Derek Sikes dsikes at UCALGARY.CA
Tue Sep 21 09:55:47 CDT 2004


Autapomorphies are not informative in Parsimony analyses but are
informative in common-mechanism model based analyses (aka Maximum
Likelihood). See Lewis, 2001 Sys Bio 50(6): 913-925 [section on the
"autapomorphy trail"]. This feature, incidentally, is one of the key
distinctions between these methods that reduces the error rate of
Maximum Likelihood relative to Parsimony with trees showing extreme
branch-length heterogeneity.


On 15-Sep-04, at 3:30 PM, Michael Ivie wrote:

> Dear Vernie,
> Autapomorphies are, by definition, not informative at the level of
> universality under investigation, but the character state may be
> informative at other levels of universality (by definition no longer an
> autapomorphy).  If "level of universality" is an unfamiliar term,
> please
> refer to basic textbooks such as Wiley, E. O.  1981.  Phylogenetics.
> Wiley & Sons New York.  Also, your definition of autapomorphy is
> incorrect.  See the same reference for a correct definition.  I am sure
> there are many copies of this reference kicking around the Survey staff
> offices.
> Mike
> On Wed, 15 Sep 2004, Vernie Sagun 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
>> *******************************
>> 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
>> *******************************
Derek S. Sikes, Assistant Professor
Division of Zoology
Department of Biological Sciences
University of Calgary
2500 University Drive NW
Calgary, Alberta, Canada, T2N 1N4

dsikes at

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