Fig. 4.

Phylogenetic distribution of N pathways in the soil metagenomes. A neighbor-joining tree was constructed using 16S rRNA sequences (Materials and Methods) and includes all archaea and bacteria genera associated with N cycling sequences in the dataset. The outer circle plots the proportion of N cycle reads assigned to each pathway within the genus. The ammonia assimilation pathway is excluded, because it was found in all genera represented by at least 10 sequences. The inner circle indicates major classes and phyla. See Fig. S5 for a high-resolution figure with genus labels.