Fig. 5.

Phylogenetic distribution of genera encoding specific pathways. The neighbor-joining tree was constructed using 16S rRNA data (Materials and Methods). The relative abundance of genera associated with (A) N fixation and (B) dissimilatory nitrite reduction to ammonium. Within a pathway, the proportion of sequences associated with each genera was calculated for each sample. The proportions were averaged across libraries within each location and then averaged across the 10 habitat types (to provide equal weighting to the habitats). The heat maps give the relative frequency by habitat for the 15 most abundant genera associated with each pathway. See Fig. S6 for plots of all pathways with genus labels.