Technicolour deceit: a sensory basis for the study of colour-based lures

The study of deceptive signalling has provided compelling insights into evolutionary and ecological processes. Aside from mimicry, however, research into the use of colour as a deceptive instrument has progressed largely without an explicit theoretical basis. This is especially true for colour-based prey lures, that is, displays of colour used by predators to actively attract and deceive prey. Such lures are widespread and phenotypically diverse, and a valuable body of research has laid the foundation for novel tests of evolutionary theory in these systems. In this review, we aim to cast the study of colour-based luring under a theoretical framework centred on sensory drive, and outline hypotheses and predictions that may guide future work. We first discuss the principles of sensory drive theory, and briefly review its relevance and use in colour lure research. Notably, although rarely framed in explicit sensory drive terms, many studies consider questions highly relevant to this theory, such as the influence of signalling environments on lure evolution. We then highlight how hypotheses drawn from sensory drive theory may guide the study of intriguing features of colour lure systems. To that end, we review the empirical literature with a focus on two key areas: signal function and the evolution and maintenance of polymorphism. We examine the predictions of the relevant model of signal function, sensory traps, against the limited literature evidence in orb-web spiders, and find little support, at present, for the common contention that lures act as sensory traps via floral mimicry. Finally, we suggest that just as a more explicit consideration of sensory drive theory may allow new or broader insights into colour lure evolution, the study of lure systems offers unique opportunities to test theory in visual ecology, predator-prey dynamics and the evolution of polymorphism.