[Taxacom] cladistic analysis of characters with variable presence

John Grehan jgrehan at sciencebuff.org
Wed Jul 13 13:09:52 CDT 2011

This question is directed to any on this list who work with cladistics
and feel they may be able to comment. 


A recent paper on primate anatomy and phylogeny did a cladistic analysis
for characters where the derived character states were variable in the
population of each species. Thus, character A might have a derived state
that occurred only in the in-group, but in 20% of individuals for taxon
1, 50% of individuals of taxon 2, and 90% of taxon 3. These taxa were
coded such that species with a higher proportion of individuals with the
derived state were coded as being more derived.


My question is whether the varying proportions of a character state in
different species can be considered to represent a phylogenetic signal -
i.e. that they are a constant of the taxa involved and invariable over
time so those proportions represent a shared derived state. Intuitively
I think this would not be cladistically valid, but rather an artifact of
population dynamics at any one time. Someone must (?) have commented on
this in the literature - in which case I would be very interested to
know those views.


John Grehan 


Dr. John R. Grehan
Director of Science and Research
Buffalo Museum of Science
1020 Humboldt Parkway
Buffalo, NY 14211-1193

email: jgrehan at sciencebuff.org
Phone: (716) 896-5200 ext 372
Fax: (716) 897-6723


Ghost moth research

Human evolution and the great apes


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