Molecular taxonomy, etc.

Richard Jensen rjensen at SAINTMARYS.EDU
Thu Jul 21 12:40:12 CDT 2005

John Grehan wrote:

> And have
> > you never grasped that most cladistic algorithms do not - and cannot -
> > consider polarities. Without further input they provide an UNROOTED
> tree.
> Agreed. Although I see nothing cladistic about that. What is the
> critiorn by which you see unrooted trees as being cladistic?

If you do not understand that a most parsimonious network is cladistic, then
it is clear that you are patently misinformed or that you just don't
understand cladistic methodology.  You can examine the network and identify
synapomorphies, and that makes it cladistic! If you examine the early papers
on cladistic methodology (e.g., Farris, 1970: Syst. Zoo. 19: 83-92), you
will note that the fundamental algorithm employed is one for constructing
networks, not trees.  A tree is nothing more than a *directed network* and,
as pointed out repeatedly, adding direction does not change topology.  I
suggest you carefully read, or reread, the Meacham (1984) and Nixon &
Carpenter (1993) papers that were noted earlier.

Dick J.
Richard J. Jensen              | tel: 574-284-4674
Department of Biology      | fax: 574-284-4716
Saint Mary's College         | e-mail: rjensen at
Notre Dame, IN 46556    |

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