Hybrid Speciation

[Don McAllister]

Hybridisation per se does not indicate that the two entities are conspecific.
Hybrids can be sterile.  Hybridisation with fertile offspring can be so rare
that there is no significant genetic interchange between the two species which
are thus able to maintain their distinctions.  Hybridisation may occur when the
environment is severely disturbed by humans or where the numbers of one species
are so depleted by humans that there is little opportunity to find a mate of
the same species, but be absent in undisturbed areas.  About 1% of the sucker
family, Catostomidae (a fish family) are saide to be hybrids in the U.S., but
the species remain distinct.

don

Curtis Clark wrote:

> At 11:53 AM 4/17/98 +0000, ROGER HYAM wrote:
> >If a cross occures between sister taxa then it suggests that these
> >taxa should be considered as a single entity - how could we show that
> >these two taxa (OTUs in our analysis) aren't segregates of a larger
> >taxon? 'Hybrids' of this type should not be formally recognised.
>
> Even if the hybrids are sterile?
>
> And consider the following case:
>
> A--+
>    +--+
> B--+  +----
>       |
> C-----+
>
> By your measure, a hybrid between A and B would demonstrate that they are
> conspecific, but a hybrid between A and C, since they are not sister taxa,
> would be a hybrid. But if A and B are conspecific, then C is the sister to
> the species A+B, so A x C is not a hybrid. Following this method, one could
> reduce much of the Orchidaceae to synonymy.
>
> ----------------------------------------------------------------
> Curtis Clark         http://www.intranet.csupomona.edu/~jcclark/
> Biological Sciences Department             Voice: (909) 869-4062
> California State Polytechnic University      FAX: (909) 869-4078
> Pomona CA 91768-4032  USA                  jcclark at csupomona.edu



--
Don E. McAllister             /& Canadian Centre for Biodiversity
Ocean Voice International          /Canadian Museum of Nature
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