Genetic Evidence Disapproves Coevolution between O.sinensis and Host Insects from Qing-Tibetan Plateau

Abstract Host-parasite coevolution is driven by the selective pressures each partner conferring on the other to merely maintain parity with other evolving species. Ophiocordyceps sinensis represents one of excellent model host-parasite complex, allowing us to explore evolutionary relationship between host and parasite. Although previous studies have demonstrated coevolution between O.sinensis and host insects, the incongruence in phylogenetic relationship of both is incompatible. In this study, we used ITS gene of O.sinensis and COI gene of host insects to evaluate the phylogenetic relationship, estimate the divergence time, infer demographic history, analyze identity by state distance matrix, and simultaneously explore evolutionary relationship or address the evolutionary pattern. We found distinct phylogenetic topology between O.sinensis and host insects from the main distribution of China. Additionally, the branch length ratio, demographic inference, and IBS analysis consistently suggested independent evolution between O.sinensis and host insects rather than arms race coevolution. However, populations of both O. sinensis and host insects from Qinghai lake showed similar evolution rate and phylogenetic topology, which might be associated with the formation of Qinghai Lake. Together, the data presented here provided new insights into host-parasite evolutionary relationship.