Interpopulation variation in sexual dichromatism in the neotropical grasshopper Sphenarium purpurascens (Orthoptera: pyrgomorphidae).

Cryptic coloration is an adaptative defensive mechanism against predators. Color patterns can become cryptic through background coloration-matching and disruptive coloration. Disruptive coloration may evolve in visually heterogeneous microhabitats, whereas background matching could be favored in chromatically homogeneous microhabitats. In this work, we used digital photography to explore the potential use of disruptive coloration and background matching in males and females of the neotropical grasshopper Sphenarium purpurascens in different habitats. We found chromatic differences in the three habitats and sexual dichromatism that may be explained by local adaptation. Even though females and males are sexually dichromatic, there are interpopulation differences in the magnitude of the sexual dichromatism. In an environment highly contrasting, but visually homogeneous, both males and females seem to follow mainly a disruptive strategy, whereas in highly contrasting and heterogeneous environments males and females seem to follow different color cryptic strategies, males are more disruptive than females. In contrast, females have a high background matching with less disruptive elements. The predators’ selective pressures in different microhabitats and the differences in mobility between sexes may explain the color pattern divergence between females and males.