Polytomies

Eric Zurcher ericz at ENTO.CSIRO.AU
Tue Jun 17 10:10:37 CDT 1997


At 12:13 PM 6/16/97, Tom DiBenedetto wrote:
>On Mon, 16 Jun 1997 09:20:20 +1100, Eric Zurcher wrote:
>
>>Why is it that many cladists insist on regarding ALL polytomies as
>>"resolvable", and that all we need is more knowledge to resolve them? I see
>>no convincing reason why REAL polytomies cannot occur.
>
>Cladists insist on regarding all polytomies as *potentially*
>resolvable, for there is no way of knowing if any particular polytomy
>represents a real polytomy, or a lack of adequate information. Thus
>by continuing to study the problem we can hope to resolve the ones
>that need resolving. Real polytomies will resist resolution. What is
>the point of arguing against searching for more information?

Ah, there indeed is the rub! There is no way of KNOWING (at least not
reliably, via any current techniques of which I am aware) when we are in
fact looking at a true evolutionary polytomy. But I would regard a forced
or apparent "resolution" of "true" polytomies as a greater pitfall than the
failure to resolve "false" ones, for false "knowledge" is worse than mere
ignorance.

I'm certainly not arguing against searching for more information. I merely
urge caution in trying too hard to seek for a pattern which may not exist.
A few  practicing cladists seem to regard any polytomies in their trees as
a sort of embarassing failure to be overcome.

Cheers,

Eric Zurcher
CSIRO Division of Entomology
Canberra, Australia
E-mail: ericz at ento.csiro.au




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