From: Aaron Davidson (ajd@gpu.srv.ualberta.ca)
Date: Wed Mar 22 2000 - 01:27:56 MST
M. E. Smith Wrote:
>An example he gives is a bacteria that is unable to
>absorb lactose quickly undergoing mutations that allow
>it to absorb lactose when deprived of anything else to
>eat, and ONLY undergoing said mutation in that
>situation (that is, a control colony of the same
>bacteria does not undergo the same mutation in an
>environment where it has food it can absorb).
This argument sounds like the type posed by creationists.
How was it determined that the food-supplied population never
underwent the same mutation? Was every single bacteria genome
examined to see if it had the mutation?
The reason the population given abundant food does not "develop" the
absorbtion of lactose mutation is because there is no selection
pressure to do so in this case. It is most likely that several
specimens in the fed population *did* have this mutation, but since
there was no need for it in their environment, it did not flourish in
the population. In fact, it may even have a negative impact on
survival (except when starvation is an overriding pressure)
The population given only lactose to eat, will of course become full
of specimens with the mutation, since in that case it is selected for.
Speculating, It could be the case that past evolution has engineered
the bacterium's genome to actually increase the chance of that
specific mutation when in such environments. So the apparent
"accelerated beneficial mutations" may actually have been evolved
over a much longer time scale. It only appears to be evolving too
fast.
-- +-------------------------------------------------------------------------+ | Aaron Davidson <ajd@ualberta.ca> http://www.cs.ualberta.ca/~davidson/ | +-------------------------------------------------------------------------+
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