Apology, was Re: genetic vs morphological trace of phylogeny

Richard Jensen rjensen at SAINTMARYS.EDU
Thu Apr 15 12:17:41 CDT 2004

John Grehan wrote:

> So while its true I am not as familiar with the ins and outs of molecular
> approaches and so perhaps I should be saying nothing, it is also evident
> from the literature that there are problems raised by molecular
> systematists that give credence to the proposition that a molecular
> phylogeny is not inherently true, no matter how self-consistent, and it is
> also evident that at least some cladists also question whether DNA sequence
> and related approaches are really 'cladistc' or just phenetics dressed up
> in cladistic terminology and analyzed using algorithms that are also
> applied to cladistic characters in morphology.

Let's face it, no non-trivial phylogeny is "inherently true."  All phylogenies must
be viewed as hypotheses and are open to question.  And, to reiterate a point I made
in an earlier post, all data sets are, in a sense, phenetic.  That is, the
recognition of characters (attributes) that can be used for inferring relationships
is the same whether one intends to perform a UPGMA analysis, an NJ analysis, or any
of the many options for parsimony analysis.  The difference arises when one
considers the goal of the analysis. That requires decisions about models of
character evolution, etc.



> --

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

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