Autapomorphy

[Gianluca Polgar]

If I have, say, several genera of the same family, and all of the species
of a genus (clade) "A" share a character state not shared with other
genera, this state should be called a "synapomorphy", i.e. a derived
condition appeared in the MCRA of "A" species. Right?

But if "A" includes only one species and the derived state is not present
in any other species of the family, I should continue to call that state a
"synapomorphy", or I should call it an "autapomorphy"?
In the second case, the relativity of the concept seems to be obvious; that
is "a state that is present only in one clade" relative to other clades "of
the same hierarchical level"... then I could say that the state of genus
"A" is an autapomorphy relative to other genera of the same family, but the
same state found, say, in species "a" of the same genus "A", could be
considered a synapomorphy relative to other congeneric species "b, c, d...".

Is my reasoning correct?

Thanks

Gianluca

Gianluca Polgar
Dep. of Genetics and Molec. Biol. "Charles Darwin"
Univ. La Sapienza
Roma, Italy


At 22.42 15/09/04, you wrote:
>Dear Taxacomers,
>I would like to ask about the term "autapomorphy", as I
>understand this is a character state present in a taxon that
>is not present in other taxa and is therefore
>phylogenetically uniformative.  Autapomorphies are very
>useful in creating keys and not useful in resolving
>phylogeny.  But I have heard other views that say this is a
>relative term, that clades could have a character state that
>is "autapomorphic" for that clade, in the case of broader
>(highly speciose or in ordinal level) phylogenies.  I believe
>this is a misuse of the term since that "autapomorphic"
>character state for that clade, is more appropriate to be
>called a "synapomorphy".  The term autapomorphy can never be
>realtive.  Can you help me clarify this?
>
>Many thanks,
>Vernie Sagun
>
>*******************************
>VERNIE G. SAGUN
>Center for Biodiversity
>Illinois Natural History Survey
>607 E. Peabody Dr.,
>Champaign, IL 61820-6970
>U.S.A.
>Tel: (217)244 9220
>Fax: (217)244 0729
>email: sagun at uiuc.edu
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