Fwd: Re: Farewell to Species - reticulation

[Hubert Turner]

On 01 Feb 2000 11:25:03 -0600, Thomas Lammers wrote:

>And it is exactly the sort of misconception that arises when we worry so
>much about making pretty patterns of stick-figures that we lose sight of
>the real live organisms and biological processes that our patterns are
>meant to represent.

You mean those fancy containers for the different DNA sequences
we want to classify ;-) ?

>cladistics is flawed science because it comes to a conclusion first ("all
>evolution is dichotomously divergent, with ancestors becoming extinct at
>the appearance of a pair of daughter-taxa") and then seeks data to support
>that conclusion.


This is only flawed if your definition of an ancestor [species;
or as a matter of fact of any species] is different from something
like: a [group of] part[s] of the genealogical network between two
permanent splits. The reason is that cladistic analysis can only
reconstruct the relative temporal order between permanent splits, and
therefore the actual and hypothetical units recognised by such an
analysis (terminal units and "ancestors") will in some way
or another have to be delimited by such splits. Not necessarily all
permanent splits: a cladistic analysis on clades as terminal units is
OK. Thus, cladistics does not require per se that species are
monophyletic unts. See, e.g., the work of D.J. Kornet on the species
problem.

Hubert Turner


*******************************************************
Dr. Hubert Turner
EEW, Sect. Theoretical Biology & Phylogenetics
PO Box 9516, 2300 RA  Leiden, The Netherlands
Visiting address: Van der Klaauw Laboratory, Kaiserstraat 63, Leiden
Phone: +31-71-5274904    Fax: +31-71-5274900
E-mail: turner at rulsfb.leidenuniv.nl
WWW: http://wwwbio.leidenuniv.nl/~turner/index.html

FROM 18 JANUARY TILL MID-APRIL I WILL BE VISITING THE NEW YORK
BOTANICAL GARDEN AS VISITING SCHOLAR, DOING MOLECULAR
PHYLOGENETIC RESEARCH ON ANACARDIACEAE. THIS E-MAIL ADDRESS
WILL REMAIN FUNCTIONAL DURING THAT PERIOD.
*******************************************************