Encroachment and Prohibition (Science and Evolution)

[Richard Jensen]

I believe the expression that "phenetics is dead" was used in reference to choosing
a method for constructing classifications.  If one's goal is to construct a
classification that is intended to provide a hypothesis for evolutionary
relationships, then most would agree that phenetics is dead (although phenetic
methods are still used to do so in a variety of contexts).  But, phenetic
classifications can satisfy the same criteria set forth for cladistic
classifications: stability, predictivity, information content.  To my knowledge, no
one has been able to demonstrate that either phenetic or cladistic approaches are
always superior for any of the general criteria for a classification. A variety of
simulation studies have lead to differeing conclusions with respect to which
methods performed best. And, proponents of both approaches have their favorite data
sets that demonstrate the inability of the other to reflect what is known (or
assumed to be known) about the taxa in question.


I believe that Stephen is right in his comment that phenetic methods are most
valuable at the genus level and below.  After all, in the end, the things that are
being classified by cladistics are typically taxonomic entities that have been
recognized by implicit or explicit phenetic analyses.

Cheers,

Dick

STEPHEN MANNING wrote:

> At 08:03 AM 11/18/02 -0500, john grehan wrote:
> >Ken wrote:
> >>John,
> >>     What I see as "germane" is that strict cladists are increasingly
> >>encroaching on the freedom of traditional eclecticists to pursue science in
> >>their own way.
> >
> >If you are saying that cladists are preventing non-cladistic methods from
> >publication I would agree that it is a problematic situation. I still see a
> >lot of phenetic studies being published (including phenetic molecular
> >studies dressed up in cladistic terminology) so it would not seem that they
> >are entirely exclusive.
>
> This is interesting.  I remember being told, when a graduate student in the
> 1980's, that "phenetics is dead" as a methodology.  If not, my gut reaction
> is that perhaps it is still useful and used more in revisionary work at the
> genus and lower taxonomic levels, especially in relatively speciose taxa;
> and increasingly less so as one moves up the taxonomic hierarchy to family
> and higher levels.  Is there any validity to this perception?  Also, might
> it be useful to clarify the differences, if any, between phenetics and the
> non-cladistic parts of eclecticism?
> I'm not sure I see any.
>
> Cheers,
> Steve
>
> >Perhaps you could cite some publication examples
> >that you have in mind.
> >
> >>And the most vocal and extreme strict cladists make little
> >>effort to hide their contempt for those who disagree with them, sometimes
> >>commenting that they are just waiting for us "to die off".
> >
> >This kind of attitude is not confined to whether one is a vocal or extreme
> >cladist.
> >
> >>  The insistence of strict cladists that ALL paraphyletic
> >>groups must be done away with is unreasonable and one-sided.
> >
> >My view is that whether it is 'ureasonable' or 'one-sided' is less the
> >issue than whether it is a more effective (predictive) approach to the
> >structure of biological relationships. Panbiogeography is also unreasonable
> >and one-sided in not accepting centers of origin and means of dispersal as
> >an element of biogeographic analysis.
> >
> >>Arguments that paraphyly is "unnatural" are about as convincing as
> >>religious groups arguing
> >>that dancing is a sin.
> >
> >Its convincing to some and not to others.
> >
> >>     Strict cladism is seen by many as uncompromising, single-minded, and
> >>sometimes as being like an abusive spouse whose aggression just gets worse
> >>and worse over time.
> >
> >Strict cladism may be uncompromising, but that is not necessarily a
> >scientific flaw.
> >
> >>Like abused spouses, we are beginning to realize that
> >>we are not alone and increasingly banding together to fight back.
> >
> >That's the normal practice of scientific discourse - at least traditional
> >'male' oriented discourse (lots of 'fighting' - great stuff). Perhaps the
> >cover page of Hull's book on science as a process is by no means coincidental.
> >
> >>P.S.  While I agree that paraphyly has been overused in the past (and worse
> >>yet, it was usually inexplicit and often sloppy), that is no grounds for
> >>prohibiting it.
> >
> >There are grounds if one takes a purely cladistic view of phylogeny.
> >
> >>Just as Prohibition (of alcohol) in the U.S. was a bad
> >>idea, the attempted Prohibition of Paraphyly in the latter quarter of the
> >>20th Century will be seen as an extreme measure that ended up doing more
> >>harm than good.
> >
> >In which case you will be vindicated.
> >
> >John Grehan
>
> Stephen D. Manning, Ph.D.
> Professor of Biology
> Mathematics and Science Division
> Arkansas State University - Beebe
> P. O. Box 1000
> Beebe, Arkansas 72012-1000
> USA
> Tel: 501-882-7162

--
Richard J. Jensen              | tel: 574-284-4674
Department of Biology      | fax: 574-284-4716
Saint Mary's College         | e-mail: rjensen at saintmarys.edu
Notre Dame, IN 46556    | http://www.saintmarys.edu/~rjensen