Genetic Diversity Of MHC Genes And Mitochondrial Sequences In Captive Forest Musk Deer (Moschus Berezovskii) Genetic Diversity Of MHC Genes And Mitochondrial Sequences InCaptive Forest Musk Deer (Moschus Berezovskii)Cai Ruibo (Conservation And Utilization

The forest musk deer (Moschus berezovskii) is a high elevation species distributed across western China and northern Vietnam. Once abundant, habitat loss and poaching has led to a dramatic decrease in population numbers, prompting the IUCN to list the species as endangered.1) Here, we characterized the genetic diversity of a Major Histocompatibility Complex (MHC) locus and teased apart driving factors shaping its variation. Seven DRB exon 2 alleles were identified among a group of randomly sampled forest musk deer from a captive population in the Sichuan province of China. Compared to other endangered or captive ungulates, forest musk deer have relatively low levels of MHC genetic diversity.2) Non-synonymous substitutions primarily occurred in the putative peptide-binding region (PBR) with analyses suggesting that recombination and selection have shaped the genetic diversity across the locus. Specifically, inter-allelic recombination generated novel allelic combinations, with evidence for both positive selection acting on the PBR and negative selection on the non-PBR. An improved understanding of functional genetic variability of the MHC will facilitate better design and management of captive breeding programs for this endangered species.3) We analyzed the spatial genetic variation in both the mitochondrial DNA (mtDNA) control region and the major histocompatibility complex (MHC) DRB locus from the Western Sichuan and Qinling mountains in China to characterize the population structure and evolutionary history of musk deer.4) We observed moderate levels of divergence between the two regional captive populations that might be caused by the historic divergence of their ancestors, as the divergence time between lineages dated to approximately 37,800-56,700 years ago. The MHC data suggested that selection impacted the allele frequency of DRB in the two regions, possibly reflecting local adaptation to pathogen exposure. Importantly, DRB allelic and mitochondrial haplotype diversity observed in Qinling Mountains population were higher than in Western Sichuan, suggesting that forest musk deer from Western Sichuan are likely to have originated from the Qinling Mountains, which was partially supported by demographic modeling.5) Based on the genetic differentiation and spatial separation between the two regional subpopulations, we recommend treating these regions as distinct management units that should be managed with the goal of maintaining the species" evolutionary potential.