RE: Species [arbitrary to a degree]

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> ELurio@aol.com
>
> The difinition of a species has always been any group of
> organisms who can
> produce
> fertile decendants.

Not true, actually.  The definition ELurio gives was developed in the
mid-20th Century, centuries after Linnaeus and company first applied the
term "species" to that "kind" of organism most people agree are species.

However, the definition ELurio gives is a close approximation of the
Biological Species Concept (BSC), which did indeed dominate 20th Century
thinking on the nature of species.

A check at a good science library will turn up a few (dozen) books and a few
(hundred) papers on "the species problem" or "the species concept".  Just to
name a few simple problems with the BSC: under the definition as ELurio
gives it, lions and tigers are members of the same species (ligers are
cross-fertile with tigers, at least), as are grizzlies and polar bears
(which produce fertile 'golden bear' offspring, as was discovered by the
National Zoo after a romantic liason that the workers were wise not to try
and interrupt...).

So the BSC is a good first approximation, but it is ONLY an approximation.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796