Phylocode, Cladistics and Eclecticism ...

[Thomas DiBenedetto]

-----Original Message-----
S. Ingrisch wrote:
>According to the definition of a "cladist" speciation always gives rise
>to two new taxa even if one of the daughter taxa is genetically
>completely identic with the parent taxon.

Igrisch is close enough to the truth to be dangerous. Speciation does not
give rise to two new taxa. Humans recognize and name taxa. Taxon recognition
is a human enterprise that attempts to conceptualize natural phenomena.
Cladists recognize taxa on the basis of the relationahips of common descent
between lineage branches that are isolated from eachother. After a
speciation event the two resulting isolated lineage branches share an
exclusive relationship of common descent with eachother. This is the
sister-group relationship. In addition, each of the two lineage branches are
(in the exact same sense) parts of the original (pre-speciation) unbranched
lineage.

From: Thomas Lammers
They may both be "right" within the context of their definitions, but by
any objective standard, the former is a very very foolish definition.  The
act of speciation does not alter the original species in any demonstrable
fashion.
************
But it does alter it in the one and only fashion that counts in systematics,
Speciation changes the RELATIONSHIPS of lineage branches, and that is the
basis on which we construct phylogenetic classifications.
****
Lammers:
The cladistic insistence
that it IS something different  is merely a legalistic fiction required to
hold up the cladistic house of cards.  I say it again: The Emperor Has No
Clothes!
*******
With all due respect Thomas, I sense that you do not understand what
phylogenetic systematics is all about. We do not classify on the basis of
characters, we classify on the basis of relationships. Characters are
evidence of relationship, so we are dependent on them - unless we have
independent knowledge of the true relationships. In these theoretical
examples that we often discuss, we do have the true relationships laid out
as premises of the discussion. In the real world we may not be able to
discern the true relationships until the "post-speciation larger unit"
develops an apomorphy by which it can be recognized as the sister-group to
the peripheral isolate. Nonetheless, if we are told what has happened, then
the principles to be applied are clear.
****
Lammers:
Principles & methodology have become more important than what really
happened.  In my book, that constitutes Bad Science.
*******
I find this a strange distinction to make. I think that a careful
examination of principles and methodology would do everyone a lot of good.
You seem to claim that because one descendant has not developed an
apomorphy, that the new set of relationships somehow does not really exist.
And this leads you to recognize one descendant-group as part of the
ancestral taxon, and the other descendant-group (the peripheral isolate) as
not part of the ancestral taxon, even though the relationships that the two
descendants have with the ancestral group are exactly the same. You do this
on the basis of characters, while ignoring the real criterion, which is
relationship. Perhaps you simply do not accept that relationships should be
the criterion of classification. If that is the case, fine - you are
certainly entitled to peruse your own principles and methodology. But i do
wish you would make the effort to understand the principles and
methodologies of cladistics before you scornfully dismiss them.

Tom DiBenedetto