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Re: Evolution programs (was: Reevolving bones)

At 09:36 AM 5/8/97 -0500, Rob Meyerson wrote:

>One further question:  Does cladistics take geography into account?  I'm
not talking about terrain or climate, but where on the Earth each of the
genera is found?  Could a cladistic analysis claim that animals on separate
continents are more closely related than those on the same continent (and is
this feasable)?

It can claim that, and it is feasable, especially given the vagility of
different organism groups (especially over geologic time).

For some recent examples: Bison bison and Bison bonasus (the bison and the
wissent, respecively) are more closely related to each other on morphologic
grounds (and, I would imagine, molecular grounds, although I don't know if
people have looked at wissent genes), even though there are plenty of other
bovines in the Old World which are geographically closer to the wissent than
to the bison.

New World opposums and Aussie possums are more closely related to each other
than opposums are to racoons (for example), or possums are to echidnas, even
though the former pair share the same geographical realm, as do the latter pair.

There is a whole realm of study of cladistic methodology in biogeography,
primarily concerned with modern forms but also employed with fossil taxa.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661