Non-ecological radiations in acoustically communicating grasshoppers?

Abstract

The analysis of mechanisms of how populations differentiate and new species arise is fundamental for understanding the evolution of biological diversity. Mating preferences and sexually selected characters can rapidly diverge between populations, and this can probably lead to premating reproductive isolation and hence the evolution of new species. We have investigated the role of a complex bidirectional acoustic communication system for the radiation of grasshoppers of the subfamily Gomphocerinae. Species are characterized by species-specific songs, which result from complex stridulatory movement patterns of both hind legs. A molecular phylogeny indicates that within the genera Chorthippus and Stenobothrus several species-rich taxa diverged recently and thus represent independent radiations. Divergence in allopatry and hybridization after secondary contact are two mechanisms that led to new song types and female preferences and thus may have contributed to rapid speciation by the evolution of premating reproductive isolation.