Interspecific vs intergeneric hybrids

[Stanley A. Gorodenski]

The thesis that hybridization between closely related species will be
rare because reproductive isolation will be selected for during the
process of speciation appears to assume the Biological Species Concept
(BSC). The example you gave seems to illustrate one of the problems with
the BSC. I like Templeton's Cohesive species concept better. According
to this concept, reproductive isolation is a byproduct of the cohesive
forces in a population (such as selection and genetic drift), not
something that drives speciation. Thus, no selection for reproductive
isolation is involved. As a result, one would not necessarily expect
that closely related species would have a higher degree of reproductive
isolation. 

Stan


Michael Gochfeld wrote:
> 
> hybrids was reported (maybe 30 years ago).  The idea was that interspecific
> hybridization was rare among closely related species since they had been
> selected for reproductive isolation during the process of speciation.  However,
> taxa in different genera (hence assumed to be less closely related) did not have
> the same pre-gametic selection for reproductive isolation.
> 
> Hence it was easier to detect hybrids among non-congeners than among congeners,
> and converseliy hybridization was not evidence that the parent species were
> congeneric.
> 
> Mike Gochfeld
> 
> Bill Yule wrote:
> 
> > Hi all.
> >    I think Chris brings up a good point: If two entities can hybridize in
> > the wild is that in itself sufficient to consider them congeneric?
> >   I'm not a taxonomist or an entomologist but I can't help but wonder if two
> > butterflies can mate and produce fertile offspring and you can still
> > consider them affiliated with different genera what exactly then does that
> > taxon (genus) mean?
> >
> >                                             Bill Yule
> > ----- Original Message -----
> > From: "Chris J. Durden" <drdn at mail.utexas.edu>
> > To: <leps-l at lists.yale.edu>
> > Sent: Wednesday, November 06, 2002 12:40 PM
> > Subject: Re: Cynthia
> >
> > > To me the occurrence of occasional wild hybrids between *V. atalanta* and
> > > *C. annabella* suggests that they should be considered congeneric and that
> > > *Cynthia* should be ranked as a weak subgenus of *Vanessa*.
> > > ................Chris Durden
> > >
> > > At 11:57 AM 11/4/2002 -0800, you wrote:
> > > >Hi Bill et al.,
> > > >
> > > >Cynthia resurrected by W. D. Field (1971, Smithsonian Contrib. Zool. 84)
> > > >for
> > > >cardui, kershawi, virginiensis, altissima, braziliensis, terpsichore,
> > > >myrinna, annabella, carye
> > > >
> > > >Vanessa ss. is for atalanta, tameamea, samani, indica, dejeanii
> > > >
> > > >Bassaris ss. for itea and gonerilla
> > > >
> > > >Lately, the monophyly of Vanessa + Cynthia + Bassaris  has been
> > > >supported by molecular and morphological cladistic analysis by Nylin et
> > > >al (2001, Biol. J. Linn Soc. 132:441-468), although they do not have an
> > > >opinion on whether the clade should be one genus or three.
> > > >
> > > >Cheers,
> > > >
> > > >Andy Brower
> > >
> > >
> > >
> > >
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