Simulations of the tradeoff dynamics via random nucleotide mutations. A, B, simulations for two genomes (Nocardiopsis dassonvillei subs. dassonvillei DSM 43111, GCNAT = 72.7; and Streptobacillus moniliformis DSM 12112, GCNAT = 26.3) with distorted codon bias. A, changes in the GCCB/GCNCB pairs related to the tradeoff. B, the increase of the genomes’ codon entropy in relation to the distribution of entropies in all genomes. C and D, simulations of mutations in 1364 natural genomes; the simulation starts at points marked by filled circles and continues along the lines. The traces are colored by average amino acid depth C, changes in the GCCB/GCNCB pairs related to the tradeoff. D, behavior of the codon entropy.