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Am I a Cladist?

fatherdes at hotmail.com fatherdes at hotmail.com
Tue Feb 2 11:43:22 EST 1999


In article <795cg5$rou at net.bio.net>,
  "James McInerney, Zoology" <jamm at nhm.ac.uk> wrote:
> Dear all,
>
> 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.  However, my confusion arises because of the fact that
> possession of this term has almost exclusively been reserved for
> systematists who use the principles of parsimonious reconstruction of
> phylogenies, to the exclusion of all other methods.
>
> Now, although I use distance matrix methods (LogDet included) and the
> various likelihood methods for reconstructing phylogenetic relationships
> (along with quartet puzzling, maximum parsimony, spectral analysis,
> split decomposition), I still think that my prime motivation is to discover
> clades of organisms/sequences.  Therefore I am a cladist.
>
> I am also interested in temporal data...when things happened and if this
> correlates with any other data such as seismic activity or whatever.
>
> What are the origins of the word cladist and can I use it in my .sig file?
>
> kindest regards,
>
> James
>

If you are not directly interested in taxonomy/systematics as such and if you
are simply trying to derive/estimate/figure out phylogenies then the term is
probably not applicable in a strict sense.  There is still considerable
overlap and confusion and it depends a lot on what type of hat you wear.

If you wear a cladist hat then you will use parsimony even in situations
where it is probably not ideal because you have a profound
psychological/religious/scientific aversion to anything else except maximum
likelihood which, if you are like me, you would not fully understand anyway,
but you might be a bit intimidated by it and feel you should be doing more of
it. You would rather count copepods than use distance methods.	This would
apply even if you were trying to estimate a phylogeny except you would not
use that word (estimate).  You would probably, also, prefer not to bootstrap
anything, just in case that lead you down the slippery slope of probabilities
and all that non cladistic stuff.  You would probably also not like to use
any multiple alignment methods that used any kind of distance tree along the
way.  Indeed you would probably wish there were no molecular data in the
first place.

If, on the other hand, you wore a rabid anti-cladist hat (and you can be one
even if you are not a taxonomist; an anti-cladist that is, not a hat) there
would be entire stretches of the Phylip package which would be simply unknown
to you.  Anything parsimonious would be silly a-priori and not worth even
bothering with.  You would use distance methods (with much bootstrapping) if
you were in a hurry and ML methods if you wanted to write a big paper (you
would do both in fact in this case and state that the differences were
trivial (even if they are not) and you would show whichever fitted your story
best.

Note, in both cases, an interest in or knowledge of any taxonomy is not
required; just a belligerent belief in the sinister nature of the opposition
and the appropriate headgear.  If you actually knew anything about taxonomy,
you would count copepods.


Des Higgins





The Sligo man is equipped with the shortest hamstrings in Ireland,
frequently stretching themselves to near breaking point in order to
ambulate legs of orthodox length. This design fault leads to a most
jaunty and jerky gait.  Cormac MacConnell

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