Figure 3.
Universal tree of life based on small-subunit ribosomal (SSU) RNA sequences. Selected sequenced Archaea are highlighted and have their genome sizes indicated. All known methane-producing organisms are members of the domain Archaea (shown in green). TheMethanosarcineae are the most metabolically and environmentally diverse methanogens. They are also members of the lineage giving rise to the anaerobic sulfate-reducingArchaeoglobus fulgidus (shown in yellow) and the aerobic halophilic Halobacterium species (shown in blue).
