From Plant Press, Vol. 4, No. 2 from April 2001.
By Robert DeFilipps
Once you start assuming that the disciplines of “Taxonomy” and ”Cladistics” are in a state of peaceful coexistence, you will probably encounter their fusion product, the gremlins of “Science Friction.” They exhibit a certain amount of hybrid vigor. Gremlin Number 1 might ask herbarium curators to consolidate, and then re-file alphabetically by genus, all their specimens of Cactaceae and Portulacaceae into a single family, in keeping with precepts of current evolutionary thought. Gremlin Number 2 might seek out individuals obsessed with plant identification, and suggest the prospect of finding uninomial clade names on annotation labels. A recent symposium in Washington, D.C. provided botanists and zoologists a major opportunity to dispel mythologies and bring a wide variety of opinions to a forum where the relations of taxonomy and cladistics could be fully explored.
The first Smithsonian Botanical Symposium, on “Linnaean Taxonomy in the 21st Century,” was convened at the National Museum of Natural History, 30-31 March 2001. After introductory remarks by Scott Miller, Chairman of the Department of Systematic Biology, the approximately 260 attendees were welcomed by W. John Kress, Head of Botany, who proceeded to award the Cuatrecasas Medal for Excellence in Tropical Botany to Rogers McVaugh. The deeply moved audience rose to a standing ovation for the accomplishments of this senior specialist of Myrtaceae, Rosaceae and the Mexican flora (see related article, page 7).
It was then time to begin an all-day examination of standard Linnaean taxonomy in the milieu of increasingly pro-active phylogenetic considerations. One of the several Byzantine books on exhibit at the symposium, a 1483 Latin copy of “De Historia Plantarum” by Theophrastus (fl. 400-300 B.C.), served to transport us back to a time when plants were divided into four categories: trees, shrubs, subshrubs and herbs. Theophrastus must have truly believed “less is more.” To provide a historical framework including the 18th century work of Carl Linnaeus, Dan H. Nicolson (Smithsonian Institution) presented the first paper, entitled “Stone, Plant, or Animal?” Linnaeus inclusively treated the known natural world, and placed “animals” at the apex of a three-level pyramid of existence, with “vegetables” (plants) below animals, and “stones” (Lapidum) at rock bottom. The Swedish sage employed four levels of classification: class, order, genus, species: no families, and his prescient generic description of genus Homo was “You know yourself.” Linnaeus’ utilization of binomial (binary) nomenclature has been retained into modern times, although his curious “Sexual System” was later abandoned. Nicolson urged the audience to remember, for purposes of differentiating taxonomy and systematics, that your name is not the same as who you are.
Richard K. Brummitt (Royal Botanic Gardens, Kew), who is currently involved with the Species Plantarum Project, presented “How to Chop Up a Tree,” which accorded a major role to paraphyletic taxa in the conduct of modern taxonomy. He ventured support for opinions that taxonomic systems and evolutionary schemes are separate and incompatible; that every taxon makes another taxon paraphyletic; and that cladistics is a “counterintuitive” exercise in “futile mental gymnastics” while “the pursuit of monophyly has become an obsession.” Brummitt’s final plea was for taxonomists to avoid hopelessly confusing taxonomy (classification) with evolutionary phylogenetic schemes.
The third speaker, Paul E. Berry (University of Wisconsin), delivered an illustrated address on the subject of “Practical Implications of Changing Classification Schemes for Floristic and Inventory Studies, and Is Anybody Thinking About the General Public?” Central to his theme that “species are the basic phylogenetic currency,” Berry considered the PhyloCode (an alternative code of nomenclature based on cladistics) to be a “smokescreen” that would hinder further floristic work, especially in the tropics. His expectation was that the PhyloCode will be “absorbed into the amoeba of culture.” Berry pointed out the transience of current phylogenetic studies, and hence phylogenetic nomenclature, with the example of the Saxifoliaceae, comprising Saxifolium from Venezuelan Guayana, that is no longer considered an endemic family but now assigned to Gentianaceae as a result of successive DNA analyses. Numerous hypothetical questions abounded, such as whether a species of orchid (representing a rapidly speciating family) is the equivalent of a species of tree.
The afternoon session began with Brent Mishler (University of California, Berkeley). An energetic spokesperson for cladistics, he radiated the impression that botanists not well versed in Hennigian philosophy might get shredded if they fly in his path. Mishler’s lecture, entitled “Rank-Free Phylogenetic Classification and the Unification of Biology,” was built on the premise that any classification is a snapshot of organisms imposed on nature at a certain point in time. Mishler is striving for a uniform view of biodiversity and then arriving at a phylogenetically-based classification that adequately portrays evolution.
Peter Forey (paleontologist at The Natural History Museum, London), in a presentation titled “PhyloCode – Pain But No Gain,” seemed to imply that the PhyloCode has certain shortcomings, not the least of which may be a lack of empirical content. Forey dissected the PhyloCode from a Linnaean taxonomic perspective and demonstrated the difficulties and inconsistencies of making such a system work. One such example was research by his colleague Sandra Knapp (BM), who cladistically ascertained that the common tomato (Lycopersicon) is (by inference of nested clades) a member of the potato genus (Solanum), which would have significant commercial implications if classified according to the PhyloCode.
The final speaker was Peter Stevens (Missouri Botanical Garden, St. Louis), who applied himself to an exposition of “the rhetoric of species manufacture” by those challenging the Linnaean system, in which the “good guys (cladists) discover species and the bad guys (Linnaeans) create species.” He prescribed a concise and philosophical perspective on the history of classification from Linnaeus to Bentham.
After the lecture session, Vicki A. Funk (Smithsonian Institution) led a discussion in which one of the respondees was also a major figure in the study of cladistics and the originator of the PhyloCode, Kevin de Queiroz (Smithsonian Institution); the latter observed that if a person is grappling with a difficult specimen of uncertain, they have the option to make a new uninomial species which can be assigned to a clade, and thus they would not have to assign it to a genus or higher rank.
Everyone carried from the lecture sessions their own conclusions as to the widening role of phylogeny in our attempts to classify organisms, with or without hierarchical systems. Certainly it served to increase everyone’s vocabulary of current botanical insights. The critical factor of acceptability of opinions might be summarized by a quotation that emanates from an unexpected source, a piece by George Steiner (The New Yorker 64(11):116. 2 May 1988) about the controversial English novelist John Cowper Powys, as follows: “Non disputandum, says the Latin tag. Matters of taste are not to be quarreled over…No psychology in depth, no aesthetic theorizing, no appeal to authority can settle the argument either way. The mechanics of affinity or distance can be modified: schools, critical judgments by those whom we take to be in authority, the voice of our community and culture do shape our responses. But only so far. At bottom lies the mystery of intuition.”
At the conclusion of the discussions, it was announced that the Hunt Institute for Botanical Documentation and the National Museum of Natural History will co-sponsor a hands-on workshop next winter to bring together representatives from both sides of the debate. The goal will be to formulate a workable system of nomenclature and classification that incorporates evolutionary and phylogenetic information without overturning all that has worked since Linnaeus established his system 250 years ago.
After the symposium dinner, the Keynote speaker took to the lectern. Professor Edward O. Wilson (Museum of Comparative Zoology, Harvard University), who addressed “The Future of Life,” reminded us of the bewildering complexity of living things and the importance of systematists in understanding and documenting the natural world. As we strive to “complete the Linnaean enterprise” he suggested that this is not a good time in the face of devastating environmental perturbations and species extinctions to drastically alter the mode of nomenclature and classification, and especially to exhibit a bickering community of taxonomists whose job is the conservation and preservation of the world’s biodiversity.
Wilson recommended that systematists should focus their efforts on discovering life and understanding phylogenetic relationships. He stressed that for taxonomists to be considering a radical makeover of our method of classification at this time would be like “rewriting the operating manual for the Titanic.” Repercussions may occur when significant portions of human society will increasingly face an existence in degraded, severely impacted environments. In the long run, the ramifications of a great deal of biological research will impact upon our humanity, economy and world security.
Comments