arbitrariness

Nico M. Franz nmf2 at CORNELL.EDU
Thu Jul 3 18:56:51 CDT 2003


Sure, I can try.

(1) Even though it's clear to anyone interested that ranks within mammals
vs. insects aren't evolutionarily comparable, LOCALLY they do convey
relational information and perhaps even a hunch of amounts of
transformation. How else could one explain that some systematists are
called lumpers or splitters while others are said to do something reasonable?

(2) Suppose I do a cladistic analysis and get to name a genus. In fact the
structure of my cladogram is such that I could make the "cut" for my new
genus at three different places. Of those I select the one that is
associated with the clearest externally visible morphological differences
(what evolutionary taxonomists tend to call "gestalt"), and maybe an
interesting biological observation I made in the field. Now suppose that I
did this 25 years ago, and by now more inclusive studies have not only
confirmed the monophyly of my genus, but also generated a whole bunch of
noteworthy evolutionary results for members within it. So basically now we
have a communication vehicle that exclusively delimits not only a
monophyletic group, but also a load of morphology, cladistic hypothesis
testing, and unique evolutionary history. Whenever the name (and rank) of
the taxon is mentioned, this information may get transported with it. Even
people getting the information fundamentally wrong can still talk about the
same evolutionary lineage! The meaning of the name becomes more and more
enriched as we learn more about this lineage (this in spite of the
arbitrariness of the initial baptism). Of course this supposes that a
phylogenetic perspective is a good thing to acquire for a biological name.
Conversely, if I got the genus wrong and none of these regularities would
obtain, the name won't function in this way for communication among biologists.

At one point I happened to study the behavior of members in the ant genus
Ectatomma. These are not only "easy" to tell in the field, but anyone who
studies closely related ants associates a whole bunch of other things -
exclusively - with the name Ectatomma. I think this is possible because
there is a sufficiently precise match between the nestedness of names in
classification and the nestedness of evolutionary phenomena out there in
nature. As I said, regular names can be fixed once and that's it because
they don't need to convey historical nested information (like ranks can).
Other biologists such as behaviorists though appreciate the ability to load
up names with relevant information, which can thus acquire an incredibly
valuable role for communication. Linnean names need be revised precisely
because they were designed to entail so much meaning. It's not clear to me
at all (and I'd be interested in a response) that rankless names will not
disrupt communication inside and outside of an entire scientific tradition.

At 02:25 PM 7/3/2003 -0700, T. Michael Keesey wrote:
> > Although the initial baptism of a ranked taxon bears an element of
> > arbitrariness, the meaning they receive (or lose) over decades of research
> > is anything but that.
>
>Perhaps if you could give an example.
>
>=====> T. Michael Keesey <keesey at bigfoot.com>




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