Darwin (was: Phylogenetic evidence)

[Richard Jensen]

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.

Cheers,
Dick

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.
> Best!
> Zdenek

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Richard J. Jensen              TEL: 574-284-4674
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