kingdom protozoa

Charles J. O'Kelly okellyc at megasun.BCH.UMontreal.CA
Tue May 3 08:23:02 EST 1994


In article <01HBSI4BHRS20012MC at AC.DAL.CA>, AROGER at AC.DAL.CA writes:
|> Hi,
|> 
|> Can anyone specifically tell me what they find inaccurate
|> about [Cavalier-Smith's] paper?  Farmer's claim that the paper was based mostly
|> on work by others seems rather silly; is one supposed to classify
|> an entire kingdom of eukaryotes using only characters and data
|> that one has generated onesself?

I am not particularly worried that Cavalier-Smith has set his ideas down on paper. 
Throughout the history of classification, the central ideas have often been those set
down by a single individual.  I am not entirely convinced that classification by
committee is any more effective than classification by individual inspiration.  It
could even be said that TCS is doing no more than his duty as a scientist and (Ph.D.s 
please note) philosopher by making his ideas public.

My principal objections to TCS's work are these.

(1) His schemes, like all others, stand or fall on the assumptions on which they rest.  His
ideas about how eukaryotic cells evolved are explicitly stated.  They are explicitly stated
differently in each paper he writes, but they are explicitly stated.  If one disagrees with
his ideas about eukaryotic cell evolution, then one disagrees with his classification.

Example: TCS, if I read him correctly, assumes that the first mitochondrion had discoidal
cristae, and that other types arose from this first type.  I believe that the three main 
types of mitochondrial cristae arose practically simultaneously, and think I've got a group
of bugs that provide a test case (O'Kelly CJ. 1993. JEM 40:606; I no longer think that the
polyphyletic origin scenario for mitochondria is plausible, although I considered it an
option in the above paper).  The differing hypotheses lead to not inconsiderable differences
in classifications, especially since we would put different groups of bugs at the base
(he, Percolomonas; I, the jakobids).

(2) TCS's classification methodology appears to be related to the "evolutionary taxonomy"
paradigm as recently defended by Ernst Mayr.  He rejects cladism on the grounds that,
ultimately, all taxa are paraphyletic.  I by no means consider myself a "pure cladist", but
nevertheless TCS's wholesale creation of admittedly paraphyletic taxa (the taxon has one
ancestor, but does not include all the descendants of that ancestor) rubs me the wrong way.  
I think we can, and should, do better at identifying the clades before we attempt to name 
higher taxa, and these taxa should be monophyletic (one ancestor and the taxon includes all the
descendants of that ancestor - the Hennigian definition of monophyly) to the greatest
degree possible.

Unfortunately, as another poster has pointed out, the desire of people like me to "get it
right" before publishing does not sit well with folk who have to work with protists today
and need some sort of framework.  By publishing his ideas, TCS provides the appearance of
such a framework.  Perhaps some of us worry that Tom's work may have an unfortunate effect
... "hey Cavalier-Smith has already done protist classification, what do we need more work 
in this field for???"

|> 
|> Andrew Roger
|> aroger at ac.dal.ca

Charley O'Kelly
Mad Protistologist
okellyc at bch.umontreal.ca



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