Oragnutan relationships

pierre deleporte pierre.deleporte at UNIV-RENNES1.FR
Fri Apr 12 18:54:11 CDT 2002


A 12:27 12/04/2002 -0400, Bj Burger wrote :
>>>constructing phylogenetic hypotheses.  In any case, regardless of the
>>>nature of
>>>the data or the form of analysis, one cannot identify a character as a
>>>synapomorphy until a phylogenetic hypothesis has been made (i.e., the
>>>data
>>>have
>>>been used to construct a phylogenetic tree).
>
>I've noticed confused over these terms.
>Synapomorphies = Derived characters that unite two groups into a
>monophyletic group after a phylogenic analysis.
>Is there another term for derived characters that are shared between two
>groups, before a phylogenic analysis?


Apo- / Plesiomorphy is a relative notion, apo is relatively derived, plesio
relatively ancestral character state (of a given homologous character).
Synapomorphy is homology taken at the level of generality where it defines
a monophyletic group (see e.g. Wiley 1975).

Homology assessed before phylogenetic analysis is putative homology (sensu
de Pinna 1991), it is confirmed homology after the analysis (if confirmed
of course; if not, it breaks into homoplasies). We could thus talk of
putative synapomorphy as well for a character state a priori considered as
putatively derived relatively to another character state putatively
relatively ancestral (putatively plesiomorphic). Putative synapomorphy /
symplesiomorphy is the result of putative homology and polarity statements
before phylogenetic analysis (phylogeny inference + its consequences for
character homology).

Pierre




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