[Taxacom] "Tenuinucelli" clade in eudicots?

John Grehan jgrehan at sciencebuff.org
Tue Mar 1 11:53:36 CST 2011

"Why can't taxa somewhat distant on a tree have synapomorphies?"

I presume this means the 'same synapomorphies' - otherwise the question would not make sense (since taxa on any tree can have synapomorphies). But if a distant tree is distant, then the similarities do not of themselves appear as synapomorphies, but their distribution may be congruent with a pattern of relationship encompassing the two groups that are established by other characters such that they might be considered to have been lost in those taxa where they are not present.

At least that's the way I would reason it - not that I cam a cladistic theorist (nothing like expressing opinions out of ignorance)

John Grehan

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Richard Zander
Sent: Tuesday, March 01, 2011 12:24 PM
To: Jim Croft
Cc: taxacom at mailman.nhm.ku.edu; Kenneth Kinman
Subject: Re: [Taxacom] "Tenuinucelli" clade in eudicots?

One of the problems with cladistics is that it has lots of principles about how things should be done. One of the principles is that only sister groups can have synapomorphies. Why can't taxa somewhat distant on a tree have synapomorphies? All this means is that they have a deep shared ancestor at that taxon level.

Thus, Jim, your discussion of " agreement on the shared traits" assumes that only agreement is necessary for systematics to proceed. But, no, simply agreeing on a nonfalsifiabe nonscience principle does not advance science. {{macro)). 

* * * * * * * * * * * * 
Richard H. Zander 
Missouri Botanical Garden, PO Box 299, St. Louis, MO 63166-0299 USA 
Web sites: http://www.mobot.org/plantscience/resbot/ and http://www.mobot.org/plantscience/bfna/bfnamenu.htm
Modern Evolutionary Systematics Web site: http://www.mobot.org/plantscience/resbot/21EvSy.htm

-----Original Message-----
From: Jim Croft [mailto:jim.croft at gmail.com] 
Sent: Tuesday, March 01, 2011 12:01 AM
To: Richard Zander
Cc: Kenneth Kinman; taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] "Tenuinucelli" clade in eudicots?
That is what I would have thought. The evidence is that taxa as circumscribed have certain characters, with some toing and froing about whether these are indeed the same characters wit the same origin or only apparently so.  Whether this and the names are step 0, or even step -1, I am not fussed.

Once we have agreement on the shared traits (the evidence), the mechanism of how those shared states may have got there is the hypothesis, not the evidence. And then the polemic and story-telling begins. :)



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