Cladistics and Eclecticism

SKÁLA Zdenek skala at INCOMA.CZ
Thu Feb 7 17:03:09 CST 2002

Z Skala:
>>For those that use solely the topology of phylogenetic
>>relationships paraphyletic species obviously cannot exist. For those that
>>want to include character information in the systematics paraphyletic
>>species do exist well.

T DiBenedetto:
>... Cladistics uses character information. ... What else is there to
>cladistics except the extraction of pattern from the character information?
>...The purposeful recognition of a paraphyletic group means that one
>disresepcts the evidence from characters, ...

Yes, characters are used for cladogram construction. Quite surprisingly to me, you are considering them as irrelevant immediately after the cladogram is ready. What we really do in cladogram construction is summarizing the "amount of character change" (i.e. the largest clusters of mutually compatible synapomorphies) to construct/recognize "real" clades. Eclecticists simply take this operation seriously and use these clusters of synapomorphies also for the splitting of the cladogram. Yes, as a side effect of this operation, paraphyletic taxa can appear. I do not see, however, any "disrespect of the character evidence" in this.

Z Skala:
>>(2) On the other side, cladists would like to have also a
>>character-informative taxa; topology itself, however, does not provide
>>criteria of how to split a cladogram into a set of taxa.
T DiBenedetto:
>Of course it does. The cladogram IS the organization of taxa.

Read better. I have written that topology does not provide criteria for cladogram *split*; if the taxa can be *arranged according to cladogram* is another story. It was YOU who insisted that the splitting of cladogram is an arbitrary process.

>I completely disagree with your notion that monophyletic and paraphyletic
>taxa are somehow equally arbitrary.

Well, mono(holo)phyletic taxa need not be arbitrary (in the sense of cladogram split) if you will recognize all clades as taxa. With this method (which you apparently acknowledge as possible) even most of cladists will disagree, IMO. Otherwise, there is still the same amount of arbitrariness in the splitting of the cladogram into taxa - be it holophyletic or paraphyletic.

>Monophyly is the recognition of real
>lineage branches... etc. etc. etc.
>..., then you are introducing non-natural criterea to your

Tautology, as indicated already and also by others in this thread.

Zdenek Skala

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