Fig. 6.

The fraction of operons with significant changes in codon selection increases with phylogenetic distance. (A, B) Pairwise values are reported for Escherichia coli, Escherichia fergusonii, Salmonella enterica Typhimurium, Salmonella enterica Arizonae, Citrobacter rodentium, Citrobacter koseri, Enterobacter cloacae, and Cronobacter turicensis. (C, D) Pairwise values are reported for E. coli, E. fergusonii, S. enterica Typhimurium, S. enterica Arizonae, C. rodentium, C. koseri, E. cloacae, Enterobacter sp. 638, C. turicensis, Dickeya zeae, Klebsiella varicola, Klebsiella pneumoniae, Pectobacterium wasabiae, Erwinia amylovora, Erwinia tasmaniensis, Yersinia enterocolitica, and Serratia proteamaculans.