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Date: Tue, 28 Aug 2001 14:33:07 -0500
From: kritosaurus <kritosaurus@netzero.net>
To: "Alastair G. B. Simpson" <simpson@hades.biochem.dal.ca>
Cc: PhyloCode mailing list <phylocode@ouvaxa.cats.ohiou.edu>
Subject: Re: Apomorphy-based definitions
Alastair G. B. Simpson wrote:
> Well, you move the problem to being one of determining when
> one species transforms into the next one: However one would guess that
> there is no perfect way defining that either.
Actually, I would regard species as being self-bounded, and those
boundaries as (necessarily) "fuzzy." This is entirely analogous to
determining the most recent common ancestral organism of two individuals:
the most recent common female ancestor of myself and my sister (at the
organismal level) is our mother, despite the grey area surrounding the point
in space and time where she became an individual distinct from her mother,
and despite the grey area surrounding the point in space and time where we
became distinct from her. Likewise, no one seems to be bothered with the
notion that some cells in my mother's body might share a more recent common
(cellular) ancestor with my sister than with me (although this seems
unlikely to me). That is a question which is best addressed at the cellular
level, and not the organismal level.
To return to your point, I find that looking at clades in terms of
species (as individuals) clears up the point rather nicely. Would it be
possible for you to clarify how ambiguities in the recognition of species at
and around speciation events affect the issue at hand (which, I believe,
involved difficulties in recognizing ancestors)?
Jonathan R. Wagner
9617 Great Hills Trail #1414
Austin, TX 78759
----- Original Message -----
From: Alastair G. B. Simpson <simpson@hades.biochem.dal.ca>
To: Jonathan R. Wagner <jonathan.r.wagner@mail.utexas.edu>
Cc: PhyloCode mailing list <phylocode@ouvaxa.cats.ohiou.edu>
Sent: Monday, August 27, 2001 8:10 AM
Subject: Re: Apomorphy-based definitions
>
> On Sun, 26 Aug 2001, Jonathan R. Wagner wrote:
>
> > Actually, if species are considered to be individuals (a divisive
> > suggestion, I know), than an entire species may be considered to be
> > "ancestral" to another, just as an entire organism is ancestral to
another.
> > If this is held to be the case, the "most recent common ancestor" refers
to
> > a SPECIES, not an organism, and the problem you discuss vanishes.
>
> Well, you move the problem to being one of determining when
> one species transforms into the next one: However one would guess that
> there is no perfect way defining that either.
> (Needless to say, some level of fuzziness will creep into any system
> of taxon definition; Node- Stem- and Apomorphy-based definitions do a
> great job of minimising it!)
>
> Alastair Simpson
>
>