Donald Forsdyke  wrote:

> john_SPAM{at}wilkins.id.au (John Wilkins) wrote:
> > Donald Forsdyke  wrote:
> > 
> > > The article "Polymorphism for hybrid male sterility in
Drosophila"
> > > should not be lightly dismissed. It is part of a growing literature on
> > > Haldane's rule that casts doubt on the idea that speciation has a
> > > genic origin. Naveira and Maside (1998) even go so far as to suggest
> > > that "hybrid male sterility results from the
...[introduction] of a
> > > minimum number of randomly dispersed factors" that
include "factors"
> > > in non-coding DNA. They suggest that "a new paradigm is emerging,
> > > which will force us ... to revise many conclusions of past
studies."
> > > 
> > > For more on this see:
> > > http://post.queensu.ca/~forsdyke/speciat2.htm
> > > 
> > > Sincerely,
> > > Donald Forsdyke, Department of Biochemistry,
> > > Queen's University, Kingston, Canada
> > 
> > Donald
> > 
> > Can you elucidate on this? What exactly does it mean that speciation
> > does not have a genic origin? So far as I have been able to ascertain,
> > speciation often does not have a *selective* origin in the literature,
> > except in sympatric cases, but how could it not be genic? Is this a
> > counter-argument to Wu's "speciation genes" account (in
which case I
> > think what is meant is that there are no special genes that *cause*
> > reproductive isolation, but of course reproductive isolation will result
> > from - in part and eventually - incompatibilities in genes)?
> 
> Dear John,
> 
>                    There are two general hypotheses for the initiation of
> reproductive isolation (i.e. initiation of divergence into distinct
> species), these are genic and non-genic (otherwise known as chromosomal).
> The latter was most clearly articulated in the 20th century by Richard
> Goldschmidt and Michael White and, for a while, was given some support by
> Stephen Jay Gould.
> 
>                   So to your question, how could it not be genic, I refer
> you to the works of these authors - especially Goldschmidt 1940. Eventually,
> of course, genic differences between two species appear and may contribute
> to the process of reproductive isolation. But the key issue is the
> initiation of reproductive isolation. Here non-genic hypotheses are still in
> contention, as I hope I clarify in my new JTB paper (see URL above).
> 
I shall read that paper when I get the chance. I understand what you
have called "non-genic" to mean "karyotypic", in the sense of MJD
White's "stasispatric" mode of speciation in sympatry. This, and
polyploidy, appear to be the sole processes that can generate new
species rapidly in a manner approximating Goldschmidtian genetic
rearrangement, so far as I know. But I would not have connected
Goldschmidt to White in that way, myself. The only similarity lies in
the speed of speciation, or rather of reproductive isolation, because
White's mechanism and polyploidy, whether allo- or auto-, don't
guarantee ecological adaptation the way Goldschmidt expected his
rearrangements would, as I, an amateur, understand it.
-- 
Dr John Wilkins
john_SPAM{at}wilkins.id.au   http://wilkins.id.au
"Men mark it when they hit, but do not mark it when they miss" 
                                               - Francis Bacon
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