Re: Re: HYB: ploidy - speculation

>Donald, since you've got your copy handy, does the article compare
>'kinds' of chromosomes among diploids (i.e., 24 chromosome pallida &
>variegata)?

Yeah, sorta.  It talks about metacentric chromosomes - used for those with
either median or submedian centromeres.  And it talks about 'acrocentri' as
those with nearly terminal centromeres.  It uses drawings of the chromosomes
for species.  One of the best illustrations is of I. attica (8 chromosomes),
I. pseudopumila (8 chromosomes) and I. pumila (16 chromosomes).  All the
different chromosomes illustrated by length and centromere on an idiogram
for each one.  Thus you can see that I. pumila consists of all similar
chromosomes as those contained in attica and pseudopumila.

For those challenged by technical terms, as I am, near as I can tell a
centromere is that part of the chromosome that is all squeezed, nearly
giving it an upper and lower half.  So some are squozed in the middle
(median) and some are squozed near the end (submedian).  From the article I
gathered that many arils tend to have all submedian chromosomes, so they
don't match up readily with other bearded irises that consist of more median
chromosomes.  In terms of evolution, the submedian is newer.  Makes sense
since arils had to adapt to some pretty harsh climates in order to survive.

I am going to quit this now.  It's an area that I struggle with and my grasp
of it is very poor and I'd better leave it to those whose knowledge far, far
exceeds my own.  It's awfully hard to play scrabble with alphabet soup and
that's a proximate picture of my brain at the present time.

Donald Eaves
donald@eastland.net
Texas Zone 7b, USA



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