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Re: Genetics and Morphology Collide



Dinogeorge wrote (02/09/96; 9:12p):

>In a message dated 96-02-09 17:04:48 EST, nking.ucs@smtp.usi.edu (King, 
>Norm) writes:

>>Of course, there is always the danger that synapomorphies used in 
>>constructing cladograms actually do not have phylogenetic significance. 


>This sentence contains a common but interesting misusage of the term
>"synapomorphy." Synapomorphies _cannot_ lack phylogenetic significance; 
only
>apomorphies can. Synapomorphies are not used _to construct_ cladograms; 
only
>apomorphies are. The synapomorphies emerge from among the apomorphies in 
the
>analysis _after_ the cladogram is constructed: they are precisely the
>apomorphies _with_ phylogenetic significance!

Let me get this straight:  apomorphies are observations--the physical 
characteristics we think we see.  They are used to construct cladograms.  
The cladogram branches at certain points, and the characters possessed in 
common by the members of a branch are called synapomorphies--still an 
observation.  

But wouldn't it be an _interpretation_ that the observed synapomorphies 
have phylogenetic significance?


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Norman R. King                                       tel:  (812) 464-1794
Department of Geosciences                            fax:  (812) 464-1960
University of Southern Indiana
8600 University Blvd.
Evansville, IN 47712                      e-mail:  nking.ucs@smtp.usi.edu