If so, then how is GE different from nature? I have been thinking
for some time about the issue of scale - in both space and time. In
nature, let's imagine that an individual virus manages to insert
itself, de novo, into another organism - say an individual squash
plant, and in so doing, affects the fitness and survival of that
individual plant. Sometimes good, sometimes bad, - the whole natural
selection thing over hundreds, thousands....etc. years. But the key
issue is that it is a *point* process occurring in a single
individual, and the outcome of that single event is acted upon by
selection over a very long time.
But most importantly, the outcomes are not limited to that individual
squash plant, but to all the other organisms and ecological processes
affected by that pivotal squash plant. The affected would include
the pests, predators, herbivores, and other neighboring plants of
that individual plant and its progeny, as well as the decomposer
organisms that break down the residues and so on. What matters, in
an ecosystem sense, is not just the fitness of the squash caused by
the individual genetic event of inserting viral genes, but everything
else that follows. Nature has time to adjust, for co-evolution in
affected organisms to occur, and for the ultimate fitness of the
trait to be tested.
Understand that I am willing to assume zillions of examples of this
kind of thing are happening all the time, but in each case, it is a
point source of genetic variation, analogous to a mutation, and the
ultimate outcome (favorable, unfavorable) takes many many years to
manifest itself. The degree to which "foreign" genes exist today, in
our own genome and that of other ife forms is a reflection of the
winners - the ones that managed to hang together for whatever reason.
Now, how is this different from GE? Compare the tortuously slow and
convoluted process of natural selection acting on a point source of
genetic variation, throughout an ecosystem, with the instantaneous
entry of a single, novel genome over millions of hectares of
agricultural land. Instead of a single individual plant, responding
to multifaceted selection pressure exerted by the weather,
neighbors, pest, herbivores, etc., we have zillions of identical
plants all doing the same thing, growing the same plant pesticide,
pumping the same, novel active Bt toxin in the soil all at the same
time (novel because it is in the active form, not a precurser).
There is no time for nature to sort things out, to screen out the
deleterious and encourage the favorable. I wonder if this might not
be a key difference between gene movement in "nature" and via GE.
Ann
ACLARK@plant.uoguelph.ca
Dr. E. Ann Clark
Associate Professor
Crop Science
University of Guelph
Guelph, ON N1G 2W1
Phone: 519-824-4120 Ext. 2508
FAX: 519 763-8933
http://www.oac.uoguelph.ca/www/CRSC/faculty/eac.htm
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