The role of habitat heterogeneity on signal evolution in predator–prey interactions, with implications for the evolution of crypsis and aposematism

Little is known about mechanisms promoting the diversity of antipredation strategies found in nature. In this study I explore how habitat heterogeneity may have profound effects on predator–prey communication. Habitat heterogeneity inevitably increases background noise in communication systems. Therefore, as habitat heterogeneity increases, an organism must produce more signal in order to convey the same amount of information (signal–to–noise ratio; S/N). Therefore, all else equal, strategies maximizing S/N (e.g. aposematism, sexually–selected traits) should become more exacerbated as habitat heterogeneity increases, whereas strategies minimizing S/N (e.g. crypsis) should show the opposite trend. A test of this hypothesis is provided based on information on detection-avoidance strategies of Ghanaian preying mantids. If this hypothesis is widely applicable, it can provide a parsimonious explanation for the origin of aposematism, given that the same organisms can become more cryptic or aposematic simply by shifting their habitats and the corresponding levels of background noise.