On Thu, 5 Aug 2004 21:40:25 +0100, Kay wrote:

In article , Rodger Whitlock
writes
On Thu, 5 Aug 2004 13:50:40 +0100, Kay wrote:


But there isn't any genetic variability, surely? So you're not selecting
in that sense if you propagate vegetatively?...

There is some genetic variability, if I can trust my reading.
Some authors claim quite a lot, but I have my doubts about that.
(I've seen serious claims that the genetic variability among the
twigs of one apple tree is comparable to that among a similar
number of seedlings of the same apple.)

Doesn't that make a mockery of vegetative propagation of garden
varieties?

The text I referred to was written in the context that many apple
cultivars were at one time propagated by seed -- they were seed
strains, rather than clones. Naturally, such strains would have
come fairly true to type.

And genetics is a pretty complex subject.

OK - well, I'm at the first-base level of reading how DNA is replicated
during cell splitting so each cell has a copy of what was in the
parental cell. Where is the variability coming from? Mistakes in
copying? Selective activation and deactivation? Both?

Isn't selective activation and deactivation different from genetic
variability - ie the two bits can be genetically identical but have
different genes expressed?

If you reach a full understanding of all this, you're a better
man than I am, Gunga Din.


--
Rodger Whitlock
Victoria, British Columbia, Canada
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