Figure 2. An unrooted ITS-based phylogenetic tree of phylotypes in the Red Sea’s water column.

The tree was generated using 1,750 ITS sequences, which included representative from 975 OTU clusters derived from our clone sequences, that were derived from specific 16S subgroups (S). Branches with significant bootstrap support from trees inferred using both maximum parsimony and neighbor-joining algorithms, are shown with open (≥50%) or closed (≥70%) circles. Branches that constitute potentially novel phylotypes are shown with dashed lines. Sequence nametags were omitted for clarity; a detailed phylogenetic tree is provided as Figure S5.