On the origin of the New World Pyrgomorphidae (Insecta: Orthoptera)

摘要

The gaudy grasshopper family Pyrgomorphidae (Orthoptera: Caelifera) shows a peculiar geographical distribution. Of the 487 described species, less than 10% of the diversity is found in the New World, while the rest occur throughout Africa, Asia, and Australia. Only 41 species belonging to four tribes are found in Central and South America and Dominican Republic, and the phylogenetic positions of these taxa within the large phylogeny of Pyrgomorphidae and the relationships among them have never been investigated. Regarding the biogeography, three different hypotheses about the origin of the New World Pyrgomorphidae have been proposed, but these have not been empirically tested. In this study, we present the first molecular phylogeny of Pyrgomorphidae that includes the members of all four New World tribes and representative genera from the Old World based on entire mitochondrial genome and four nuclear genes to investigate the biogeography of this fascinating lineage. Our results recover Pyrgomorphidae as monophyletic and the New World Pyrgomorphidae as a paraphyletic group comprising three clades, consisting of: (1) The Caribbean Jaragua + the South American Algete; (2) The Mexican and Central American Sphenarium + Prosphena; and (3) The Mexican lineages Ichthiacridini + Ichthyotettigini. The divergence time estimation analysis suggested that the Pyrgomorphidae diverged from its relatives in the Early Cretaceous (139-104 mya). The biogeographic analysis using BioGeoBEARS showed that after diversifying in the Old World, the first New World Pyrgomorphidae clade (Algete + Jaragua) diverged 96 mya (Late Cretaceous, Cenomanian) and that their current distribution in the New World is explained by two possible events, a transatlantic colonization from Africa to Northern South America or a vicariance event between these two landmasses, followed by a subsequent dispersal to the Caribbean. The second wave of colonization occurred about 69 mya towards the end of the Late Cretac