Speciation in gomphocerine grasshoppers: molecular phylogeny versus bioacoustics and courtship behavior

Varvara Vedenina (1), Nikolay Mugue (2)

1)Institute for Information Transmission Problems, Russian Academy of Sciences, B. Karetnyi per. 19, Moscow 127994, Russia E-mail: vedenin@iitp.ru
2) Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Vavilov str. 26, Moscow 119034 Russia E-mail: mugue@mail.ru

To understand the driving forces of speciation in grasshoppers of the subfamily Gomphocerinae, we compared the molecular phylogenetic tree with the distribution of the song pattern complexity and courtship behavior. In 51 grasshopper species of Gomphocerinae, a barcoding region of mitochondrial gene COI was sequenced and analyzed. A plesiomorphic pattern of calling song was shown to be predominant in the species of the most basal cluster including the tribes Chrysochraontini, Dociostaurini and Arcypterini. In the tribes Stenobothrini and Gomphocerini, plesiomorphic pattern of the calling song was found in less than half of the species studied; others demonstrated the increasing song complexity. The species of the basal cluster of the phylogenetic tree did not show complex courtship songs. Courtship songs that are different and more complex than the calling songs were only found in about half of species belonging to the tribes Stenobothrini and Gomphocerini. Most species with complex courtship (species of Stenobothrus genus, of Chorthippus albomarginatus group) were shown to be recently diverged species. Comparison of visual display accompanying complex courtship song revealed similarities between the species from different groups. According to the molecular phylogeny, complex courtship behavior in Gomphocerinae evolved independently and convergently. Since the courtship song can be used by a female to judge the mate quality, sexual selection is suggested to be the main driving force of rapid speciation in these young species.