Maximum likelihood tree of recA amino acid sequences. The tree includes Sargasso Sea metagenomic data and predicted proteins from cultured isolates of Pelagibacter. The sequence data was derived from Vergin et al., 2007 , with the addition of a sequence from strain HTCC7211, which was recently isolated from the Sargasso Sea. All other HTCC strains are from the coastal Pacific Ocean. The non-HTCC numbers correspond to the fragment identifier in the Sargasso Sea data set. The scale bar indicates substitutions per nucleotide position.