Re: [asa] (fruit flies???) A Message from the RTB Scholar Team

From: Freeman, Louise Margaret <lfreeman@mbc.edu>
Date: Tue Apr 22 2008 - 20:04:44 EDT

If you rounded up all the domestic dogs in the world and artificially selected only great Danes
and miniature dauchshands to survive by euthanizing every other breed, many would argue
you'd have two separate species, in that they'd be physically unable to interbreed.

Here's another example of a species created in a lab. I learned this in my botany class in 1984;
it was taught by Dr. Eloise Carter, who did a lot of the research.

There are a number of species within the Talinun genus. Two species: Talinum mengesii and
Talinum parviflorum have 24 chromosomes. They can hybridize, the the offspring are sterile,
so they are clearly different species by any reasonable definition. Another plant, Talinum
teritafolium, has 48 chromosomes; studies had shown that half of them were identical to T.
mengesii and half to T. parviflorum. It is theefore thought that T. teritifolium arose when a
sterile hybrid of the other two species underwent a spontaneous polyploidy event (doubling of
the chromosomes), creating a fertile plant that could self-pollinate. A big piece of
experimental evidence to support this model came scientists took the sterile
mengesii/parviflrum hybrid, treated it with the drug colchicine to induce polyploidy and
produced a plant that not only looked like the wild T. teritifolium, but could interbreed with it
and produce viable offspring.

This seems to me to be a great example of not only creating a new species in the lab but doing
by imitating the very event that seems to have produced (via polyploidy and natural selection
for fertile plants) a new species in the wild.

__
Louise M. Freeman, PhD
Psychology Dept
Mary Baldwin College
Staunton, VA 24401
540-887-7326
FAX 540-887-7121

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Received on Tue Apr 22 20:05:57 2008

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