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Date: Wed, 04 Feb 2004 15:02:17 +0300
From: "Igor Ya. Pavlinov" <igor_pavlinov@zmmu.msu.ru>
To: PhyloCode <phylocode@ouvaxa.cats.ohiou.edu>
Subject: Re: a comment on ancestors
Dear Michel, just few additional comments >Do you see any problems with a definition of the kind: >the smallest clade that includes species A and B? Yes, there is the problem, because one matter is to define a taxon of known things and another is to allocate to it some other previously anknown thing. How can you base belonging of species C to the clade A+B without unambiguous indication of chars (be they synapomorphies) uniting all of them? That is why characters used in taxon definition do matter: if you use another set of characters in a new cladistic analysis and get to another cladistic classification, you will never answer the question about (supposed) belonging of your newly discovered object to any taxon in previously established taxa. Again, two logically different procedures are mixed here: one is testing the existing classification by another set of chars, and another is adding a new object to the existing classification. Again, we (or me, at least) come to a conclusion that taxon and taxon name definitions deserve more close consideration from epistemological, logical, theoretical, pragmatic etc viewpoint before saggesting it to taxonomic community. Thanks for the paper and for the list of publication. Sorry I don't read French. Igor ----- Original Message ----- From: Michel Laurin <laurin@ccr.jussieu.fr> To: Igor Ya. Pavlinov <igor_pavlinov@zmmu.msu.ru> Sent: Wednesday, February 04, 2004 12:59 PM Subject: Re: a comment on ancestors > Dear Igor, > > >Well, then we have to go to the theory of definitions to look if reference > >to something which is not presumed (because of impossibility) to explore is > >the definition at all. If you define a taxon by a character or by a type you > >mean that it is possible to allocate any newly discovered item to that taxon > >by observing respective character or type. The present PhyloCode definition > >of taxon membership presumes that in order to allocate a new item to one or > >another monophyletic group in existing classification, one has to run > >complete cladistic analysis in which all members of those groups + new item > >are to be included. > > Yes, that is correct. > > >But what to do if those groups were recognized, say, by > >DNA analysis and no DNA data are vailable for the new item? > > I would say that this does not matter as > long as a phylogeny of the group can be produced > (using other kinds of evidence). > > >It seems to me that theoretical and empirical definitions of taxon > >membership are mixed in the PhyloCode. > > Here, I believe that you are correct. I > don't view this as a problem because I have a > more practical approach to PN, but I admit that > it might be better to use more operational > definitions, from certain points of view. Do you > see any problems with a definition of the kind: > the smallest clade that includes species A and B? > > >At any rate, I think that PhyloCode definition of taxon membership is to be > >more seriuosly investigated by some logicians. > > I think that it will be. > > Sincerely, > > Michel > > >Igor > > > >----- Original Message ----- > >From: Philip Cantino <cantino@ohiou.edu> > >To: Igor Ya. Pavlinov <igor_pavlinov@zmmu.msu.ru> > >Sent: Tuesday, February 03, 2004 9:57 PM > >Subject: Re: a comment on ancestors > > > > > >> Dear Dr. Pavlinov, > >> > >> Some of the phylogenetic definitions used in the PhyloCode (see Note > >> 9.4.1) refer to "the most recent common ancestor" but one does not > >> have to be able to recognize the ancestor in order to use the > >> definition. Furthermore, each definition type has at least one > >> recommended wording that does not refer to ancestors (e.g., the least > >> inclusive clade containing A and B). Again, I refer you to Note > >> 9.4.1. > >> > >> Sincerely, > >> Phil Cantino > >> > >> > >> >I'd like to call your attention to the following. > >> > > >> >From the vary beginning of claditstics, the concept of the > >> >species-as-ancestor was acknowledged as non-operational one, as > >> >there is no practical criteria for recognizing a particular species > >> >as the ancestor of a particular monophyletic group. That is why > >> >concept of sister group is more consistent with initial epistemology > >> >conditions of the new phylogenetics. I wonder if the PhyloCode in > >> >its present version is consistent and operational in respect to > >> >definition of taxa and their names by refernce to > >> >species-as-ancestor. > >> > > >> >Thank you. > >> >- - - > >> >Dr. Igor Ya. Pavlinov > >> >Chief, Division of Mammals > >> >Zoological Museum > >> >Moscow M.V.Lomonosov State University > >> >ul. Bol. Nikitskya, 6 > >> >125009 Moscow > >> >Russia > >> >Tel.: (095)2032940 > >> >Fax: (095)2032717 > >> >E-mail: <mailto:igor_pavlinov@zmmu.msu.ru>igor_pavlinov@zmmu.msu.ru > >> > > >> > >> > >> -- > >> Philip D. Cantino > >> Professor and Associate Chair > >> Department of Environmental and Plant Biology > >> Ohio University > >> Athens, OH 45701-2979 > >> U.S.A. > >> > >> Phone: (740) 593-1128; 593-1126 > >> Fax: (740) 593-1130 > >> e-mail: cantino@ohio.edu > > > -- > Michel Laurin > FRE 2696, CNRS > Universit? Paris 7 - Denis Diderot > 2, place Jussieu > case 7077 > 75005 Paris > FRANCE > > tel. (33 1) 44 27 36 92 > fax. (33 1) 44 27 56 53 > http://tolweb.org/tree/laurin/Laurin_Home_page.html