Phylogeographic structures of the host insects of Ophiocordyceps sinensis

A fungus-insect complex, known as DongChong XiaCao, is formed from the infection of the hepialid larvae by the fungus Ophiocordyceps sinensis, which is endemic to the Qinghai-Tibetan Plateau (QTP). Due to previously limited sample collection size, the data about the diversity and structure of the host insect was insufficient and lacked details. The purpose of this study was aimed to discuss the diversity and phylogeography of the host insects of O. sinensis with a large-scale sampling. The mitochondrial cytochrome oxidase I gene (cox1) was sequenced and analyzed among 710 samples representing 88 geographic locations. 205 haplotypes of cox1 were identified from all the 710 samples and 4 phylogenetic clades with 12 subclades were identified. Instead of the single latitude-based divergence suggested previously, three distribution patterns were deduced to correspond to the phylogeographic structures, including but not limited to the co-existence of a wide and specific local phylogeographic distribution structures. Two separate genetic diversity and differentiation centers, namely the northwestern Yunnan and the southeastern Tibet were identified. Dating analyses from three calibrations supported that the divergence of the 4 clades occurred in the Oligocene-Miocene period (30.54-13.66 million years ago) (Ma), which were connected with the second and third geological movements of the QTP (17-25, 8-13 Ma). Our results provide a more detailed understanding of the divergence and distribution patterns of the host insects of O. sinensis.