Darwin (was: Phylogenetic evidence)

SKÁLA Zdenek skala at INCOMA.CZ
Fri Jul 26 12:28:22 CDT 2002

Perhaps I was not clear enough, so:

>In A, it takes the form of a derived "0", which is a plain historical avatar of "1".
>The class DCBA is supported by the shared equivalent trait "1" = "derived
>0" in A.
I agree completely with the only reservation that class theory knows nothing about history but only on the objects and characters, so the argument that 'historically 0=1' is invalid in this context (and hence: the clades are not classes). This also points to the second paragraph...:

>independent-a-priori-indistinguishable-apomorphies, ARE homoplasies, by 
>definition ! ...etc.
There are two options:
1. Either the "-1" in A is different from "-1" in plesio-lines below D (plesiomorphy) and then "-1" in A is different from "-1"  in e.g. X (let's suppose that these last two are apomorphies). But if these are non-equivalent character states then they are not homoplastic (like -1 is not homoplastic with e.g. +8). Homoplasy only can be defined as a consequence of character state equivalence appearing in distant lines  - e.g. when -1 is always "the same" though appearing several times (this is the meaning of the words "character conflict").Without character conflicts you will always get a fully resolved cladogram.
2. Or one accepts character-state equivalence (i.e. "-1" is always the same) resulting in the homoplastic character states / character conflicts. This, however, in turn means that these apomorphies/homoplasies are also equivalent to the plesiomorphic state and then ... (clades are not classes).


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