[Taxacom] Patterns of homoplasy

Bob Mesibov mesibov at southcom.com.au
Tue Aug 19 19:52:56 CDT 2008


Something similar has been happening in animals as form-controlling
genes have become (slightly) better understood. I think the spooky
implications for morphology-based 'phylogenising' were the topic of an
earlier thread on Taxacom.

I'm personally more interested in how to assess trees, independently of
the logical and mathematical processes used to generate them. A tree is
an hypothesis. Can it be tested?

Well, fossils might help, if you've got them, and I've previously
suggested here that biogeographic data could be used at appropriate
spatial and taxonomic scales to judge whether Tree A makes more sense
than Tree B.

What I'm now wondering is whether the 'bullet-tracking' in my first post
- better called 'character tracking', to free it from the JFK story -
has any potential for the evaluation of trees.

I'm particularly intrigued by the idea that character tracking could be
especially useful in examining reticulating trees, e.g. in plants. I
suppose this already happens, in a sense, as plant phylogeneticists
track cpDNA haplotypes across species of Quercus, Pinus, Alnus and
Eucalyptus. I don't know if this has yet been done with mtDNA haplotypes
in animals.
-- 
Dr Robert Mesibov
Honorary Research Associate
Queen Victoria Museum and Art Gallery and
School of Zoology, University of Tasmania
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
(03) 64371195; 61 3 64371195
http://www.qvmag.tas.gov.au/mesibov.html





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