Phylogenetic and genetic evolutionary analyses of the mitochondrial genome of in from the Qinghai-Tibetan Plateau.

The larvae of the nematode family can infect several animals. is a parasitic nematode that infects mammals and has a worldwide distribution. In this study, the phylogenetic relationships and differentiation time of collected from were studied using molecular methods. The phylogenetic tree constructed based on 12 protein-coding genes (PCGs), cytochrome oxidase subunit I (), 18S rRNA, and 28S rRNA showed that was closely related to the Onchocercidae family and that this relationship was highly node-supported. The mitochondrial genome of was found to be a circular double-stranded DNA molecule with 32 mitochondrial genes, including 12 PCGs (ND4L, CYTB, ND1-6, , ATP6), 18 tRNA genes, and 2 rRNA genes (s-rRNA and L-rRNA). The divergence time based on mitochondrial generation suggests that was formed approximately 391 million years ago. Overall, this study can provide valuable data for the further study of the phylogeny and differentiation time of in the Qinghai-Tibetan Plateau.IMPORTANCEOur study demonstrates the close genetic relationship between and the Onchocercidae family. Although previous studies have demonstrated this phylogenetic relationship, it was confirmed in our study using the genetic markers , 18S rRNA, 28S rRNA, and the 12 protein-coding genes of parasitized on from the Qinghai-Tibetan Plateau (QTP). A relatively close relationship was also found between and the Tetrameridae family. We analyzed the divergence time of and speculated that in the QTP might have originated in the Mediterranean region and that there might have been a mutual transmission between in the Mediterranean, transmitting to the QTP.