Organized Meeting
Yoko Matsumura
Assistant Professor/ Dr.
Hokkaido University
Sapporo, Japan
Together with Dermaptera, Zoraptera is likely the first split among the polyneopteran orders. To understand the evolution of Polyneoptera, accumulating more knowledge on zorapteran species is essential. Based on a broad taxon sampling from all continents where the group is known we conducted the first species-level phylogeny, using partial sequences of 18S rRNA, Histone 3, 16S rRNA, and 12S rRNA genes. The resulting phylogenetic trees show that Zoraptera is divided into three major clades, and that two of them are composed of species distributed on different continents. The monophyly of these clades is at least partly supported by shared derived morphological features. The divergence age estimation and ancestral distribution area reconstruction unveiled an ancient origin and early radiation initiated in the Permian. The plate tectonics theory suggests that the present distribution of Zoraptera was mainly established by vicariance, rather than dispersal. The three major clades likely originated on the Pangaea supercontinent, or alternatively on the Gondwana and Laurasia supercontinents. Their ancient origin explains previously found conspicuous interspecific divergence variation of the spermatozoa morphology, genital apparatus, sperm structure, and mating behavior, in striking contrast to a highly conserved general body morphology. We also compiled data on available reproductive features and reconstructed the character evolution. Although homologies in the genital character system are not fully established yet, the analyses revealed repeated acquisitions and/or losses of a hyper-elongated intromittent organ, mating hooks, and tergal protuberances. We will also discuss the impact of their miniaturization on the evolution of Zoraptera.