Ernst Mayr defined species as: “A group of actually or potentially
interbreeding natural populations reproductively isolated from other such
populations.”  Note he does not say they CANNOT interbreed and makes no
mention of fertility or infertility of hybrids as a species test.  Mayer's
definition is one of the cleanest for species, but does run into problems
with some bacteria that interbreed yet remain genetically distinct.  Throw
plants into the equation and things can really get confusing.

Tom E.

-----Original Message-----
From: Conchologists List [mailto:[log in to unmask]]On Behalf Of
Monfils, Paul
Sent: Friday, July 08, 2005 9:51 AM
To: [log in to unmask]
Subject: Re: DNA tests on molluscs


Fred,

If interbreeding is the sole (or principle) criterion for speciation, where
do hybrids come from?  Hybrids should be impossible if species, by
definition, cannot interbreed.  Are the domestic dog, the wolf and the
coyote conspecific because they sometimes interbreed?

Paul M.

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