[CPN] next set of CBM-related proposals

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On Mon, Oct 29, 2012 at 7:56 AM, de Queiroz, Kevin < deQueirozK at si.edu 
> wrote:
> When it comes to the definition of "clade", it's a bit over-simplified to declare that other people are simply wrong.  They would argue that the definition of "clade" is "an ancestral _species_ and all of its descendants". 
I think we could agree with everyone if we defined a "clade" as the
union of a taxonomic unit with all of its descendants* (where a
"taxonomic unit" is a context-dependent element that can be an
organism, a population, a species, or whatever is deemed an
appropriate unit of life in that context/phylogeny -- life is messy,
after all). Adopting this approach everywhere might be a bit of a
radical change, though, and not terribly productive for now.

> Moreover, some of them might also argue that it is useful to distinguish terminologically between groups composed of an ancestor and all of its descendants that conform (more or less) to a nested hierarchical pattern (species, uniparental organisms) and those that do not (biparental organisms). 
Given Note 2.1.3, this seems of fairly limited use: http://www.ohio.edu/phylocode/art1-3.html#note2.1.3 
* Actually, what would really need to be done is to define a "clade"
as the unit of a cladogen and all of its descendants, where a
"cladogen" is either a single taxonomic unit or the union of multiple
units that all share at least one common descendant.

-- 
T. Michael Keesey http://tmkeesey.net/ 

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