Phylocode, Cladistics and Eclecticism ...

Thomas DiBenedetto tdib at OCEANCONSERVANCY.ORG
Thu Mar 14 12:26:14 CST 2002


-----Original Message-----
From: Ken Kinman
     Where American cladism (in particular) got off track was that they took
Hennig's sister group "convention" and turned it into a "definition".
...we now have a whole generation of biologists having been taught
that sister groups are REAL, rather than a methodological convention.  From
that incorrect premise, they can argue that paraphyletic taxa are unreal,
unscientific, and are mistakes that must be corrected (destroyed).
********
I do not think that anyone questions the fact that after a speciation event,
there are (at least) two isolated lineage branches. These branches share
with each other, and with no other taxon, a most recent common ancestor (the
pre-speciation lineage). This is the sister-group relationship. It is beyond
my comprehension how Kinman, or anyone else, can pretend that this
relationship is not real.
**********
Kinman:
     If you try to argue from the perspective that paraphyletic species are
real, they will just argue either (1) that species are arbitrary and thus
not real; or (2) species and higher taxa are just "apples and oranges" and
can't be compared.
******
Niether of these arguments are the ones that are consistently raised against
your postion. Wouldn't it be wonderful if we could all choose the arguments
raised against us?!
***
Kinman:
     To me, clades are real (although their boundaries are unavoidably fuzzy
and arbitrary).  Sister clades are NOT real, but they are a useful
convention within the context of cladistic analysis.  When this distinction
(clades vs. sister clades) is brought to the attention of today's students
who were taught by a strict cladist, many of them feel they have been
misled.
*********
Well, I am as eager as the next person to be shown how I have been misled.
Could you please explain to us this distinction that you see - that clades
are real, but the notion that a real clade might share a "most recent common
ancestor" with another real clade is not real?

Tom DiBenedetto




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