Hominid origins and genetic characters

[John Grehan]

At 03:57 PM 6/19/2003 +1000, Don.Colless at CSIRO.AU wrote:
>John Grehan wrote:
>
>"It seems to me to be a corollary to the current problem of genetic
>similarity analysis not being able to designate only shared derived
>states prior to analysis."
>
>I'm a bit surprised that John sees this as a problem for only the
>moleculars.

No I do not.

>And it doesn't really matter: an UNROOTED minimum length
>tree can be computed (and in principle often is, by morphologists, too)
>without any polarisation of characters, and the root then estimated by
>attaching a plausible outgroup.

Yes I am aware of this approach. I have seen it applied to morphological
studies of primate phylogeny. While it is an accepted approach I have
difficulty, at present, seeing this as anything more than simply a
parsimony analysis of phenetic (unpolarized) characters dressed up in
cladistic language.

>Shared derived states can then be read
>off the cladogram - and preferably evaluated for THEIR plausibility.

In my present understanding of the application of this approach to genetic
characters that there is no evaluation of 'plausibility' (if that is the
right word to use) - at least not in primate-hominid systematics. I suppose
I might say that my view is that the list of characters designated prior to
analysis as apomorphies for humans and orangutans does raise questions
about the plausibility of the genetic similarity being a necessary match
for phylogenetic relationship within the great apes.

John Grehan

>A
>lot more analysis could (and IMHO should) follow (but that's another
>argument!).
>
>Don C.
>
>
>Don Colless,
>Div of Entomology, CSIRO,
>GPO Box 1700,
>Canberra. 2601.
>Email: don.colless at csiro.au
>Tuz li munz est miens envirun

Dr. John Grehan
Director of Science and Collections
Buffalo Museum of Science
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http://www.sciencebuff.org/HepialidaeGate.htm