Genus phylogenetic tree. To investigate the systematic phylogenetic relationship of species at the genus level, the combination of genus relative abundance and relations among the top 100 genera is represented. The inside components of the phylogenetic tree were built with the representative sequences of the genera, and the colour of the branches represent the corresponding phyla. The outside cycle indicates the relative abundance of genera under each group, and the colour of the abundance is represented by the different groups. Z3, adult; Z2,  sub-adults; Z1,  infant.