RE: stratocladistics

[Toby White <augwhite@neosoft.com>]

In last week's issue of Science (which I've already mislaid) is a great 
exchange of letters between three paleoanthro groups.  The controversy there is 
essentially on "sampling" problems related to character selection.  Melanie 
McCollum's point (worked out in more detail in her Science article a few months 
ago) is that cladistic results are easily skewed if you keep sampling 
characters from the same developmental module.  For example there are only so 
many ways to make a robust jaw apparatus out of the basic Australopithecine 
chewing machinery.  The developmental biology then dictates  certain changes in 
palate, nares, etc so that many characters of these structures cannot be 
regarded as independent.

If McCollum's analysis is correct and more broadly applicable (big "ifs" to be 
sure) how much worse off are we when we include stratigraphic information? 
 Stratigraphic data does suffer in that the sampling is neither uniform nor 
necessarily independent.  I'm not advocating Fox's approach which quite 
possible places too much reliance on stratigraphy.  However, I don't see why 
the consideration of at least relative stratigraphic position might not be one 
of several sorts of information to consider.  Is the quality of this data any 
worse than the information we already use for cladistics?

  --Toby White

On Tuesday, August 31, 1999 9:19 AM, chris brochu [SMTP:cbrochu@fmppr.fmnh.org] 
wrote:
> Gang,
>
>       Not long ago, someone asked about the recent Fox et al. paper in
> Science that, on the surface, seemed to indicate the superiority of
> stratocladistics over more conventional cladistics.  Y'all might be
> interested in a comment Science recently put on its web site:
>
> http://www.sciencemag.org/cgi/content/full/285/5431/1179a
>
>
> This consists of a comment and reply.  I agree with some aspects of the
> comment, but not all of them; likewise with Fox et al.'s reply.
>
> One thing the comment does not address is the unsuitability of
> stratocladistics when biogeographic sampling is nonuniform.  If anyone
> can tell me of a terrestrial vertebrate lineage with uniform, unbiased
> biogeographic sampling, I will happily delve into stratocladistics.
>
>
> chris
>
>
>
> --
> ----------------------
> Christopher A. Brochu
> Department of Geology
> Field Museum of Natural History
> Roosevelt Road at Lake Shore Drive
> Chicago, IL 60605
>
> voice: 312-665-7633  (NEW)
> fax: 312-665-7641 (NEW)
> electronic:  cbrochu@fmppr.fmnh.org