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

[David Marjanovic]

Kevin de Queiroz wrote:

> It counts as two lineage  segments: one from the basal node to A; the
 > other from the basal node to E.

So, if it's branched, it's not a single lineage? Just trying to make 
sure I understand the concept.

> On the contrary, disagreements  about phylogenetic hypotheses are
 > often very similar to disagreements about species circumscriptions in
 > terms of their scientific (or unscientific) bases. Thus, just as
 > different datasets may support different topologies, different
 > datasets may support different inferences about species boundaries.

That is true given the same species concept. It's trivially true given 
different species concepts.

> Moreover, just as different  species circumscriptions may result from
 > people adopting different species criteria (e.g., intrinsic
 > reproductive isolation versus fixed character state differences),
 > different phylogenetic hypotheses may result from people adopting
 > different optimality criteria (e.g, parsimony versus likelihood).

In the latter case, however, scientific arguments can (at least) often 
be made that, given the conditions of the case, one method is less 
error-prone than the others in recovering the true phylogeny 
(reticulated as it may be). In the case of species concepts, there is 
nothing comparable to the true phylogeny; different species concepts 
aren't different approaches to describing true species*, they describe 
different kinds of entities that have nothing in common other than the 
_word_ "species".

* Even though the inventors of many species concepts seem to have 
believed that that's what they were doing.

Mike Keesey wrote:

> A phylogenetic hypothesis  cannot even be formulated until the
 > relevant life forms are grouped into taxonomic units (whether those
 > units are individuals, populations, species, or something else). Only
 > then can the units be related to each other in terms of descent,
 > creating a phylogenetic hypothesis. So the unit taxonomy is an
 > essential part of the hypothesis.
 >
 > I used to argue that the only type of unit should be the individual,
 > since it's objective, but a discussion with a lichenologist
 > disabused me of that notion. There's no simple, objective way to
 > mandate the composition of any type of taxonomic unit, be it species
 > or individual. The Code avoids this problem by recognizing that it is
 > a taxonomic matter, not a nomenclatural one.

I think we have an easy way out: as least as far as specifiers are 
concerned, we can use specimens as opposed to individuals. That leaves 
the decision to the curators. :-)