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Critique of Pure Folly 79 CRITIQUE OF PURE FOLLY 79 The Botanical Review 69(1): 79–92 Critique of Pure Folly JAMES M. CARPENTER Division of Invertebrate Zoology American Museum of Natural History New York, NY 10024, U.S.A. I. Abstract . 79 II. Introduction . 79 III. Background . 80 A. Stability . 80 B. Ranks . 83 IV. The PhyloCode . 84 A. Preface . 85 B. Preamble . 85 C. Principles . 86 D. Rules . 86 1. Article 6 . 86 2. Article 9 . 87 3. Article 11 . 87 4. Article 15 . 90 5. Article 21 . 90 V. Conclusions . 91 VI. Acknowledgments . 91 VII. Literature Cited . 91 I. Abstract A critique of the draft PhyloCode is presented. Its stated goals cannot be met by the propos- als in the current draft, which also fails to uphold its stated principles. Its internal contradic- tions include a cumbersome reinvention of the very aspect of the current Linnaean system that advocates of the PhyloCode most often decry. II. Introduction Proposals to discard the current systems of biological nomenclature and replace them with a so-called phylogenetic taxonomy received considerable publicity for about a decade without any specific details on implementation of the replacement system (see Nixon & Carpenter, 2000). This lack of detail did not prevent—indeed, it doubtless aided—the favorable fanfare in the popular media (e.g., Pennisi, 1996, 2001; Chui, 1999; Milius, 1999; Fellman, 2000; Withgott, 2000). Finally, a draft of a “PhyloCode” has been promulgated on the World Wide Web at Copies of this issue [69(1)] may be purchased from the NYBG Press, The New York Botanical Garden, Bronx, NY 10458–5128, U.S.A.; [email protected]. Please inquire as to prices. Issued 00 June 2003 © 2003 The New York Botanical Garden 79 80 THE BOTANICAL REVIEW <http://www.ohiou.edu/phylocode/>. The release of the draft presents the opportunity, as the preface states, “to explore the ramifications of phylogenetic [sic] nomenclature.” The philo- sophical “foundation” of the PhyloCode has already been the subject of a thorough critique by Nixon and Carpenter (2000), who also showed that so-called phylogenetic nomenclature would be less stable than the existing systems. The response by advocates of the PhyloCode to that critique has been mere plays on words (viz., Lee, 2001; Bryant & Cantino, 2002); substantive counterargument is not likely to be forthcoming. Rather than a dissection of these specious responses here, the availability of the draft PhyloCode invites another kind of critique, a scru- tiny of the details of this attempt to provide “a precise, coherent, international system for naming” (Cantino & de Queiroz, 2000: preamble 1), which will obviate the necessity for any such rebuttal. III. Background A. STABILITY Some background will be useful. Since the inception of so-called phylogenetic taxonomy (de Queiroz & Gauthier, 1990, etc.), its advocates have claimed that the advantage of this approach would be greater taxonomic stability than current systems of nomenclature provide. Whereas the current Linnaean systems employ typification (to family-group level) and ranked taxa, the proposed “node-based” method of so-called phylogenetic taxonomy entails designat- ing two (or more) terminals subtended by a node of a cladogram and declaring that the name points to the common ancestor of those descendants and all other descendants of that ancestor. Arguments purporting to establish that this approach is more stable have emphasized changes in rank due to lumping and splitting in current nomenclature, and abolition of ranks has been proposed as a solution. I will return to the subject of ranks later, but here wish to stress that the crucial aspect of taxonomic stability is content. As developed by Nixon and Carpenter (2000), taxonomic stability is measured in terms of all taxa included in a group referred to by a particu- lar name; or, put another way, instability is measured by the number of included taxa that do not occur in each application of a particular name. A name is used in two different senses if it does not refer to the same set of taxa in two applications; that is instability, in taxonomy and in language. By contrast, if a name is used in one case, say, for a family, and another for a subfamily, but in each case circumscribes exactly the same included taxa, that is trivial for communicating the meaning—the content—of the name. Any experienced taxonomist under- stands this, but advocates of the PhyloCode completely fail to grasp this point. For example, Lee (1996: 188) approved of the fact that in so-called phylogenetic taxonomy “it is not the names of clades that change, but the contents of those named clades”; and Bryant and Cantino (2002: 53) concluded that the PhyloCode achieved “stability in the phylogenetic meaning of taxon names” despite conceding instability in terms of content, although they allowed that that was “a relevant issue.” This confusion between meaning and spelling persists in the draft PhyloCode. In fact, the stability claimed for the PhyloCode is purely metaphysical (Nixon & Carpenter, 2000), having nothing to do with real taxonomic stability; by Orwellian antilogic, its instability is proclaimed to be “stable.” Net change in content quantifies taxonomic instability: If two uses of a name circumscribe the same taxa, the net change is zero, and there is no instability. Nixon and Carpenter (2000) pre- sented examples showing that Linnaean classification outperforms or matches the stability of so- called phylogenetic taxonomy and that if a Linnaean classification is based on a type that is one of the “specifiers” of a “node-based” PhyloCode classification, it is always possible to maintain a classification at least as stable as, and usually more stable, than the PhyloCode classification. CRITIQUE OF PURE FOLLY 81 Fig. 1. Hypothetical cladogram (although most of the names are in fact available in the wasp family Vespidae; Carpenter & Day, 1988). Fig. 2. Alternative hypothetical cladogram, with the position of Alpha changed. Measuring net change in content also provides a basis for maximizing stability of estab- lished names when change is required, as for example when revising classification to remove paraphyly. This can be illustrated with an example, taken from a proponent of the PhyloCode, in which the consequences of nomenclatural changes in the so-called phylogenetic and Lin- naean system were compared—superficially. De Queiroz (1996: figs. 6, 8) presented a hypo- thetical example comparing changes in composition of taxa under both Linnaean and so-called phylogenetic classification to show that “both Linnaean and phylogenetic approaches can re- sult in changes in the hypothesized composition of taxa, that is, instability” (p. 15). Indeed, but it is generally less under the Linnaean system. The example is reprised in Figures 1 and 2, which show two different cladograms for the same group. The so-called phylogenetic and the Linnaean classifications presented by de Queiroz (1996) for each cladogram are given in Tables I and II. In this case the taxon changing position, Alpha, is a specifier (or pseudotype) in the so- called phylogenetic classification, and a type in the Linnaean classification. The consequences of its shift in position for the so-called phylogenetic classification are that Alphadeltina goes from encompassing four taxa to eight (4), Alphathetonia goes from encompassing eight taxa to 82 THE BOTANICAL REVIEW Table I Node-pointing classifications presented by de Queiroz (1996: fig. 6) for the cladograms in Figures 1 and 2. Alphathetonia is defined as the taxon stemming from the most recent common ancestor of Alpha and Theta; Alphadeltina, as the taxon stemming from the most recent common ancestor of Alpha and Delta; and Thetazina, as the taxon stemming from the most recent common ancestor of Theta and Zeta. Classification for Figure 1 Alphathetonia Alphadeltina Alpha Beta Delta Gamma Thetazina Epsilon Zeta Eta Theta Classification for Figure 2 Alphadeltina Beta Delta Gamma Alphathetonia Alpha Thetazina Epsilon Zeta Eta Theta five (3), and Thetazina undergoes no change (0), for a net total of seven (7) changes in content. For the Linnaean classification, de Queiroz (1996: 14) noted: “In this case, there are several possible nomenclatural outcomes, depending on which taxa are assigned to the family cat- egory. Let us just consider the ranking scheme that most closely approximates the situation that I described earlier for the phylogenetic [sic] definitions[;] . that is, the one in which all eight terminal taxa are considered to form a single family.” In that case the family Alphaceae replaces the suborder Alphineae and goes from referring to four taxa to eight (4), whereas Thetaceae does not change in composition, but merely in rank, to Thetoideae (0), for a net total of four (4) changes in content. Not only are the changes fewer, the change in rank endings actually conveys information on relative position in the hierarchy. I will discuss the subject of ranks below, but first wish to stress that the changes for the so-called phylogenetic classifica- tion are mandatory: Under a “node-based” system, when the named clade pointed to by one of the specifiers of that clade is discarded in favor of a differently circumscribed clade, whatever clade now pointed to by both specifiers adopts the name. The Linnaean system is more flex- ible, because only the taxon containing the single type must retain the name established with that type. So, for this example one of the possible nomenclatural outcomes not discussed by de Queiroz would be to retain the suborder Alphineae, retain the family Thetaceae, and restrict the family Alphaceae to Alpha (3), while creating a new family for Beta, Delta, and Gamma—a net change of 3 for the previously established names. An experienced taxonomist might well CRITIQUE OF PURE FOLLY 83 Table II Linnaean classifications presented by de Queiroz (1996: fig. 8) for the cladograms in Figures 1 and 2.
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