[Annelida] Questions about total evidence

Kenneth M. Halanych ken at auburn.edu
Thu Oct 23 14:20:31 EST 2003


Kirk,

 I guess I am curious about your opinion on a few issues 
particular to "total evidence"

Can you give me a single example of a truly "total evidence paper"? I have 
never seen one. I have seen combined analyses (some are very good). 
"Moleculoids" (?) often use object criteria to filter the noise from their 
data. Similarly morphological (i.e., non-DNA or Protein) data sets are also 
filtered (either intentionally or unintentionally) by the researcher before 
analysis. That is they do not code features for which they strongly suspect 
rampant homoplasy might exist. This usually is a good thing because it cuts 
out information that does not bear on the issue at hand.  


Also do you have any theoretically problems with how to perform such 
an analysis?

I think we would both agree that a distance approach is not a good thing. 
Although parsimony is known to work well for morphological data, it has been 
clearly shown to be problematic for some types of molecular data. 
(Unfortunately parsimony is known to have more sever problems with 18S, the 
main gene currently being used for annelids, than other methods.) This leaves 
likelihood methods which work better for molecular data, but we are no where 
near developing evolutionary models for morphological. So it seems to me that 
we are currently lacking the methods to do satisfactory combined 
(molecular/nonmolecular) analysis.   

Lastly --just who is "requiring" total evidence?
 Is this another unilateral decision by George W. Bush?

Ken
-- 

************************************
Kenneth M. Halanych
Marine Biology Coordinator
Life Sciences Department
Rouse 101
Auburn University
Auburn, AL 36849

http://www.auburn.edu/academic/science_math/biology/faculty/halanych/index.html
http://www.whoi.edu/science/B/people/khalanych/kmhpage.html

Phone: (334)-844-3222
Ken's Fax:   (334)-844-2333
Biology Fax (334)-844-1645
e-mail: ken at auburn.edu


Friday Harbor Evolution of Developmental Mechanisms Class 2001
http://www.whoi.edu/science/B/people/khalanych/evodevo2001/index.html
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