Phylocode, Cladistics and Eclecticism ...

Fri Mar 15 09:27:32 CST 2002

-----Original Message-----
From: Byron J. Adams [mailto:bjadams at UFL.EDU]
>I think much of the confusion arises when we
>conflate epistemology (HOW we delimit lineages) with ontology (WHAT 
>lineages are, i.e., their reality independent of human observation).

Yes, definitely. Let's hypothesize a "stem lineage", i.e. a population that does not change itself but is budding-off succesively several peripheral isolates each of them with an autapomorphy. If we will apply a cladistic analysis on the result of such process, we will gain simply a polytomy.
Hence, from the cladistic point of view it has a little sense even to speak about the "fate of lineage". If the lineage is unchanged, then it will appear as only one terminal unit in the analysis - despite the number of populations/samples analyzed; if the lineage is changed then it will be placed according its synapomorphy set. What is classified are the terminal units (which can of course represent also fossil samples) and their groups, not the internal nodes of the cladogram. Hence, the "cladogram-species holophyly" resulting from the analysis can be well compatible with "natural-population paraphyly" as hypothesized for real phylogeny course. Cladistic analysis is by definition unable to reconstruct such "real-paraphyly" processes.
Best!
Zdenek Skala