Comparison of CGS and GC methods. (A) Discrimination values based on CGS scores and GC scores were calculated using as targets the genomes of Group 1 cyanobacteria (□) Ana, (∆) Mar, and (○) Syn; 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. Each point is the average of three trials. The values in the dotted box uses contaminating genes from (-) Gvi (GC% of 62%), (♦) Gvi, Syw (GC% of 59%), and Cya (GC% of 60%), (□) Pmm (GC% of 31%). (B) The same GC scores as in panel A are shown related to the difference in GC% of the donor and target genomes. (C) The same discrimination values as in panel A are shown related to the difference in GC% of the donor and target genomes. The identities of the genomes and values of both methods are provided in Additional file2.