[Taxacom] New synapomorphy for humans and orangutans

Richard Zander Richard.Zander at mobot.org
Wed Jan 6 18:19:42 CST 2010


Yes, of course. You are right, Ken. I meant absent in the sense of it being difficult or impossible to retrieve. And I mean significant paraphyly, since all (most?) new taxa come from paraphyletic ancestral taxa. 
 
_______________________
Richard H. Zander
Missouri Botanical Garden
PO Box 299
St. Louis, MO 63166 U.S.A.
richard.zander at mobot.org
 

________________________________

From: taxacom-bounces at mailman.nhm.ku.edu on behalf of Kenneth Kinman
Sent: Tue 1/5/2010 8:56 PM
To: taxacom at mailman.nhm.ku.edu
Subject: [Taxacom] New synapomorphy for humans and orangutans



Hi Richard,
      I would tend to agree with you that John seems to have fallen into
a common fallacy, and would DEFINITELY agree that failure to take
paraphyly into account has become an even bigger problem.  However, I am
not sure how to interpret your phrase "ancient paraphyly that is now
absent". 
     Is the ancient paraphyly actually absent, or is the problem more
precisely that ancient paraphyly is just extremely difficult to detect,
due to extinction (as well as the failure of strict phylogeneticists to
recognize and address this difficulty)?  I can see where a strictly
phylogenetic approach could unfortuately and prematurely cut off
attempts to explore such paraphyly, but can we really say that such
ancient paraphyly is truly absent?
       ---------Cheers,
                     Ken Kinman                            
**************************************************
Richard Zander wrote:
     Genome changes can't back up much unless, in my opinion, they
demonstrate considerable distance between where a taxon is now placed
and where it ought to go. Like, opps, wrong family. This is because of
extinction. If there is x% paraphyly in a present-day set of exemplars,
then there should be x% at every node to take into account ancient
paraphyly that is now absent. Which significantly reduces bootstrap and
credible values.

The above requires one to accept that one taxon may exist in two or more
molecular lineages. This phenomenon is demonstrated in nearly every
study that has two or more exemplars of the same taxon, yet is
cognitively dissonated.

The orangutan problem is Taxacom's very own instructive puzzle, with
equivocal signs of what the ancestor of man might be like in expressed
traits. Suppose both chimp and gorilla were extinct and unknown from
fossils. Well, the shared ancestor would be taken to be some
intermediate between orang and man. What if there were a dozen chimp and
gorilla-like lineages between man and orangutan? Well, the immediate
ancestor would be something like a chimp or gorilla.

I note that John Grehan has fallen into the "evolutionary relationships
= evolution" fallacy. This is easy to do because of peer pressure.
Relationships are okay, but indirect. We really want to know what the
sequential evolutionary derivation of taxa might be, which is direct. I
think we can infer the latter in many cases, e.g. when a number of
exemplars of the same species bunch together on a cladogram, well the
ancestral taxon is that species. Yet those who insist that relationships
are the end-all of evolutionary analysis will not follow the several
clear lines of investigation that follow this observation, e.g. the
ancestral taxon of an autophyletic taxon is the paraphyletic taxon
generating it.



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