Comparison of effectiveness of CGS method vs other methods. Discrimination values determined by CGS, codon bias, W8, and modified W8 were calculated using as targets the genomes of Group 1 cyanobacteria (□) Ana, (∆) Cwat, () Mar, (○) Syn, and (◊) Ter; of Group 2 cyanobacteria (+) Pma, (-) Pmt, and (×) Syw; and of (♦) Tel, contaminating them to a level of 3% with the same genes from up to 25 different organisms. (A) Comparison with Codon Bias (CB). The values in the dotted box were obtained from cases in which contaminating genes were drawn from Gvi (GC% of 62%), Syw (GC% of 59%), and Cya (GC% of 60%). (B) Comparison with W8. The values in the dotted box were obtained from cases in which contaminating genes were drawn from from Gvi (GC% of 62%) and Syw (GC% of 59%). (C) Comparison with the W8 method modified to exclude contaminating genes. The W8 was modified so that genes artificially added to a genome did not contribute to the calculation of the reference set of octamer frequencies. The identities of the genomes and values for all methods are provided in Additional file2.