use of morphological characters
Tue May 2 08:39:11 CDT 2000
I was trying to find literature on alternative applications of morphological
characters for cladistic analyses, in particular, papers discussing binary vs.
multistate characters, independence of characters, splitting of
characters, etc. All I could find was Pimentel & Riggins 'The nature of
cladistic data' (1987), which didn't really answer the problem I had in mind.
To illustrate my quest: Instead of coding certain features of appendage A (of an
arthropod) as a multistate character, it is also possible to split the character
states into separate characters. For example, my first character
would be: appendage A = absent/present. 2nd character = whole appendage
long/whole appendage short. 3rd character = reduced number of segments/number of
segments not reduced. 4th character = proximal segments narrow/proximal segments
In my opinion, this method is highly questionable. First to note, all taxa with
state 'absent' for the 1st character would have to be scored as '?' or '-' for
the following characters (2-4). As far as I know, PAUP fills in the
missing states with the most parsimonious solution, which would be contradictory
in this case (an absent appendage cannot be short).
Secondly, I would suspect the above characters, or at least some of them, to be
dependent, e.g. the length of the appendage could be ontogenetically connected
with a reduction of segments, etc.
Also, literature tips on this matter are much appreciated!
Dept. of Biological Sciences
Old Dominion University
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