Fig. 3

Sample overall classification-level tree diagram based on GraPhlAn Note: The classification level tree shows the hierarchical relationship of all classification units (represented by nodes) from the taxon to the genus (from the inner circle to the outer circle) in the sample population. The node size corresponds to the average relative abundance of the classification unit. The top 20 units of relative abundance are also identified by letters in the figure (from taxon to genus in order from outer layer to inner layer), and the shading colour on the letter is the same as the corresponding node colour