Paraphyly is real
skala at INCOMA.CZ
Wed Jan 16 09:12:31 CST 2002
Tatyana Livshultz wrote:
>>Cladistic classification has been evaluated on the basis of explicit
optimality criteria, information
>>content and predictivity, and found to be superior to phenetic or
eclectic classification. I give the reference
Don Colless wrote:
>I suggest folk read the Farris paper carefully, making sure that they
fully understand what it's all about,
>and that they agree that the arguments follow from the premises -
before they accept anything about
>"information content". The latter is a most slippery concept, and
susceptible to all sorts of manipulation
>to serve a prejudged result.
I strongly suspect that cladistics and eclecticism simply optimize their
monophyly concepts along different criteria/by different measures - this
was my motivation to write about them. If so, it would be no surprise
that there is little agreement about which one is better. It would be
probably useful do reveal explicitly which are these criteria. Maybe it
concept: holophyly ("strict monophyly")
criterion: taxa should represent the branching order of the phylogeny as
much as possible
underlying assumption: branching is the basic phylogenetic process, so
taxa should represent it
concept: holophyly+paraphyly allowed ("loose monophyly")
criterion: taxa should represent the overall similarity generated by
phylogeny as much as possible
underlying assumption: character change is the basic phylogenetic
process, however only similarities due to common descent are "the same
thing" - hence the common descent
This could, for example, easily resolve the differing meanings about
"paraphyletic species" (see this thread earlier).
I however, doubt if one can decide which of these two concepts is more
in line with a "true phylogenetic thinking" - for me, both are.
[Nota bene: the cladistic concept is still a bit loaded by "anagenetic"
thinking: it should elaborate purely topologic criteria to where to
place the taxa boundaries (now, I guess, the most significant clusters
of synapomorphies are used).]
skala at incoma.cz
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