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Am I a Cladist?

Joe Felsenstein joe at evolution.genetics.washington.edu
Tue Feb 2 16:01:21 EST 1999

In article <795cg5$rou at net.bio.net>,
James McInerney, Zoology <jamm at nhm.ac.uk> wrote:
>Perhaps you can help me.  Following a recent lively discussion at the 
>Natural History Museum in London, I came to the conclusion that I might 
>be a cladist.  

>What are the origins of the word cladist and can I use it in my .sig file?

If I am not mistaken, Ernst Mayr coined the term "cladistics", in the
belief that it would be an uncomfortable label for his opponents to wear!
"Cladist" derives from that.

Guy Hoelzer and Des Higgins have given informative (and funny) answers
already.  Here is my take:

A cladist could be:

   1. A person who wants to make classifications, ones that contain only
      monophyletic (if you're Mayr and Ashlock "holophyletic") groups.
      The most extreme cladist (in this sense) I ever encountered was,
      believe it or not, Charles Sibley, who was adamant that only
      monophyletic groups were tolerable.

   2. A person who makes groups by synapomorphies only.

      In this meaning, Sibley was not a cladist as he used distance methods.

   3. A person who makes phylogenies using only parsimony.

      Actually this may be different from 2, depending on what 2 really
      means.  For example it is easy to make up a dataset that has enough
      homoplasy that the most parsimonious tree has no character that is
      unique and unreversed on it.  Is it then acceptable to the cladist of
      definition 2?  You'll have to ask one of them ...

   4. A person who is interested in making phylogenies.

      This sense was used by Sokal and Sneath when discussing "numerical
      cladistics", the use of algorithms to infer phylogenies.  It is not
      a widely-accepted useage as it would brand many evolutionary
      systematists as cladists and thus conflict too much with definition 1.

   5. A person who is a fully paid-up member of the Willi Hennig Society
      and accepts most of what is said from its podiums.

      Usually used with the adjective "raving".  The second part of the
      definition excludes Norman Platnick and Gareth Nelson, who have lately
      been cast into the outer darkness.

   6. A person in systematics or molecular evolution who uses methods
      newer than the 1954 textbook I used in college.

      This is the popular science press definition.  It goes along with
      statements that there is some new, mysterious, and powerful method
      called "cladistics" that allows us to discern the true tree.

My own preference is for definition #1, as #2 and #3 give the (wrong)
impression that there is something fundamentally lacking in phylogenies
inferred by other means, so that they are not really phylogenies.
If we could use "cladistics" and "cladist" to denote a philosophy of
classification (or its adherent), I think we would all be happier in the
long run.  But many self-defined cladists oppose that definition and want
the method for inferring phylogenies to count.  By definition #1, no matter
what method you prefer for inferring phylogenies, as long as you are
uninterested in making classifications, you are not a cladist (or a
pheneticist, or an evolutionary systematist).

One who does not consider himself a cladist,

Joe Felsenstein         joe at genetics.washington.edu
 Dept. of Genetics, Univ. of Washington, Box 357360, Seattle, WA 98195-7360 USA

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