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Date: Mon, 25 Feb 2002 15:25:16 -0500 (EST)
From: "T. Mike Keesey" <tmk@dinosauricon.com>
To: "Jonathan R. Wagner" <jonathan.r.wagner@mail.utexas.edu>
Cc: -PhyloCode Mailing List- <PhyloCode@ouvaxa.cats.ohiou.edu>
Subject: Re: interesting style of definition
On Mon, 25 Feb 2002, Jonathan R. Wagner wrote:
> I think C is pretty unequivocally "nearer in descent" to B, in that
> their lineages (the trail of ancestry and descent leading from each back
> through time) share a longer common segment than either does with A. Or, to
> put it another way, their lineages diverged more recently than their common
> lineage did with C. Or an even better way: they share a community of descent
> independent of C. They share community of descent independent of C, and in
> turn this group will have a similar relationship with other taxa, and so on,
> proceeding by incrementally quantized degrees of propinquity of descent.
>
> The diagram above represents a nonunique solution: there is no objective
> measure of anagenetic distance, at least for (phenotypic) morphology. There
> may be for genetic distance, I just don't know. By my understanding, this is
> why phenetics and gradistics both fail to provide an objective method of
> classifying organisms... the "distance" factors are ultimately
> unreproduceable (and there are philosophical reasons why this should be so).
> Hence, propinquity of descent is the only (theoretically) objective means of
> delineating named groups of species (or organisms, if you don't care for
> that class of entity).
Okay, I understand the issue there -- I'm really just wondering if
everyone uses the term "related" in the cladistic sense (regardless of
whether they should).
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