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Re: GM Rating



Trevor wrote;
>I agree with your sentiment.  It would be very helpful to create some
>kind of scale of "rate of genetic shift".
              :
>but attempts to identify a measured, natural threshold
>of genetic change are still very much in their infancy.

I am not a geneticist and so perhaps do not appreciate the problem.

Through DNA we appear to be able to trace the family tree of species back
to common ancestors. Can this not be used to produce an average natural
rate of genetic change over millions of years ? Perhaps different branches
of the tree would have different rates of change but, over such large
timescales, I would not be surprised to find some common Golden number.
This number might be the benchmark number for natural change.

We can also look at the modern animal breeder or horticulturist. There must
be some limit to the amount of genetic change that they can deliberately
induce, in a single generation, using traditional methods.

If we then assume a genetecist wants to modify species with DNA 'A' into
species with DNA 'B' can we not at least make an estimate of the number of
generations difference between the two ?

>In canada, the Canada
>Food Inspection Agency is creating a database of genetic modifications
>in food crops since the late 1800's.  I will try to devise a methodology
>of rating the severity of each shift in strain.  However, the likelihood
>of a given genetic shift is fundamentally effected by how widespread the
>crop is; I will have to arrive at some way to neutrally deal with the
>reality of monocultures.  

Can't you turn you problem on its head and use monocultures to advantage as
a means of measuring random genetic drift ?

Regards



Robert
Robert@tiamat.sonnet.co.uk