Striking a balance, weighting and Cladistics

[Pierre Deleporte]

Gabriel Eickhoff raises the problem of independence between characters and
its relation to differential weighting.

I suggest that these questions would gain in being clearly disconnected.
The debate about differential weighting is implicitly developed "given that
the characters are independent".

As Kluge '89 stated it, co-occurence of characters is not a proof in itself
of their non-independence. In Gabriel Eickhoff's terms, more biological
"light" is badly needed.
Genetics of the development are presently demonstrating the influence of,
for instance, a single regulatory gene on the development of different
phenotypic features.
The discovery of such cases of non-independence should effectively lead us
to count as "one" several features completely conditioned by the same
genetic and developmental programming

This being said, the problem of differential weighting of "surviving"
supposedly independent characters remains wide open...

Pierre

>>At 10:19 PM 2/14/01, Gabriel A. Eickhoff wrote:
>  Emerson and Hastings 1998 in The Quarterly Review of Biology stated:
>   "There is a perceived difficulty in testing rigourously the causes of
>morphological character covariation (Kluge 1989) and, as a result, these
>characters are generally treated as being independent. All characters are
>given equal weiight under the assumption of character independence. This, in
>iteself, is a character weighting scheme (Wheeler 1986), one that is not
>necessarily grounded inthe biological reality."
>
>  Now, at first glance, I have to say that that argument doens't hold much
>water. At the same time, i'm compelled to reason with it because I can see
>how independence would be a form of weighting. A analogy for this could be
>made by saying, having no light on an object is just another way of seeing
>it...just without light. Assigning no weighting scheme, is just another way
>to give characters weight, just without "relative" weight.
>
>
>-Gabe
>
>
Pierre Deleporte
CNRS UMR 6552 - Station Biologique de Paimpont
F-35380 Paimpont   FRANCE
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