Darwin (was: Phylogenetic evidence)
rjensen at SAINTMARYS.EDU
Thu Jul 25 12:24:25 CDT 2002
Ok, I see what you mean - there is no single apomorphy held in common by all members of the clade; with respect to these characters, the clade is polythetic. I interpreted your original statement to say the that no one of the character states (across all characters) were shared by members of the clade. A "semantic" problem - not a real problem.
SKÁLA Zdenek wrote:
> -----Original Message-----
> From: Richard Jensen
> If I take this literally, then you are arguing that there can exist a clade in which the objects have absolutely nothing in common ("...members do not share any character state in common..."). If that's the case, then the "clade" does not exist - it cannot be supported by any evidence and, in my mind, consists of two mutually exclusive classes of unknown affinity.
> Can you provide an example of such a clade?
> Um, am I wrong here? What about the character matrix (+ = apomorphy)
> 1 2 3 4 5 6 7 8
> A - + + + + + + +
> B + - + + + + + +
> C + + - + - - + +
> D + + + - - - - -
> ... does not it result in a cladogram (((AB)C)D) ? If yes (and perhaps I am missing something here), then we have a clade ABCD where the species do not share any single common character state.
Richard J. Jensen TEL: 574-284-4674
Department of Biology FAX: 574-284-4716
Saint Mary's College E-mail: rjensen at saintmarys.edu
Notre Dame, IN 46556 http://www.saintmarys.edu/~rjensen
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