What is Aneuploidy?
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. 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,
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 days.
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