Knowledge about the impact of different geographical environments on rhesus macaque gut microbiota is limited. In this study, we compared the characteristics of gut microbiota in six different Chinese rhesus macaque populations, including Hainan, Nanning, Guizhou, Xichang, Jianchuan and Tibet. Through the composition analysis of operational taxonomic units (OTUs), we found that there were significant differences in the abundance of core overlapping OTUs in the six Chinese groups. Specifically, the Tibet population exhibited the highest gut microbial diversity and the most unique OTUs. Statistically significant differences in the composition of gut microbiota among the six groups at phylum and family level were evident. Specifically, Tibet had higher abundances of Firmicutes and lower abundances of Bacteroidetes than the other geographical groups, and the higher abundance of Firmicutes in the Tibetan group was mainly caused by a significant increase in the family Ruminococcaceae and Christensenellaceae. Phylogenetic investigation of communities by reconstruction of unobserved state analysis showed that the enrichment ratio for environmental information processing and organismal systems was the highest in the Tibet population. Additionally, our results suggested that in the adaptation process of rhesus macaques to different geographical environments, the abundance of the core common flora of the intestinal microbes had undergone varying degree of change and produced new and unique flora, both of which helped to reshape the gut microbiota of rhesus macaques. In particular, this change was more obvious for animals in the high-altitude environments.

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Bamboo-eating giant panda (Ailuropoda melanoleuca) is an enigmatic species, which possesses a carnivore-like short and simple gastrointestinal tract (GIT). Despite the remarkable studies on giant panda, its diet adaptability status continues to be a matter of debate. To resolve this puzzle, we investigated the functional potential of the giant panda gut microbiome using shotgun metagenomic sequencing of fecal samples. We also compared our data with similar data from other animal species representing herbivores, carnivores, and omnivores from current and earlier studies. We found that the giant panda hosts a bear-like gut microbiota distinct from those of herbivores indicated by the metabolic potential of the microbiome in the gut of giant pandas and other mammals. Furthermore, the relative abundance of genes involved in cellulose- and hemicellulose-digestion, and enrichment of enzymes associated with pathways of amino acid degradation and biosynthetic reactions in giant pandas echoed a carnivore-like microbiome. Most significantly, the enzyme assay of the giant panda's feces indicated the lowest cellulase and xylanase activity among major herbivores, shown by an in-vitro experimental assay of enzyme activity for cellulose and hemicellulose-degradation. All of our results consistently indicate that the giant panda is not specialized to digest cellulose and hemicellulose from its bamboo diet, making the giant panda a good mammalian model to study the unusual link between the gut microbiome and diet. The increased food intake of the giant pandas might be a strategy to compensate for the gut microbiome functions, highlighting a strong need of conservation of the native bamboo forest both in high- and low-altitude ranges to meet the great demand of bamboo diet of giant pandas.

The diet of a habituated group of black crested gibbon (Nomascus concolor jingdongensis) was studied from March 2005 to April 2006 in the Wuliang Mountains, central Yunnan, China. Gibbons consumed 77 different plant species, one mammal-, two bird-, one lizard-, and two insect-species. Buds and leaves constituted 46.5% of the diet (21.0% vine leaves and buds, 19.2% tree leaves and buds, and 6.3% epiphyte leaves). Fruits, figs and flowers accounted for 25.5, 18.6 and 9.1% of the diet, respectively. There was marked seasonal variation in dietary proportions. Fruit varied from 0.3 to 82.7%; figs from 0 to 68.2%; tree leaves and buds from 1.5 to 83.3%; vine leaves and buds from 3.1 to 61.9%; and epiphyte leaves from 0 to 22.2% of the diet. Different food types dominated the diet in different months during the study period. The foli-frugivorous diet and extreme seasonal variation in the diet may be related to the harsh habitat of the study group.