[Taxacom] "Tenuinucelli" clade in eudicots?

Pierre Deleporte pierre.deleporte at univ-rennes1.fr
Tue Mar 1 11:51:58 CST 2011


Sorry, but no :

there is no "cladistic" principle that distant taxa cannot share a 
synapomorphy,
there is a principle that this can also be a case of convergence

now the question is: what "cost" (or verisimilitude) do we attribute to 
the implied processes in both scenarios: repetitive apparition, or 
disparition, of the concerned trait... and how many times

Pierre



Richard Zander wrote:
> 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. :)
>
> jim
>
>
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