Fig. 1.

Study design and the dynamics of gut microbiota with altitude and residence time. A The collection of samples and the application of analytical methods. B The study cohort design and groups. C and D PCoA using the Bray–Curtis distance calculated based on the relative abundance of species. The 95% confidence ellipses are shown by circles. E The Bray–Curtis distance between the microbiota of the Han populations and Tibetan4k_NP. Wilcoxon rank sum test was used to evaluate the statistical significance of Bray–Curtis distance to Tibetan4k_NP between Han4k_6m and other groups. “ +  +  + ” above Han4k_6m indicates a significantly smaller Bray–Curtis distance for Han4k_6m compared to the other three groups, with all q values being less than 0.001. F The dendrogram for hierarchical clustering is constructed based on the Bray–Curtis distance between groups. G The relative abundance of top 10 genera in each group