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

[John Grehan]

"Molecular analysis can let one know when one taxon is in the wrong
cluster and
> point out the right cluster"

Should that be "may let one know"?

John Grehan

> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Richard Zander
> Sent: Monday, April 13, 2009 10:04 AM
> To: Mario Blanco; TAXACOM
> Subject: Re: [Taxacom] burn out (was: classification of Class
Rosopsida)
> 
> Mario:
> You cannot refute the points I am making by making true statements
about
> other things.
> 
> Classification should be based on evolution, most of us agree. My
> central point is that alpha taxonomy has the best grip on
> evolution-generated groupings, and that molecular analysis can
> demonstrate direct evolutionary relationships (paraphyly-autophyly
> series) between such groups as ancestor-descendant relationships (that
> is, involving descent with modification of taxa).
> 
> Classification by holophyly eliminates this information. The "natural"
> taxa are already classified by alpha taxonomists, and are chock full
of
> evolutionary information that molecular analysis can reveal. Molecular
> analysis can let one know when one taxon is in the wrong cluster and
> point out the right cluster but otherwise the classification is
already
> there in the original evaluation by an alpha taxonomist.
> 
> Discovery of paraphyly, "massive homoplasy," and "cryptic" taxa has
been
> misinterpreted. These features are evolutionary information and should
> not be hidden by burying them (in synonymy or splitting into new
names)
> in phylogenetic classifications.
> 
> *****************************
> Richard H. Zander
> Voice: 314-577-0276
> Missouri Botanical Garden
> PO Box 299
> St. Louis, MO 63166-0299 USA
> richard.zander at mobot.org
> Web sites: http://www.mobot.org/plantscience/resbot/
> and http://www.mobot.org/plantscience/bfna/bfnamenu.htm
> Non-post deliveries to:
> Missouri Botanical Garden, 4344 Shaw Blvd., St. Louis, MO 63110
> *****************************
> 
> 
> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu
> [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Mario Blanco
> Sent: Sunday, April 12, 2009 5:34 PM
> To: TAXACOM
> Subject: Re: [Taxacom] burn out (was: classification of Class
Rosopsida)
> 
> 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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