Darwin (was: Phylogenetic evidence)

[Ken Kinman]

Barry,
      I detect no hint of any complaint (about ranks) in Darwin's statement.
  Could this be wishful thinking on your part?  :-)
      Seems to me he is making a straightforward observation about how to
"express" differential anagenesis (different degrees of modification) in a
classification.  And this can be just as true for molecular data as it is
for morphological data.
     It's perfectly natural to give two sister groups different rank based
on  different degree of divergence.  The therapsid Family Tritheledontidae
went extinct early on and therefore had no chance to diverge nearly as far
as its sister group Class Mammalia.  Likewise a genus can be a sister group
to a whole family or even an order.  I see no problem with this as long as
you explicitly show such sister group relationships (as I do with my exgroup
markers).
     Seems to me Darwin is just acknowledging that this is the way it was
done and there would have been no need to "endorse" it.  And this is still
done, in spite of strict cladism's efforts to demonize and snuff out
paraphyly completely.  If you really think Darwin was a proponent of
unranked taxonomy, I would think you could find a more direct statement in
his many writings.  I don't recall any indication that he would have
preferred unranked classifications, nor do I have any reason to believe he
would prefer strict cladism if he were alive today.
         ------ Cheers,  Ken
***************************************
>From: Barry Roth <barry_roth at YAHOO.COM>
>Reply-To: Barry Roth <barry_roth at YAHOO.COM>
>To: TAXACOM at USOBI.ORG
>Subject: Re: Phylogenetic evidence
>Date: Wed, 10 Jul 2002 09:03:14 -0700
>
>Ken,
>They say the Devil can cite scripture for his purposes.  Let's see.  In
>your linked message you quote Darwin thus:
>
>       "but that the amount of difference in the several branches or
>groups,
>though allied in the same degree in blood to their common progenitor, may
>differ greatly, being due to the different degrees of modification which
>they have undergone; and this is expressed by the forms being ranked under
>different genera, families, sections, or orders."  (Origins of Species,
>Chapter 13)
>
>
>I read this as Darwin's insight that morphology is an imprecise guide to
>degree of consanguinity and his recognition that the standard, ranked
>classification is based on "magnitude of difference" in morphology, not
>phylogeny.  He states that this is the case; he doesn't necessarily endorse
>it.  In fact, his statement is a complaint about the problem.
>
>
>
>I therefore claim Darwin as an early proponent of unranked taxonomy.
>
>
>BR (adjusting his horns)
>
>
>  Ken Kinman wrote:Barry,
>I wholeheartedly agree with Darwin on this, but this is only a partial
>quote, and omits an extremely important qualifier (which strict cladists
>often prefer to ignore).
>See my post on this subject in January 2001 at the DML (dinosaur
>mailing list). Here's the link:
>
>http://www.cmnh.org/dinoarch/2001Jan/msg00328.html
>
>
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