Re: Breeding and speciation (was food labeling)

James Kotcon (jkotcon@wvu.edu)
Wed, 08 Sep 1999 16:21:52 -0400

I do not believe any consensus exists among scientists as to how
much genetic divergence is needed to name a new species. In some bacteria,
a single gene difference will lead to a new species name, while in other
bacteria, as much as 30 % of the genome may vary within the same "species".
Humans and chimpanzees share 99 % of our genome, so that 1 % difference
appears to be biologically and evolutionarily significant.

Jim Kotcon

At 11:37 AM 9/8/99 -0500, you wrote:
>Phil,
>
>> When would corn or soybeans cease to be corn and soybeans?
>> When one foreign gene is added? or two ? or ten percent?
>> fifty percent? or when they finally don't look like corn or
>> soybeans?
>
>Species are integrated systems of great complexity. No one understands
>enough biology to engineer them on a systems level. Corn has something like
>60,000 genes. Crop species are mainly manipulated by conventional breeding,
>by sexual recombination of diverse types and selection of progeny. Compared
>to the great changes that have apparently occurred over millions of years
>via natural selection, all the changes we make are pretty minor. One
>interesting example, and seeming exception is corn. The form and growth
>habit were very much changed (apparently derived from teosinte) through
>selection by humans several thousand years ago. Probably, rare mutants were
>selected and propagated and this gave rise to what we call corn.
>
>No transformation of plants this dramatic has occurred yet in the modern
>period, so there are no regulatory precedents.
>
>Dale
>
>
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