RE: Deep Scaly Project

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: david peters [mailto:davidrpeters@earthlink.net]
> Sent: Monday, May 16, 2005 5:36 PM
>
>
> I can't tell you how much I agree with your thoughts here, Tom.
>
> Re: the number of characters, I was wondering if you, or anyone else, had any 
> thoughts concerning Chippendale and Wiens
> 1994 (Systematic Biology 432: 278-287) theoretical work that seemed to 
> indicate that only 150 or so characters were
> needed to bring the probability of estimating correct phylogeny to the 95th 
> percentile (rapidly evolving characters),
> while 300 skirts the 99th.
>
In a word: EEK!!! The Bull et al. 1993 paper, to which the Chippindale & Wiens 
paper is a response and modification, is a simulation
of molecular evolution in a FOUR TAXON tree!!! It isn't some figure which can 
universally be applied to all trees of all size. So
no, 150 or 300 is by no means some magic number that can be applied to every 
analysis.

To think about it a different way, the Deep Scaly Project matrix is about 150 
terminal taxa. Yet one would hope for more than 1
character per node on a (e.g.) a fully pectinate tree.

As for if I or anyone else had thoughts on the subject: the last decade's worth 
of Systematic Biology and Cladistics have had
numerous articles in the "more characters vs. more taxa" (or "data density") 
sphere of discussion. I will say that as far as I have
read, there is no resolution to a single magic answer. Just in general: data is 
good, more data is better.

P.S. Weins himself is part of the Deep Scaly Project; his website of his 
publications is
http://life.bio.sunysb.edu/ee/wienslab/publicationpage.html. On it are several 
papers relevant to this discussion.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

http://www.geol.umd.edu/~tholtz/
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796
>