outgroup versus ordered characters in Cladistics

[Olivier De Clerck]

Dear all,

Recently we were wondering in the department about the difference
between defining an outgroup in a parsimony analysis and explicitely
stating that the characters are ordered.

If one creates an outgroup in  a parsimony analysis, which has a
0-value for a two-state character, does this automatically mean that
the 1-value is the apomorphic state and 0-value the plesiomorphic
state? I would presume it is. BUT what is in this case the additional
value of defining that the characters are ordered (0-value =
plesiomorphic ; 1-value = apomorphic)?

Additional question: is there a difference between Hennig86 and Paup
on this point?

Looking forward hearing from you,

Olivier De Clerck.


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Dr. Olivier De Clerck
Dept. Biology
K.L.Ledeganckstraat 35 - B-9000 Gent, Belgium
tel 9-264.50.64 / fax 9-264.53.34 / olivier.declerck at rug.ac.be

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