Figure 1. Maximum-likelihood phylogenetic tree of proteobacterial 16S rRNA gene sequences from Atlantis Massif samples.

The environments from which microorganisms originated from are color coded (see key). Branch points supported by all phylogenetic analyses (quartet puzzling support values ≥90%) are shown by •; branch points supported by most analyses, but with less confidence (quartet puzzling support values 50–89%) are shown by ○; branch points without circles are unresolved (quartet puzzling support values <50%). Sequences <1200 nucleotides in length were inserted using the ARB parsimony insertion tool and are indicated by *. This proteobacterial ML tree was constructed with 1,000 puzzling steps. Prochlorococcus marinus (NC_009976) served as the outgroup (not shown).