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Re: Princeton Field Guide
On Fri, Oct 22, 2010 at 12:56 PM, <email@example.com> wrote:
> "Phylogenetic nomenclature, on the other hand, assumes evolution and uses
> tree-thinking; this makes everything easier."
> Problem is, it assumes (or at least works most conveniently with) a
> branching-tree model of evolution (cladogenesis); it has issues with
> anagenesis and reticulate evolution.
Not really. Phylogenetic nomenclature requires phylogeny to be modeled
as a directed, acyclic graph, where the nodes (vertices) represent
taxonomic units and the arcs (edges) represent immediate descent.
Anagenesis can be modeled as such (as a series of nodes with one
incoming arc and one outgoing arc apiece), as can reticulate evolution
(nodes with multiple incoming arcs).
It is true that there are difficulties sometimes in determining what
constitutes a taxonomic unit and what constitutes descent. But I think
this is more in the realm of phylogenetics than in the realm of
phylogenetic nomenclature. In other words, it's up to the researcher
to determine the phylogenetic context (how fine or coarse the units
are, what counts as descent, which units are descended from which
other units), and only then PN can step in and attach names to nodes.
T. Michael Keesey
Technical Consultant and Developer, Flex Specialist