research to further clarify the wide-ranging benefits of aposematism across taxa.

University of Quindio
St. John's University
University College Dublin