generic oversplitting (heart of the problem)

guy REDEUILH redeuilh at CLUB-INTERNET.FR
Thu Jul 19 01:56:36 CDT 2001


Dear unknown correspondent : I swear I don't copied you...

G. Redeuilh

----- Original Message ----- 
From: Richard Pyle 
To: TAXACOM at USOBI.ORG 
Sent: Wednesday, July 18, 2001 11:06 PM
Subject: Re: generic oversplitting (heart of the problem)


> Should the scientific classification
> be aligned with our conclusions regarding how lineages have diverged, or
> should our classification be only partly reflective of that pattern,
> modified by other criterea as well. That has always been the real issue
> between cladists and "darwinians". Paraphyly is a deriviative
> issue in this dispute. Paraphyletic groups are an absurdity in the first
> perspective, and they are probably a necessary feature of the second. It
is a
> distraction to argue about them when the real issue is even more
fundamental.

This nails the basic issue, in my opinion.  The question I have always asked
when I've participated in this sort of discussion is: "Why, exactly, are we
putting labels on clusters of organisms?"  Obviously, it is to allow us to
communicate with each other -- but the question is targeted at specifically
what it is we want to communicate.  When the Linnaean system was invented,
the intent was to reflect similarity in form.  Even early taxonomists
recognized the importance of subtle detail over gross design, when they
lumped bats with mammals, rather than with birds; but it was still a
classification based on form. Somewhere along the way, the concept of
biodiversification through evolution took hold in biological circles,
providing a mechanism to serve as a foundation for the existing hierarchical
nomenclatural system.  I am not aware of any published article, or revision
in the IC_N Codes, that states, "Henceforth, the hierarchical nomenclature
shall reflect the inferred phylogeny, without regard to form or
function." -- but evidently a large segment of the taxonomic community has
shifted over to accept that premise.  Free thinkers that they are, not all
taxonomists made this shift at the same time, setting up the current
debates.

The primary opposition to the "nomenclature must strictly reflect phylogeny"
perspective comes from the early days cladistic application, when
overconfidence in comparatively weak inferences of true phylogeny led to
unprecedented instability of names.  As our ability to resolve the most
fundamental subtlety of critter/weed design (DNA) has improved, along with
improved methods for interpreting such data, so too has improved the
integrity of our inferred phylogenies, and thus the confidence that altering
nomenclature to reflect such phylogeny is (presumably) less likely to lead
to nomenclatural instability. This ability of ours continues to improve
rapidly. I can envision a day some decades hence when the vast majority of
Life's diversity has been documented (rather than the current vast minority
of documented species), and when technology will allow the entire genome of
an organism to be sequenced in seconds, and subjected to powerful and
well-tested computer algorithms that will place the organism in phylogenetic
context with enormous certainty.

But even when that day has come to pass, we may still not have answered the
question posed at the start of this message. Even when we can point with
high confidence to the correct phylogeny of a group of organisms, does that
mean that we will no longer wish to reflect in the nomenclature a
particularly divergent (in form) clade nested within a larger clade of
otherwise more or less homogeneous forms? Will it always be in the best
interest of communication amongst biologists (and lay-folk alike) that the
nomenclatural hierarchy strictly reflect the evolutionary phylogeny, without
any bias whatsoever towards the reflection of function, form, or role in the
larger ecological environment?  Perhaps -- but I submit that we (as a
community) are not yet in a position to confidently make that prediction.

I presented my own position for a solution on Taxacom last October, when
there was a lengthy discussion about Phylocode.  I don't think it's in
anyone's best interest (especially my own) to re-hash that discussion now,
so I refer the reader to the Taxacom archives.  However, I will summarize in
that I support Phylocode as a "language" that is much better designed to
reflect phylogeny in nomenclature than the Linnaean system is, considering
that the Linnaean system was never intended to strictly reflect phylogenies.
As someone who will not likely incorporate Phylocode into my own research, I
would like to see stability restored to the Linnaean system for those of us
who like to use it in a manner consistent with how it has been mostly used
for the past two and a half centuries. Eventually, as technology improves to
allow more and more reliable phylogenetic reconstruction with greater and
greater confidence, and with less and less commitment of time and effort,
the Phylocode nomenclature will expand and stabilize. Sure, there is the
risk of confusion of maintaining two separate nomenclatural systems, but
there already is confusion enough in that (at least) two separate camps are
trying to use a single system for what amounts to two separate purposes. I
also think that the transition from one system to the other will be less
painful if it is gradual, rather than abrupt. Moreover, the confusion of two
separate systems can be mitigated by including some sort of marker or flag
as an integral part of Phylocode names. It can also be mitigated if
Phylocode postpones efforts to encompass species (and ideally genera as
well), until the system has been "test-driven" for a least a few years --
but I realize that is a touchy subject in the Phylocode camp.

Finally, while I applaud Ken Kinman's efforts to help us "all just get
along" by developing a compromise system, I remain skeptical that such a
system won't end up frustrating both sides, more than serving the needs of
both.  It all comes back to the basic question that Tom DiBenedetto outlined
as quoted above. As long as we don't all share a common vision for the
purpose of biological nomenclatural classification, we'll have a difficult
time sharing a common system.

Aloha,
Rich

Richard L. Pyle
Ichthyology, Bishop Museum
1525 Bernice St., Honolulu, HI 96817
Ph: (808)848-4115, Fax: (808)847-8252
email: deepreef at bishopmuseum.org
http://www.bishopmuseum.org/bishop/HBS/pylerichard.html
"The views expressed are the author's, and not necessarily those of Bishop
Museum."




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