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Re: Morpho v molecular (was Re: Tinamous: living dinosaurs)



Jura <pristichampsus@yahoo.com> wrote:


> I am in full support of Tim Williams' views on morpho vs. molecular. The only 
> folks that I have come across that accept molecules over morphology have been 
> organismal biologists. Every systematist
> I've talked to that deals with molecular phylogenies is quick to point out 
> the biases and problems associated with molecular datasets, and all are 
> strong supporters of incorporating morphology.


Yes Jason - that's my experience too.  Almost to a T.


>From Wiens 2005):

> "An obvious alternative approach to integrating molecular and fossil
> data sets is to analyze the morphological data alone (with both living
> and fossil taxa), but to use the tree from molecular data to constrain
> relationships among living taxa. A potential disadvantage of this
> approach is that the molecular tree is assumed to be true and
> unchangeable, and there is no opportunity for the morphological data to
> contribute to estimating relationships among living taxa."


Yes, this Procrustean assumption that the molecular tree is always
"right" is very dangerous.  Further, molecular matrices tend to be
expanded by the addition of more genes, rather than by the addition of
more taxa (which in many cases is not an option).  So if the genes are
leading us astray, we may be getting "bad" trees with better
(statistical) support... giving us the illusion that molecular
analyses are inherently superior to morphology-based analyses.





Cheers

Tim