Encroachment and Prohibition (Science and Evolution )

[Richard Zander]

Hang on there. Cladistics may be "the best and most objective means of
reconstructing phylogeny," but there is a big jump from that to "once you
have reconstructed phylogeny".

The kicker in cladistics is that getting a multifurcation as a result of
parsimony analysis is the only acceptable time a cladist throws up his/her
hands and says geeze we can't make a decision. This is nonsense. Suppose we
have three alternative branches and one of them is supported by only one
character more than the others? E.g. when closely related branches A, B and
C are resolved as ((AB)C), but AB is supported by 3 characters and AC by 2
others and BC by 2 others? (I given this example in previous messages.
Almost nobody reacted.) Have we established a phylogeny?

If two of the three branches have their support from shared ancestry, then
the other two got their support randomly from convergence (autapomorphies
happening to be the same).  Well, support from 3 advanced characters is real
close to support from 2 advanced characters. We haven't established a
phylogeny.

You need a statistically significant number of characters supporting a
"best" arrangement of any three branches in a rooted tree against random
convergence between those three close lineages before you can say you have
established a phylogeny at some confidence level. This goes for both
morphological and molecular data.


_______________________
Richard H. Zander
Missouri Botanical Garden
PO Box 299
St. Louis, MO 63166-0299
Email: richard.zander at mobot.org

> -----Original Message-----
> From: Steeman, Fedor [SMTP:FSteeman at ZMUC.KU.DK]
> Sent: Monday, November 18, 2002 8:19 AM
> To:   TAXACOM at USOBI.ORG
> Subject:      Re: [TAXACOM] Encroachment and Prohibition (Science and
> Evolution )
>
        ...
> The cladistic method is the best and most objective one (in a matter of
> degree) to reconstruct phylogeny with. But once you have reconstructed
> phylogeny, does classification necessarily have to reflect phylogeny
> exactly?
        ...

> The bottom line: you have established a phylogeny, bravo, but let's
> include
> some extra evolutionary (phenetic) information in the classification. No
> need for doing things twice.
>
        ....

> Kind regards,
>
> Fedor Steeman
> Data Coordinator Fauna Europaea
> Zoological Museum Copenhagen
> Tel.: *45 - 353 21074
> fsteeman at zmuc.ku.dk
>
>
>
> > -----Original Message-----
> > From: john grehan [mailto:jgrehan at ADELPHIA.NET]
> > Sent: 18. november 2002 14:03
> > To: TAXACOM at USOBI.ORG
> > Subject: [TAXACOM] Encroachment and Prohibition (Science and
> > Evolution)
>