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Re: Species concepts



> Nick, you must have missed my subsequent post. I contend that lions and tigers
> (and here I'll include the other big cats) are still in the process of
> diverging from their common ancestor. I therefore consider them all to be not
> the same species, nor yet *entirely* distinct species. They're transitional.

This is a reasonable thought (the transitional concept), but beware that
you're looking at a huge number of transitional species if you apply this
concept widely.  Plants, of course, would be one.  Amongst vertebrates,
snakes pose quite a problem.  They mate and produce fertile offspring
between recognized genera.

The BSC, and in fact many species concepts, were probably produced with
mammals or birds in mind, and really do not apply to a wide range of other
organisms.

The point of utility has been made on this thread, and I think it's rather
important.  The phylogenetic species concept, for example, is often shunned
because it creates so many new species (relative to BSC).  Ultimately, the
'species' is just a human construct anyway (also been mentioned), so we
should not expect any one definition to fit, nor should we use definitions
that are very difficult to utilize.

After all, morphology, recognition, hybrid incapability, gene flow, etc. are
all continuous characters, so in the end we're always trying to create
discrete entities out of continuous traits.  Which means, in short, that
different species concepts are probably going to have to be applied to
different groups.  It also means we should probably not beat ourselves over
the heads too much trying to figure out what a species distinctly is.  A
species isn't distinctly anything, as it really doesn't exist.  Clades are
real, but families and genera are as arbitrary as species...

--Mike Habib
habib@virginia.edu