Genetic Diversity and Distribution Patterns of Host Insects of Caterpillar Fungus Ophiocordyceps sinensis in the Qinghai-Tibet Plateau

Abstract

The caterpillar fungus Ophiocordyceps sinensis is one of the most valuable medicinal fungi in the world, and it requires host insects in family Hepialidae (Lepidoptera) to complete its life cycle. However, the genetic diversity and phylogeographic structures of the host insects remain to be explored. We analyzed the genetic diversity and temporal and spatial distribution patterns of genetic variation of the host insects throughout the O. sinensis distribution. Abundant haplotype and nucleotide diversity mainly existed in the areas of Nyingchi, ShangriLa, and around the edge of the Qinghai-Tibet Plateau, where are considered as the diversity center or micro-refuges of the host insects of O. sinensis. However, there was little genetic variation among host insects from 72.1% of all populations, indicating that the host species composition might be relatively simple in large-scale O. sinensis populations. All host insects are monophyletic except for those from four O. sinensis populations around Qinghai Lake. Significant phylogeographic structure (NST>GST, P<0.05) was revealed for the monophyletic host insects, and the three major phylogenetic groups corresponded with specific geographical areas. The divergence of most host insects was estimated to have occurred at ca. 3.7 Ma, shortly before the rapid uplift of the QTP. The geographical distribution and star-like network of the haplotypes implied that most host insects were derived from the relicts of a once-widespread host that subsequently became fragmented. Neutrality tests, mismatch distribution analysis, and expansion time estimation confirmed that most host insects presented recent demographic expansions that began ca. 0.118 Ma in the late Pleistocene. Therefore, the genetic diversity and distribution of the present-day insects should be attributed to effects of the Qinghai-Tibet Plateau uplift and glacial advance/retreat cycles during the Quaternary ice age. These results provide valuable information to guide the protection and sustainable use of these host insects as well as O. sinensis.

Phylogeography and evolution of a fungal–insect association on theTibetanPlateau

“…The origination time estimate of the fungus based on the 5‐locus data set, however, differed from that based on the ITS data set, but was similar to the time estimate of host insects reported by Quan et al . (). Using a slower substitution rate, Quan et al .…”

“…Using a slower substitution rate, Quan et al . () revealed that host insects first diverged around 4.1 Mya. In the absence of fossil evidence and/or more robust molecular clocks for these two organisms, the above time estimates must be considered tentative.…”

The Mechanisms of Pharmacological Activities ofOphiocordyceps sinensisFungi

“…A substantial intraspecific genetic diversity has been observed in O . sinensis , which may be because of the diversity of terrains and climates on the Tibetan Plateau and the broad insect host range (more than 50 species in the family Hepialidae ) (Quan et al ., ; Zhang et al ., ). The genetic divergence of O .…”

“…O . sinensis is widely distributed on Tibetan Plateau and its surrounding regions (Liang et al ., ; Quan et al ., ; Zhang et al ., ). In China, it is commonly called ‘Dong Chong Xia Cao’ (means ‘winter worm summer grass’) and has been used as a medication in China for over 300 years (Wang, ).…”

Preliminary molecular phylogeny and biogeography of the monobasic subfamily Calinaginae (Lepidoptera, Nymphalidae)

“…Therefore, the genetic diversity and the present-day distributions of Calinaga should be attributed not only to the dramatic geological events in Oligocene/Miocene, but also to the impacts of the cycles of glacial advance/retreat that occurred in this region during the Pleistocene (Quan et al 2014).…”