The snub-nosed monkey genus Rhinopithecus (Colobinae) comprises five closely related species (R. bieti, R. roxellana, R. brelichia, R. avunculus and R. strykeri). All these species are among the world’s rarest and most endangered primates. In addition to conservation value, Rhinopithecus species are unique in the context of adaptive evolution. They show a distribution across altitudinal gradients from 800m to 4,500m. Three (R. bieti, R. roxellana, and R. strykeri) evolved high altitude (>3000m), while the other two (R. brelichia and R. avunculus) inhabit lowland regions. The most notable among them is R. bieti, which is found exclusively on Tibetan Plateau in a narrow area between Yangtze and Mekong rivers, and has been thought as the highest altitude-dwelling nonhuman primate at elevations of 3,500-4,500m.
Recently, a study conducted by researchers from Yunnan University, Kunming Institute of Zoology, University of Chicago, Beijing Institute of Genomics, and et al. revealed the molecular mechanism of high-altitude adaptation of Rhinopithecus based on the genomic study. They report de novo whole-genome sequence of R. bieti and genomic sequences of other snub-nosed monkeys. Comparative genomic analyses find 8 common substitutions in 6 genes of three high-altitude snub-nosed monkeys, which are related to lung function, DNA repair, and angiogenesis, reflecting molecular adaptations of their high-altitude living. UV irradiation assay of CDT1 showed CDT1A537V is more resistant to UV irradiation. In vitro angiogenesis assay of RNASE4 showed RNASE4N89K+T128I has enhanced ability of inducing endothelial tube formation. Comparative transcriptomic analysis find highly expressed genes involved in cardiac muscle contraction and oxidative phosphorylation pathways were significantly enriched in energy consuming tissues of R. bieti. Genomic scans in one R. bieti and three R. roxellana populations identified overlapped genes between populations and population-specific genes involved in DNA repair, heart and vascular development, hypoxia response, energy metabolism, and angiogenesis. These results offer valuable insights into the non-human primate adaptive mechanism to high-altitude in the snub-nosed monkeys from different high-altitude regions for the first time.
This study is published on “Nature Genetics” (Genomic analysis of snub-nosed monkeys (Rhinopithecus) identifies genes and processes related to high-altitude adaptation, Nature Genetics, DOI: 10.1038/ng.3615).
(By Yu Li)
