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Re: Whales and Hippos




I don't necessarily disagree with what was written below (though I didn't think the Sys Bio paper by Naylor and Adams was all that great); however, y'all should pay attention to some of the work Jess Theodor is doing with the molecular side. The short answer is that the molecular signal is not as clear-cut as recent publications would lead one to believe. Her work is not yet published, so I won't say more.




chris



We don't need to find Mesonychian DNA if the molecular data strongly support the nesting of Whales WITHIN the clade bracketed by modern artiodactyls. Of course the molecular data are useless for distinguishing between the "whales as basal artiodactyls" and "whales as advanced mesonychians" Yes the tooth data support whales as mesonychians but nothing else does. Not several independant molecular data sources (different genes, SINES etc.) nor postcranial anatomy. There was a good paper about this a few months ago in Systematic Biology. I believe this is the way forward in systematics. Don't just throw everything together and see which signal wins out in raw total evidence approach. Examine as many independent, or nearly independant sources of data as possible and see which ones are agreement and which ones are not. In this case we find everything, except teeth, supports the Whales as artiodactyls hypothesis. I am therefore inclined to accept that the tooth data is being misleading through the action of extreme convergence. Another problem with the tooth data is that it may be inflated through non-independance of the characters, ie. a bump in the upper molar and a corresponding hollow in the lower molar should be one character, not two.

cheers

adam Yates


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------------------------
Christopher A. Brochu
Assistant Professor
Department of Geoscience
University of Iowa
Iowa City, IA 52242

christopher-brochu@uiowa.edu
319-353-1808 phone
319-335-1821 fax