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Re: Clade II



From: "Jonathan R. Wagner" <znc14@ttacs1.ttu.edu>
 > >    To emphasize other evolutionary phenomena besides common descent. 
 >         I've said it before, I'll say it again, why would you wish to
 > obscure the most confusing aspect of evolution behind those aspects
 > which are more readily discernable?

I do not know what Jeff woudl says, but here is my take:

To make the classification more useful in ordniary discourse.
The most useful classification for most purposes is one in which
allows quick classification of a new specimen in the field without
needing extensive analysis.

As an example, I have found I can recognise members of most families
of flowering plants at a single glance. This makes the flowering plant
family a *very* useful category, since I can do a quick field survey at
that level without much trouble.

 >  If any two-year old can tell the difference
 > between a bird and a non-avain dinosaur,

*Because* any two-year old can tell the difference.  This means that
the difference is a *conceptually* natural one.  It fits with the way
people think about things.

 > why should we include this at the
 > risk of obscuring their theorised relationships?

No.  But the relationships can be better expressed in a tree diagram.
So why make them harder to understand by recasting them in the less
intuitive (for *that* purpose) form of a classification?  Leave the
relationships expressed in their most natural form - a tree diagram.
Then use the classification to *add* something more to the data,
beyond what can be easily expressed in a tree diagram.

 >   The modifications are inexorably bound to the decent, yes.  However,
 > which of these concepts is the more specific?

They are each, in their own way, about equally specific - just
in different ways.

 >    I will paraphrase and add to the statements made by another member
 > of the list who chose not to post his views.  "Evolutionary taxonomists"
 > admit that phylogeny should have a place in taxonomy.  And yet they do what
 > could be described as a "half-keystered" job of actually doing this, by
 > obscuring the phylogeny with character state data.

Similarly, it has been said that phylogenetic systematists, in the name
of basing taxonomy solely on evolution, have chosen to ignore half of
the process of evolution: namely anagenetic change.

swf@elsegundoca.ncr.com         sarima@ix.netcom.com

The peace of God be with you.