Re: Breeding and speciation (was food labeling)

Russ Bulluck (lrbulluc@unity.ncsu.edu)
Thu, 09 Sep 1999 08:44:53 -0400

"Wilson, Dale" wrote:

> Jim,
>
> > I do not believe any consensus exists among
> > scientists as to how much genetic divergence
> > is needed to name a new species.
>
> It seems like there is consensus that calling something a different species
> hinges on reproductive isolation. The isolation may result from actual
> reproductive incompatibility (ie, genetic difference) or spatial-temporal

<snip>
I agree. One species concept (especially for bacteria) states that genetic
diversity (measured by bands of DNA present on gels from PCR electrophoresis)
must have at least 70% compatability. However, DNA from one species of bacteria
can get into another species through conjugation,

> In any case, the meaning of "species" depends on the context. In the
> breeding context, only cross-compatibility is relevant.
>
> Dale

Species also depends on the scale on which you look. for _most_ multi-cellular
organisms, interbreeding to produce viable offspring is a major component of the
"Species Concept" (Actually the Concept of the "Species Concept" is often taught
in different classes, and differs to some extent in every class!). However,
with single celled organisms, and some multi-cellular organisms (esp. fungi),
sexual reproduction is rare or absent. . .

The correct answer the the original question is. . . "It Depends. . . "

--
Russ Bulluck
Ph.D. Candidate
Department of Plant Pathology
North Carolina State University
PO Box 7616
Raleigh, NC  27695-7616


http://www.cals.ncsu.edu/plantpath/Personnel/Students/webpage.htm


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The soil population is so complex that it manifestly cannot
be dealt with as a whole with any detail by any one person,
and at the same time it plays so important a part in the soil
economy that it must be studied.
--Sir E. John Russell
The Micro-organisms of the Soil, 1923
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