"I hope you now understand my confusion. I was assuming that 'appearance'
and 'existence' could be used interchangably. Is there some technical
reason to distinguish these terms, or was your original statement somewhat
misleading? No offense, but it seems you are now saying something very
different from your original statement."
Your confusion may stem from the fact that you are thinking of the physical
mutations whereas I am referring to the functions produced by the protein
products of those mutations. The mutations can come and go, but for the
function to have any importance within a population, it has to become
permanent, and for it to become permanent there must be something for it to
act on. My choice of words in the original post may not have been the
best; were I to rewrite it I would probably say something like "functions
that never were population traits, never could be population traits". But
my overall point is that these functions represent new information,
especially if they are to respond to man-made situations that never existed
before in nature and never could exist in nature.
"Perhaps you could point me to a reference on one of these studies. If
such an experiment is done, and if the toxin is introduced into a
population of bacteria, none of which have the resistance function, don't
they all simply die?"
I'll have to get back to you on the references. However, the experiments
are not done with levels of toxin so high they kill everything. The level
generally used is an amount that on average should kill 50% of the
population. Those that do not die are naturally hardier, so they are able
continue living despite the toxin's harmful affects, but they have no
special resistance, just stamina. They won't live as long as they would in
the absence of the toxin, nor will they be as healthy, but they can produce
progeny.
Another way to do the experiment is to expose the progeny to the toxin
rather than the parents. In this case levels high enough to kill
everything are used; progeny who had the mutation and so are resistant
would survive.
"To me, the argument that such a function, present by mutation BEFORE the
introduction of the toxin, 'CAN be just as easily lost' in the absence of
the toxin to provide a selective pressure, is QUITE DIFFERENT from the
absolute-sounding claim that the function 'could NEVER exist'."
I would not disagree, but in the C/E a certain amount of rhetoric is to be
expected when presenting ideas. I was trying to get across the idea that
the functions produced by the mutations were to handle toxins, materials
and conditions that could not be found in nature; in fact, could never be
found in nature. As such these were new functions and so represented new
information. I just didn't phrase it in the best way.
Kevin L. O'Brien
klob@lamar.colostate.edu