From: lbmkjm at yahoo.com (brian lee) on 2008.01.08 at 09:48:24(16932)|
Aloha. I think the best thing for you to do is to
look at Botany Online...it will help you on some of
the questions you pose.
In a nutshell, aneuploidy messes things up. In
humans, tumors and Down's Syndrome are examples. In
plants, death or deviant growth patterns are observed.
--- ted.held at us.henkel.com wrote:
> Dear List,
> I have managed to finish the latest Aroideana. It's
> probably a good thing
> for me this comes out only once a year as it seems
> like it takes me a year
> to read and digest what's in one. Being a lay
> person, some of the articles
> can be heavy-going. The one entitled "The Chromosome
> Numbers of the Aroid
> Genera", by Dr. Bogner, is a case in point. I am
> trying to sort out what
> the apparent promiscuity of aroids with regard to
> chromosome numbers might
> mean. Here are some questions?
> 1. Do all the plants within a given species have the
> same basic "X" number
> of chromosomes? Does this mean a species within the
> genus Landoltia, for
> example, might have a normal 2n chromosome count of
> 40 with haploid (2n =
> 20), diploid (2n = 80), etc., variations, but not 2n
> = 46? So if you have
> two plants, one with 2n = 40 and another with 2n =
> 46, do you know you
> have two different species?
> 2. Can plants with different chromosome counts be
> cross fertile? Can a 2n
> = 40 plant produce viable seed with its own diploid?
> How about with a
> plant in the same genus with a chromosome count of
> 2n = 46?
> 3. What happens when a plant messes up and undergoes
> Aneuploidy is defined in the text as when some type
> of evolution takes
> place where the offspring end up with a few extra
> chromosomes here and
> there. Doesn't this mess up the plant? If not, why
> 4. Similarly, there is a term called dysploidy where
> a few chromosomes
> don't make it into the new plants, or where old
> chromosomes get pieces
> chewed off, somehow. Don't plants need at least a
> portion of the
> information contained in the chromosome arms?
> Doesn't this mess up the
> plant? If not, why not?
> 5. Can a plant that has experienced aneuploidy or
> dysploidy produce viable
> seed with a normal-count plant? Or does the plant
> have to reproduce
> vegetatively for a while until there is another
> receptive brother or
> sister with whom to mate?
> 6. How much messing around with chromosome numbers
> does it take before the
> morphological differences are large enough to
> produce a new genus?
> Please take pity on me. When I went to school all
> this was very new. Come
> to think of it Darwin was new stuff back in those
> > _______________________________________________
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