Evolutionary influences of sexual signalling on protective colouring

Sexual signals can reduce survival, constraining their evolutionary elaboration. However, it is unclear whether these signals, once evolved, similarly impact the evolution of naturally selected adaptations. We argue that this dynamic could be important for protective colouration, an extensively studied suite of adaptations that can also be under sexual selection. Sexual signals sometimes coevolve positively with conspicuous warning colouration, promoting synergistic, dual-function associations. However, when coupled through shared structures or behaviours, sexual traits might constrain the evolution of concealment strategies, resulting in suboptimal camouflage. We suggest hypotheses, approaches, and study systems to distinguish these opposing causal roles of sexual selection in shaping naturally selected adaptations such as protective colouration.