[AndrewC]

An increased mutation rate in a bacteria under stress generates genetic variation.

But that mutation rate is directed at specific areas at specific rates. That is not Darwinian. You missed this in Shapiro's article.

Darwin himself acknowledged this point in later editions of Origin of Species, where he wrote about natural "sports" or "...variations which seem to us in our ignorance to arise spontaneously. It appears that I formerly underrated the frequency and value of these latter forms of variation, as leading to permanent modifications of structure independently of natural selection." (6th edition, Chapter XV, p. 395).

[allmendream]

Error prone DNA polymerase has an INHERENT and INTRINSIC rate of error. A bacteria under stress upregulates error prone DNA polymerase and down regulates DNA repair enzymes. This causes the mutation rate to go up over the entire genome.