FIG. 6.

Neighbor-joining tree showing taxonomic positions of mcrA gene sequences cloned from coastal marine sediments. Numbers in parentheses indicate the number of clones obtained for each sequence. Bootstrap values (percentage of 200 trials) for branch points are indicated when >50. Bar, 0.05 substitutions per sequence position. The presence of a particular OTU in carbon-amended (open symbols) and unamended (closed symbols) treatments are indicated for both April (circles) and August (triangles) directly adjacent to the OTU name.