Re: RE: HYB ploidy - oops

Now that is very interesting.  The second note arrived before the first one
(and they were several minutes apart).  So,  at the risk of a repeat, here
is the first one again.

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I don't remember the exact quote, but there was recently a comment about
waiting a long time to run across the rare unreduced diploid gamete in a
diploid to get pairing with a diploid gamete from a tetraploid.

This is just a suspicion, but I do suspect that one would not have to wait
long at all, in fact I suspect it would be a rather common event.

Plants produce lots of gametes (especially pollen, in the case of Iris).
Unreduced versions shouldn't be rare at all, accidents in cell division
happen all the time.  So, when pairing gametes from a diploid with those of
a tetraploid, it would seem to me that it would be almost inevitable that
some small percentage would come out as fertile tetraploids on a regular
basis (assuming the base compliments are all compatible, as with a diploid
base 12 x a tetraploid base 12).

This would seem to be backed by the fact that in early crosses of I.
pallida, (and fewer, but still notable numbers of I. (pallida x variegata),
and I. variegata) with tetraploid species, there were an amazingly (in my
mind) high number of fertile tetraploid clones produced.  The hybridizers
may have gone through hundreds of progeny, perhaps thousands, to find them,
but none-the-less, there were quite a few of them produced, and they were
the foundations of the TB strains that we grow now.

Yes it is rather rare to have a tetraploid in a diploid wild population,
and rare to have a hexaploid or octaploid in a tetraploid population, but
it is not unheard of.  I think the higher the ploidy, the more rare it is.

However, unreduced gametes are probably the main (only?) way that wild
tetraploids came to be.  It is rare that unreduced gamete would meet
unreduced gamete in the wild, but it does occur.  More often an unreduced
gamete would pair with a normal gamete to produce a sterile (or nearly
sterile) triploid, which would be a dead end and produce few

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