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Extinctions (was Re: Paradoxically temporal)

At 10:01 AM 7/23/98 -0600, Chris Brochu wrote:
>>Well, the bottom line is:  Do we have *any* data that indicates what species
>>concept is correct??
>I'm not sure it's a matter of throwing data at them.  Part of the reason
>there's controversy at all is that we have data.
>As for my own approach, I was impressed by something Dave Hillis once said
>in a seminar - we have three concepts in general use (biological - a
>species is a reproductively isolated population; evolutionary - a species
>is a cohesive lineage with its own historical fate; phylogenetic - a
>species is the smallest diagnosable unit in a phylogenetic analysis), we
>can see them all as part of the same thing.  One describes what a species
>is, one describes how we recognize it, and the third describes one way a
>species becomes a species.

Well said!

It is similar to the situation with extinctions: a taxonomist might define
"extinction" as the disappearance of the last member of a species or clade;
a geneticist might define it as the end to flow of a particular genome; and
an ecologist as the time when species range goes to zero.  These are all
equally valid definitions, and all point to pretty much the same event, but
are different ways of looking at it.

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