[Taxacom] The Difference

Kenny Kinman kinman2001 at hotmail.com
Sun Oct 28 21:34:18 CDT 2007

Dear All,
      I only had time to quickly skim through this thread, but I am a little 
concerned that both morphological and molecular (especially the latter) are 
being painted with brushes that are too broad.  Molecular data now has a 
range from the simple (single base substitution), through slightly more 
complex (insertions/deletions of one or more bases, generally the longer the 
better), to very complex insertions/deletions that can be quite long 
(sometimes even entire sections of chromosomes).

     I think the real issue here should be complexity of a character, not 
whether it is morphological or molecular.  If a molecular data set includes 
only simple base subtitutions, then it shouldn't be mixed with complex 
morphological characters (or even complex molecular characters, for that 
matter), at least initially.  You can then go ahead and mix simple and 
complex characters in another analysis, but you'd better weight them in AT 
LEAST some crude fashion (low weight, moderate weight, high weight).

      But there are now complex molecular characters that are probably far 
more reliable than some simple morphological characters, so the ideal 
analysis would include all complex characters (morphological and molecular). 
  If you want to include simpler characters (of either kind), you'd better 
weight them appropriately so they don't dilute the phylogenetic signal from 
those that are more complex.
     ---Ken Kinman

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