Adaptability Evolution Of Rhinopithecus Roxellana In Qinling River Based On MHC - DRB Gene

Golden snub-nosed monkey (Rhinopithecus roxellana) is a rare and endangered species endemic to China. They distributes in Sichuan/Gansu, Shanxi Qinling and Hubei Shennongjia. There are about 39 groups in Qinling Mountains. In 1960s, due to human activities, this species suffering from habitat loss and fragmentation that will cause their genetic diversity loss, so that they will be more sensitive to the disasters and environmental changes. Thus, it is important to study the evolutionary history and genetic diversity to create effective protection strategies for them. In this study, we chose 105 noninvasive samples from 4 groups in Qinling Mountains, combined High-throughput sequencing with genotyping by PCR-SSCP method. Twenty-nine alleles are segregated, and thirteen of whom are newly identified. That shows a high genetic diversity of golden snub-nosed monkeys’ DRB gene in the Qinling Mountains. We combined whole-genome sequencing results, the DRB alleles are distributed to two locus (DRB1, DRB2). In analysis of evolution, we found none of the alleles clustered with the pseudogenes which downloaded from NCBI during the phylogenetic analysis. This revealed that none of these alleles were pseudogenes. In addition, The alleles were not grouped by species, but were gathered with the other species, it is an major evidence for balancing selection. Balancing selection was revealed at DRB genes by excess non-synonymous substitutions at antigen binding sites (dN/ds>1), and by maximum-likelihood-based randomsite models, multiple sites were detected strong selection from M2a and M8 models. Both evidence show that the balance selection was an important mechanism to maintain the MHC genetic diversity of golden snub-nosed monkeys in Qinling Mountains. In this study, we find that the golden snub-nosed monkey’s MHC-DRB gene has high genetic diversity and the balance selection was an important mechanism to maintain the MHC genetic diversity. MHC gene closely contact with immune functions in vertebrate. Thus, it is important to study the evolutionary history and genetic diversity to create protection strategies for golden snub-nosed monkey and the other endangered species.