Table 1

Genomic substitution rates (U) per generation in bacteria

SpeciesGenome size, bpSubstitution rate*Generations per yearU
E. coli 4.7  ×  1064.5  ×  10−9100–3000.0001–0.0002
Buchnera 6.6  ×  1058.2  ×  10−930–500.0001–0.0002
  • * Substitution rates are calculated per synonymous site per year based on externally calibrated divergence times. 

  • Generation times are based on those reported for natural populations of E. coli (3739) and Buchnera (19, 4042). 

  • Laboratory studies of E. coli and other DNA-based microbes yield an average genomic mutation rate of 0.003 (20, 22).