[CPN] Fwd: PLEASE VOTE on CBM-related proposals

[David Marjanovic]

> The problem illustrated by  David's fish example is a consequence of
 > our having broadened the PhyloCode's operational definition of the
 > species category to accommodate those who do not accept the idea that
 > a species is a population lineage segment.

Really? Here's my example again:

--+--A
   `--+--B
      `--+--C
        `--+--D
          `--E

A and E can interbreed with each other, but all other combinations don't 
work.

All nodes should be considered parts of the species A + E; they were all 
able to interbreed. The species is (multiply) paraphyletic, not 
polyphyletic. Does that not count as a lineage segment?

> I am not suggesting that we  revisit that decision, which I personally
 > support, but if we retain a broad operational definition of "species"
 > in the code, we may simply have to accept that differences in species
 > concepts or hypotheses of species boundaries will result in
 > occasional changes in the application of the names of low-level
 > clades whose contents coincide with or overlap the membership of
 > those species. As Kevin pointed out to me in our discussions of this
 > problem over the past couple of weeks, variability in the application
 > of clade names due to differing conceptualizations of the species
 > used as specifiers is analogous to variability in the application of
 > clade names due to differing phylogenetic hypotheses.

I disagree. Disagreements about phylogenetic hypotheses are (hopefully) 
scientific disagreements -- different datasets supporting different 
topologies, that kind of thing. Disagreement about which species concept 
should be called "species" are purely semantic. That's, as I said, 
_precisely_ what the PhyloCode is supposed to stop. One of the most 
important ideas behind phylogenetic nomenclature is to turn the question 
"does organism X belong to taxon Y?" into a scientific hypothesis.

Consequently, I still think species shouldn't be used as specifiers. 
Phylogenetic nomenclature is about clades; mixing species in causes trouble.