Re: Bacterial Evolution Question


uraniumcommit...@xxxxxxxxx wrote:

Some small percentage of bacteria are naturally more resistant to the
drugs. If the drug is administered for too short a time, the most
resistant ones will recover and restart the infection, but the second
infection will be of descendants of the resistant forms. Subsequent
adminsitration of the drug will be less effective in eradicating the
infection. This has nothing to do with 'evolution' per se, but rather
with selecting the more resistant forms. The 'evolution' occurs in the
mutations that make the bacteria resistant to start with. In nature,
those forms would typically be a small percentage. Anti-biotic drugs
are selected and tested against the bacteria for efficacy. Those that
has no efficacy are rejected. The bacteria do the same thing. The forms
that are susceptible die off, leaving those that are less so. It's
basically a war.

You're wrong to say that the development of antibiotic resistance by a
bacterial colony is not the result of real evolution - it is. You can
start with a completely clonal population of identical bacteria that
are all equally susceptible to a particular antibiotic and this colony,
if exposed to sublethal levels of the antibiotic, will evolve
resistance to that antibiotic in relatively short order via mutation
and natural selection. This, by definition, is Darwinian-style
evolution of a new function. It is just that this particular function
is at a very low level of functional complexity. That's why it works.
Higher-level functions, however, do not evolve so easily because of the
exponentially growing neutral/detrimental gap problem.

Sean Pitman
www.DetectingDesign.com

.

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