[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Deep Scaly Project

Thanks for debunking the magic, Tom.

I never heard of Wiens's work until a reviewer was shocked that  had not 
referenced it. Now I've heard its praise and a cautionary
note. All part of my education.


"Thomas R. Holtz, Jr." wrote:

> > 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
> >