polyploidy

Janice M. Glime jmglime at MTU.EDU
Fri Sep 3 11:00:00 EST 1999


Wow,
  Another chance to speculate today.  I don't know about plant traits that
may lead to more frequent apomictic events, but it seems that plants would
have a better opportunity to survive such events.  Plant structural
development is less complex, without the need for multiple organ systems
to be coordinated, and this may play a role, but I think the success may
lie in the ability of gametophytes, especially in lower plants, to
survive.  2n gametophytes can hang around for a long time before
successfully mating, but when they finally do, the offspring are likely to
survive.  In fact, this successful mating can often create instant species
and may evolve a monoicous (bryophyte term for a gametophyte with both
sexes) species from two dioicous ones.  The plants need only reproduce at
the same time and recognize (or not reject) each other chemically, whereas
in animals the change in ploidy could affect behavior in ways that reduce
mating.  And plants can succeed at triploids and reproduce vegetatively
for many years awaiting that single successful event that permits them to
complete successful sexual reproduction.  Animals usually don't have that
ability. 

  Now, if these reasons are valid, we should be able to find polyploid
examples among animals that are simple in construction and/or able to
exist by vegetative reproduction through a long period of time.  Does
anyone know of such examples?  Maybe we need to invite the biolab folks to
join this discussion.

Janice
***********************************
 Janice M. Glime, Professor  
 Department of Biological Sciences
 Michigan Technological University
 Houghton, MI 49931-1295
 jmglime at mtu.edu
 906-487-2546
 FAX 906-487-3167 
***********************************


 > > >Hello,
> >
> >I am going over some evolutionary theory in my plant bio class, and it
> >occurred to me that, although I know that polyploidy occurs much more
> >often in plant speciation events than in animals, I do not know *why* this
> >is true.  Is it a quality of the plant genome itself, or a result of
> >products similar to colchicine (that can prevent reduction-division during
> >meiosis) being more common in plant cells, or because of some other
> >factor?
> >
> >Any leads (citations, etc.) on this topic would be appreciated!  
> >
> >Thanks,
> >Dana
> >
> 
> Dana,
> I've always assumed it was simply that animals do not tolerate aneuploidy
> and wind up dead.  That leaves the question of why plants can tolerate it
> and animals can't.  I've often wondered about that.
> 
> 
> Dr. Gary Coté
> Assistant Professor
> Department of Biology
> Box 6931
> Radford University
> Radford, VA 24142-6931
> 
> Ph: 540-831-5630
> Fax: 540-831-6615
> email: gcote at runet.edu
> http://www.runet.edu:8800/~gcote/
> 




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