nominal characters

[Curtis Clark]

Date sent: 95.4.7
Richard Jensen wrote:
 >Ordering of two state characters may be implicit, but unless we know the
 >evolutionary origin (e.g., for my example of fruit maturation in oaks:
 >annual vs. biennial), we can't be sure of the ordering.  Simply coding
 >one as 0 and the other as 1 does not validate the "order."  Whic way is
 >it, 1-->0  or 0-->1?  While the order is unchanged, the interpretation is
 >quite different.  This will be important for cladistic analyses in which
 >the transformation series needs to be included (of course, parsimony
 >methods can be applied to unordered data).

But if we are truly talking about biological ordering and not simply
mathematical coding, then wouldn't Mr Fortuner's statement become,
"If a character exists that has not evolved from another character, nor
evolved into another character, it cannot be present in a valid species
in more than one state"?  If a character has more than one state, doesn't
that imply biological ordering? (Either A=>B, or B=>A, or some other
state gave rise to A and B.)  So if the only nominal characters have
only a single state, his statement is a tautology.

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Curtis Clark                                       Voice: (909) 869-4062
Biological Sciences Department                     FAX:   (909) 869-4396
California State Polytechnic University, Pomona
Pomona CA 91768-4032                               jcclark at csupomona.edu
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