Maximum likelihood tree of bacterial 16S rRNA sequences.

<p>Major phyla, represented by triangles whose area is proportional to the number of sequences, were tested for lineage-specific differences using UniFrac. The lineage-specific analysis tests for each lineage whether the sequences have a different distribution among environments than does the tree overall and therefore highlight which lineage contributed to the differences observed (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089531#pone-0089531-g003" target="_blank">Figure 3</a>). Nodes A-D are significantly unevenly distributed between environments; <i>p</i>-values are: <i>p</i>_A = 1.1×10⁻⁵, <i>p</i>_B = 2.8×10⁻³, <i>p</i>_C = 5.8×10⁻⁴, <i>p</i>_D = 1.3×10⁻³, <i>p</i>_E = 1.0×10⁻², <i>p</i>_F = 1.1×10⁻¹⁹. Pie charts connected to these nodes represent the distribution of environments within each lineage. Numbers adjacent to each node represent aLRT statistics (SH-like supports); only support values >0.50 are shown. Scale bar for branch lengths (expected number of substitutions per site) is shown.