[Taxacom] burn out (was: classification of Class Rosopsida)

Mario Blanco mblanco at flmnh.ufl.edu
Sun Apr 12 17:33:31 CDT 2009

Richard Zander wrote (in brackets):

[ The reason some of us insist on paraphyletic taxa is because evolution,
if defined as descent with modification, is described only by
paraphyletic-autophyletic series, where the paraphyletic taxon is the
descendee (ancestor), and the autophyletic taxon is the descender. ]

   Not true. Evolution does not require a classification to be 
described. If you meant "represented" instead of "described", then your 
statement is also erroneous. Evolutionary history can be represented by 
a cladogram, and can be summarized by a series of monophyletic clades 
nested in other (monophyletic) clades. You can circumscribe every clade 
so they are all monophyletic.

[ In a phylogenetic cladogram with paraphyly eliminated, we know what the
descender is, it is the exemplar, but we don't know what the descendee
is, it is only a node, without diagnosis or any real biological
attribute. ]

   A cladogram by itself does not have paraphyly or monophyly. Those are 
attributes of classifications. If you meant to say "phylogenetic 
classification" instead of cladogram, then your are implying that in a 
paraphyletic classification you know the "descendee" (I guess you mean 
ancestor), which you do not know by just looking at the names of taxa in 
either type of classification. Just by looking at a group of names of 
families in a paraphyletic classification, you cannot know if one of 
them originated from another. In a phylogenetic classification, at least 
it is safe to assume that none of them originated from another taxon in 
the same rank.

[ The central stem of a phylogenetic lineage is a series of
nothings. ]

   It is a series of hypothesized ancestors. Same as in a paraphyletic 
classification. Again, you are confusing cladograms with classifications.

[ ONLY demonstration of descent with modification of taxa will demonstrate
evolution. This may be done in several ways, but demonstration of
paraphyly should be the one way systematists should try to preserve by
not enforcing holophyly in circumscribing taxa. ]

   Again, an explanation of the evolutionary process does not require a 
pre-existing classification. You are stating your preference of 
classification methodology as if it was a fact.

Mario Blanco

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