Phylocode, Cladistics and Eclecticism ...
tdib at OCEANCONSERVANCY.ORG
Thu Mar 14 12:26:14 CST 2002
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.
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?!
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
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?
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