Understanding the role of recombination and polymorphism in the genetic diversity of an organism, bacterial evolution and emerging pathogens is vital in developing therapeutic or vaccine strategies for a disease [12].
The demonstrated proportionality between Vip and Vg then suggests that the evolution speed is proportional to the isogenic phenotypic fluctuation, as is also supported by an experiment on bacterial evolution in a laboratory[17] and confirmed by simulations of a reaction network model of a growing cell[18].
Although the use of relaxed clocks and more realistic models of sequence evolution can mitigate the problem of rate heterogeneity, the lack of robust calibration points remains a major challenge to established a timescale for bacterial evolution.
There appears to be no panacea when attempting to assemble a timescale for bacterial evolution.
A qualitatively similar time dependence of fitness and substitution rate has been reported in a long-term bacterial evolution experiment by Barrick et al. (2009).
Dr. W. Ford Doolittle, an expert on bacterial evolution at Dalhousie University in Nova Scotia, said the lateral transfer of bacterial genes into the human genome was possible but the consortium's method of trying to prove it was "awfully incautious".
The rapidly growing wealth of genome sequence data from closely related bacteria sheds a new light on bacterial evolution and will become an increasingly important source of knowledge in the near future.
Gene degradation and gene deletions also have been shown to play a critical role in bacterial evolution, particularly when organisms with a broad niche specificity adapt to narrow and specific ecological niches [ 5, 16].
If 16S rRNA genes cannot serve as a reliable chronometer for bacterial evolution, perhaps there are other genes that evolve in a more consistent manner.
