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Date: Tue, 12 Aug 2003 09:25:45 -0400 (EDT)
From: StephanPickering@cs.com
To: phylocode@ouvaxa.cats.ohiou.edu
Subject: phlyogenetic systematics/the PhyloCode -- new philosophical overview
--Boundary_(ID_ZJ7bwk/F/Q1997MX2Vq9ew) Content-type: text/plain; charset="US-ASCII" Content-transfer-encoding: 7bit Journal of Zoological Systematics & Evolutionary Research Volume 41(3):162-174 -- August 2003 doi:10.1046/j.1439-0469.2003.00236.x Ceci n'est pas une pipe: names, clades and phylogenetic nomenclature Fredrik Pleijel and G. W. Rouse ABSTRACT An introduction is provided to the literature and to issues relating to phylogenetic nomenclature and the PhyloCode, together with a critique of the current Linnaean system of nomenclature. The Linnaean nomenclature fixes taxon names with types, and associates the names with ranks (genus, family, etc.). In phylogenetic nomenclature, names are instead defined with reference to cladistic relationships, and the names are not associated with ranks. We argue that taxon names under the Linnaean system are unclear in meaning and provide unstable group-name associations, notwithstanding whether or not there are agreements on relationships. Furthermore, the Linnaean rank assignments lack justification and invite unwarranted comparisons across taxa. On the contrary, the intention of taxon names in phylogenetic nomenclature is clear and stable, and the application of the names will be unambiguous under any given cladistic hypothesis. The extension of the names reflects current knowledge of relationships, and will shift as new hypotheses are forwarded. The extension of phylogenetic names is, therefore, clear but is associated to (and thus dependent upon) cladistic hypotheses. Stability in content can be maximized with carefully formulated name definitions. A phylogenetic nomenclature will shift the focus from discussions of taxon names towards the understanding of relationships. Also, we contend that species should not be recognized as taxonomic units. The term 'species' is ambiguous, it mixes several distinct classes of entities, and there is a large gap between most of the actual concepts and the evidence available to identify the entities. Instead, we argue that only clades should be recognized. Among these, it is useful to tag the smallest named clades, which all represent non-overlapping groups. Such taxa - LITUs (Least Inclusive Taxonomic Units) - are distinguished from more inclusive clades by being spelled with lower-case initial letter. In contrast to species, LITUs are conceptually straightforward and are, like other clades, identified by apomorphies. STEPHAN PICKERING / Chofetz Chayim ben-Avraham The Dinosaur Fractals Project 2333 Portola Drive # 4 Santa Cruz, California 95062-4250 USA stephanpickering@cs.com website: http://groups.yahoo.com/group/paleo_bio_dinosaur_ontology theropod research summarized: <www.dinodata.net> see under PICKERING at their Reference Base --Boundary_(ID_ZJ7bwk/F/Q1997MX2Vq9ew) Content-type: text/html; charset="US-ASCII" Content-transfer-encoding: quoted-printable <HTML><FONT FACE=3Darial,helvetica><FONT SIZE=3D2 FAMILY=3D"SANSSERIF" FACE= =3D"Arial" LANG=3D"0">Journal of Zoological Systematics & Evolutionary R= esearch=20 <BR>Volume 41(3):162-174 -- August 2003=20 <BR>doi:10.1046/j.1439-0469.2003.00236.x=20 <BR> <BR>Ceci n'est pas une pipe: names, clades and phylogenetic nomenclature=20 <BR>Fredrik Pleijel and G. W. Rouse=20 <BR><B>ABSTRACT</B>=20 <BR>An introduction is provided to the literature and to issues relating to=20= phylogenetic nomenclature and the PhyloCode, together with a critique of the= current Linnaean system of nomenclature. The Linnaean nomenclature fixes ta= xon names with types, and associates the names with ranks (genus, family, et= c.). In phylogenetic nomenclature, names are instead defined with reference=20= to cladistic relationships, and the names are not associated with ranks. We=20= argue that taxon names under the Linnaean system are unclear in meaning and=20= provide unstable group-name associations, notwithstanding whether or not the= re are agreements on relationships. Furthermore, the Linnaean rank assignmen= ts lack justification and invite unwarranted comparisons across taxa. On the= contrary, the intention of taxon names in phylogenetic nomenclature is clea= r and stable, and the application of the names will be unambiguous under any= given cladistic hypothesis. The extension of the names reflects current kno= wledge of relationships, and will shift as new hypotheses are forwarded. The= extension of phylogenetic names is, therefore, clear but is associated to (= and thus dependent upon) cladistic hypotheses. Stability in content can be m= aximized with carefully formulated name definitions. A phylogenetic nomencla= ture will shift the focus from discussions of taxon names towards the unders= tanding of relationships. Also, we contend that species should not be recogn= ized as taxonomic units. The term 'species' is ambiguous, it mixes several d= istinct classes of entities, and there is a large gap between most of the ac= tual concepts and the evidence available to identify the entities. Instead,=20= we argue that only clades should be recognized. Among these, it is useful to= tag the smallest named clades, which all represent non-overlapping groups.=20= Such taxa - LITUs (Least Inclusive Taxonomic Units) - are distinguishe= d from more inclusive clades by being spelled with lower-case initial letter= . In contrast to species, LITUs are conceptually straightforward and are, li= ke other clades, identified by apomorphies.=20 <BR> <BR></FONT><FONT COLOR=3D"#000000" SIZE=3D3 FAMILY=3D"SANSSERIF" FACE=3D"Ar= ial" LANG=3D"0"></FONT><FONT COLOR=3D"#000000" SIZE=3D2 FAMILY=3D"SANSSERIF= " FACE=3D"Arial" LANG=3D"0"> <BR> <BR></FONT><FONT COLOR=3D"#000000" SIZE=3D1 FAMILY=3D"SERIF" FACE=3D"Georgi= a" LANG=3D"0"><B>STEPHAN PICKERING / Chofetz Chayim ben-Avraham <BR>The Dinosaur Fractals Project <BR>2333 Portola Drive # 4 <BR>Santa Cruz, California 95062-4250 USA <BR>stephanpickering@cs.com <BR>website: http://groups.yahoo.com/group/paleo_bio_dinosaur_ontology <BR>theropod research summarized: <www.dinodata.net> see under PICKERI= NG at their Reference Base</B></FONT></HTML> --Boundary_(ID_ZJ7bwk/F/Q1997MX2Vq9ew)--