In article <3A3B104D.E818204 at mediaone.net>,
George Hammond <ghammond at mediaone.net> wrote:
[...]
> >
> > It's a common practice in biology to use genetically identical
> > organisms (and not only in plants) in an experiment to avoid genetic
> > variation as a confounding factor. For example, most lab strains of
> > mice are inbred strains that are gentically identical to one another
> > (within a strain).
> >
> > Nick
>> GH: You're kidding.... how "identical" is identical, as far as
> mice are concerned? Do you mean "EXACTLY genetically identical"?
Yep. They have been deliberately inbred for many generations to make
them genetically identical. This is basic genetics. If you keep "back-
crossing" (child and parent breeding) and inbreeding long enough, you
can guarentee lack of genetic variability among offspring. Mice from
*different* strains are considerably different from each other, however.
>> Also, there are "parthogenetic" animals who asexually
> reproduce, so that are all genetically identical.
> Small animals, some annelids, flatworms, aphids, and
> I've heard, some large animals like fish and lizards
> reproduce asexually and form genetically identical
> schools, tribes, families etc. Is this true?
> >
You can cut some flatworms in half and each half will grow a new worm.
I don't know if this is used in the "wild" as a form of reproduction.
Same for starfish, too. There is also a lizard species that reproduces
parthenogenetically, but I don't remember the details. Field biology is
not my specialty.
BTW, the word "clone" is derived from a Greek word meaning "branch"
or "twig." It refers to the ancient practice of using grafting to make
a tree that that is descended asexually ("cloned") from another.
Nick
--
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Nick Theodorakis
nicholas_theodorakis at urmc.rochester.edu
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