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From: lmc@denelcor.UUCP (Lyle McElhaney)
Newsgroups: net.origins
Subject: Re: On the Rio Grande
Message-ID: <739@denelcor.UUCP>
Date: Fri, 3-May-85 01:42:56 EDT
Article-I.D.: denelcor.739
Posted: Fri May  3 01:42:56 1985
Date-Received: Mon, 6-May-85 01:14:40 EDT
References: <251@cmu-cs-edu1.ARPA>
Organization: Denelcor, Aurora, Colorado
Lines: 43

> > >>      When it comes right down to it, species are  the  only  real
> > >> All higher categories are based on the sub-
> > >> jective judgment of specialists.
> > >> One man's "genus" is another  man's  "fami-
> > >> ly".
> > 
> > > There is nothing to justifiy your claim that species are the only
> > > "real entities".  In addition, you would not classify a bacteria
> > > with an elephant.  The classification hierarchy is not whimsical,
> > > as you so suggest.
> > 
> > First sentence is true.  The meaning of species has never been agreed
> > on.  But whimsey is not suggested.  Lief simply points out a fact of
> > taxonomic controversy.  Are you suggesting that there *is* a
> > classification scheme that everyone can agree on?
> 
> Certainly not.  But there is a large degree of agreement in all levels
> of subdivisions.  There are, of course, the "borderline" cases, but
> you simply do not see biologists arguing over the proper kingdom of
> gophers.

Ah, but there is an agreed upon meaning of species. To quote the
paleontologist Roger J. Cuffy:

"Low-rank taxa - the many species known to us - have a real existance
in nature, in that they consist of populations or morphologically similar,
actually and potentially interbreeding individuals which live during a
continuous segment of geologic time.

On the other hand, high-rank taxa - those above species rank, from genera
up through phyla - do not have a real existance in nature in quite the same
sense that species do. Instead, higher taxa of various ranks are simply
the scientists' mental abstractions by which the many species comprising
the organic world are grouped according to the various degrees of over-all
morphological similarity displayed.

The practice has developed among modern taxonomists that higher rank
classifications, which are initially based upon observable degrees of
morphologic similarity between species, also should reflect evolutionary
ancestor-descendent relationships among those species as much as possible."
-- 
Lyle McElhaney
{hao, stcvax, brl-bmd, nbires, csu-cs} !denelcor!lmc