Correlation between dnaE2 gain-and-loss and GC content variation. In the Genus Shewanella, two bacteria (red) have higher GC content, which correlates well with the presence of the dnaE2 gene (A). Mycobacterium leprae has a lower GC content because it has lost the dnaE2 gene (B). The phylogenetic tree was constructed using the NJ method of MEGA 4.0 and 16s rRNA sequences. Bootstrap values (>50) are labeled.