>> As difficult as it is, public debate on GMO use, and other
>> agricultural issues is essential in order to formulate public
>> policy...
> For GMOs, once they are out, it is extremely difficult to
> recall them. Risk/benefit analysis may work with chemicals or
> nuclear power, which have half-lifes, but GMOs have doubling-times,
> and the risks double as the GMO population doubles. Given enough
> doubling-times, even infinitisimally-small risks will eventually
> approach near-certainty.
What you are implying is probably true for a few (currently theoretical)
situations. For example, the industry won't develop herbicide resistant
sorghum for just this reason. The threat comes from expression of the
construct in the context of a particular plant/environment system. Wild
relatives such as johnsongrass and shattercane competitive in the
agroecosystem create this risk.
But in the absence of a wild relative and a niche conferring competitive
advantage, it is hard to imagine what you mean. After all, the components
of these constructs (antibiosis genes, promoters) have been floating around
in the environment for millions of years. If combinations of these are so
competitive, so virulent, how come we don't see them?
The truth is that these terrible life forms ARE with us, but we accept them
because we regard them as "natural." The competitive, fecund, predatory
species have been honed by millions of years of evolution to be as powerful
as they can be. The important new chip in all this is the agroecosystem
(not transgenics). This has led, for example, to the dominance of a small
set of aggressive species adapted to colonize disturbed habitats (our common
nemesis in agriculture). I maintain that the risk that we can produce by
dinking around with genes and promoters (accelerating evolution) is risk to
the agroecosystem, not nature at large.
So the risk of making and dispersing Roundup-ready SORGHUM would be crossing
into, and increased fitness of weeds that are already dangerous in the
agroecosystem. But expression of such events would be expected to DECREASE
fitness in environments other than the row-crop system. Over-expression of
genes has a cost.
But the thread was about Bt corn. In what way to do you think Bt corn is
going to get out and proliferate across the landscape?
Dale
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