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The Botanical Review

, Volume 54, Issue 2, pp 107–128 | Cite as

Paraphyly, ancestors, and the goals of taxonomy: A botanical defense of cladism

  • Michael J. Donoghue
  • Philip D. Cantino
Article

Abstract

Cronquist (1987) criticizes cladism for its rejection of paraphyletic groups, which he would retain if he feels they are “conceptually useful.” We argue that paraphyletic higher taxa are artificial classes created by taxonomists who wish to emphasize particular characters or phenetic “gaps,” and that formal recognition of such taxa conveys a misleading picture of common ancestry and character evolution. In our view, classifications should accurately reflect the nested hierarchy of monophyletic groups that is the natural outcome of the evolutionary process. Such systems facilitate the study of evolution and provide an efficient summary of character distributions. Paraphyletic groups, such as “prokaryotes,” “green algae,” “bryophytes,” and “gymnosperms,” should be abandoned, as continued recognition of such groups will only serve to retard progress in understanding evolution. Contrary to Cronquist’s (1987) assertions, cladistic theory is not at odds with standard views on speciation and the existence of ancestors. Groups of interbreeding organisms can continue to exist after giving rise to descendant species, and there are several ways in which such groups, whether extant or extinct, can be incorporated into cladistic classification. In contrast, paraphyletic higher taxa are neither cohesive (integrated by gene flow) nor whole, do not serve as ancestors, and are unacceptable in the phylogenetic system. Fossils may be of great value in assessing phylogenetic relationships and are readily accommodated in cladistic classification. Cladistic studies are helping to answer major questions about plant evolution, and we anticipate increased efforts to develop a truly phylogenetic system.

Keywords

Green Alga Botanical Review Monophyletic Group Common Ancestry Cladistic Analysis 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Résumé

Cronquist (1987) critique le cladisme pour son rejet des groupes paraphylétiques, qu’il voudrait conserver quand ceux-ci sont “conceptuellement utiles.” Nous avançons l’argument que les taxons supérieurs paraphylétiques sont des groupes artificiels, définis par des taxonomistes qui désirent souligner certains caractères ou certaines “lacunes” phénétiques, et que la reconnaissance formelle de tels groupes donne une fausse impression de descendance commune et sur l’évolution de caractères. À notre avis, une classification doit refléter fidèlement la hiérarchie des groupes monophylétiques emboités, le résultat naturel du processus de l’évolution. Ces classifications facilitent l’étude de l’évolution et fournissent d’efficaces sommaires de la distribution phylétiques des caractères. La reconnaissance des groupes paraphylétiques, tels les “Prokaryotes,” les “Algues vertes,” les “Bryophytes,” et les “Gymnospermes,” devrait etre abandonnée, car elle ne peut que retarder notre compréhension de l’évolution. Contrairement à ce que Cronquist suggère, l’analyse cladistique n’est pas en désaccord avec les vues classiques sur la spéciation et l’existence d’ancêtres. Les groupes d’individus unifiés par le flux génétique peuvent continuer à exister après avoir donné souche à une nouvelle espèce, et il y a plusieurs moyens d’incorpores de tels groupes, qu’ils soient actuels ou disparus, dans une classification cladistique. Par contre, les taxons supérieurs paraphylétiques ne sont ni cohésifs (unifiés par le flux génétique) ou entiers, ne peuvent pas servir d’ancêtres, et sont inacceptables dans un systeme phylogénétique. Les fossiles peuvent être très utiles pour évaluer les rapports phylogénétique, et sont aisément incorporés dans une classification cladistique. Les analyses cladistiques contribuent à la solution de questions majeures de l’évolution des plantes, et nous prévoyons des efforts renouvelés pour le développement d’un systême réellement phylogénétique.

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Literature Cited

  1. Burger-Wiersma, T., M. Veenhuis, H. J. Korthals, C. C. M. Van de Wiel &L. R. Mur. 1986. A new prokaryote containing chlorophylls a and b. Nature320: 262–264.CrossRefGoogle Scholar
  2. —.Cantino, P. D. 1982. Affinities of the Lamiales: A cladistic analysis. Syst. Bot.7: 237–248.CrossRefGoogle Scholar
  3. —. 1985. Phylogenetic inference from nonuniversal derived character states. Syst. Bot.10: 119–122.Google Scholar
  4. — &R. W. Sanders. 1986. Subfamilial classification of Labiatae. Syst. Bot.11: 163–185.CrossRefGoogle Scholar
  5. Cracraft, J. 1983. Species concepts and speciation analysis. Curr. Ornithol.1: 159–187.Google Scholar
  6. Crane, P. R. 1985. Phylogenetic analysis of seed plants and the origin of angiosperms. Ann. Missouri Bot. Gard.72: 716–793.CrossRefGoogle Scholar
  7. Cronquist, A. 1987. A botanical critique of cladism. Bot. Rev.53: 1–52.CrossRefGoogle Scholar
  8. Dahlgren, R. &F. N. Rasmussen. 1983. Monocot evolution: Characters and phylogenetic estimation. Evol. Biol.16: 255–395.Google Scholar
  9. de Queiroz, K. 1988. Systematics and the Darwinian revolution. Philosophy of Science55(2) (in press).Google Scholar
  10. Donoghue, M. J. 1983. The phylogenetic relationships ofViburnum. Pages 143–166in N. I. Platnick & V. A. Funk (eds.), Advances in cladistics. Vol. 2. Columbia University Press, New York.Google Scholar
  11. —. 1985a. Pollen diversity and exine evolution inViburnum and the Caprifoliaceae sensu lato. J. Arnold Arb.66: 421–169.Google Scholar
  12. —. 1985b. A critique of the biological species concept and recommendations for a phylogenetic alternative. Bryologist88: 172–181.CrossRefGoogle Scholar
  13. — &P. D. Cantino. 1984. The logic and limitations of the outgroup substitution approach to cladistic analysis. Syst. Bot. 9: 192–202.CrossRefGoogle Scholar
  14. — &W. P. Maddison. 1986. Polarity assessment in phylogenetic systematics: A response to Meacham. Taxon35: 534–538.CrossRefGoogle Scholar
  15. Doyle, J. A. &M. J. Donoghue. 1986. Seed plant phylogeny and the origin of angiosperms: An experimental cladistic approach. Bot. Rev.52: 321–431.CrossRefGoogle Scholar
  16. — &M. J. Donoghue. 1987. The importance of fossils in elucidating seed plant phylogeny and macroevolution. Rev. Paleobot. Palyn.50: 63–95.CrossRefGoogle Scholar
  17. Dupuis, C. 1984. Willi Hennig’s impact on taxonomic thought. Ann. Rev. Ecol. Syst.15: 1–24.Google Scholar
  18. Eldredge, N. &J. Cracraft. 1980. Phylogenetic patterns and the evolutionary process. Columbia University Press, New York.Google Scholar
  19. Farris, J. S. 1979. The information content of the phylogenetic system. Syst. Zool.28: 483–519.CrossRefGoogle Scholar
  20. Gauthier, J. 1986. Saurischian monophyly and the origin of birds. Pages 1–55in K. Padian (ed.), The origin of birds and the evolution of flight. Mem. California Acad. Sci. No. 8.Google Scholar
  21. -,A. G. Kluge & T. Rowe. 1988. Amniote phylogeny and the importance of fossils. Cladistics. Vol. 4, No. 2 (in press).Google Scholar
  22. Graham, L. E. 1985. The origin of the life cycle of land plants. Amer. Sci.73: 178–186.Google Scholar
  23. Griffiths, G. C. D. 1974. On the foundations of biological systematics. Acta Biotheor.23: 85–131.CrossRefGoogle Scholar
  24. Hennig, W. 1966. Phylogenetic systematics. University of Illinois Press, Urbana.Google Scholar
  25. Hull, D. L. 1964. The effect of essentialism on taxonomy—Two thousand years of stasis (I). Brit. J. Philos. Sci.15: 314–326.Google Scholar
  26. —. 1965. The effect of essentialism on taxonomy—Two thousands years of stasis (II). Brit. J. Philos. Sci.16: 1–18.CrossRefGoogle Scholar
  27. —. 1979. The limits of cladism. Syst. Zool. 28:416–440.CrossRefGoogle Scholar
  28. Jansen, R. K. &J. D. Palmer. 1987. A chloroplast DNA inversion marks an ancient evolutionary split in the sunflower family (Asteraceae). Proc. Natl. Acad. Sci. 84: 5818–5822.PubMedCrossRefGoogle Scholar
  29. Lake, J. A. 1986. In defence of bacterial phylogeny. Nature321: 657–658.CrossRefGoogle Scholar
  30. Lewin, R. A. 1976. Prochlorophyta as a proposed new division of algae. Nature261: 697–698.PubMedCrossRefGoogle Scholar
  31. Maddison, W. P., M. J. Donoghue &D. R. Maddison. 1984. Outgroup analysis and parsimony. Syst. Zool.33: 83–103.CrossRefGoogle Scholar
  32. Margulis, L. 1981. Symbiosis in cell evolution. W. H. Freeman & Co., San Francisco.Google Scholar
  33. Mattox, K. R. &K. D. Stewart. 1984. Classification of the green algae: A concept based on comparative cytology. Pages 29–72in D. E. G. Irvine & D. M. John (eds.), Systematics of the green algae. Academic Press, London.Google Scholar
  34. Meacham, C. A. &T. Duncan. 1987. The necessity of convex groups in biological classification. Syst. Bot. 12: 78–90.CrossRefGoogle Scholar
  35. Michener, C. D. 1978. Dr. Nelson on taxonomic methods. Syst. Zool. 27: 112–128.CrossRefGoogle Scholar
  36. Mishler, B. D. &S. P. Churchill. 1985. Transition to a land flora: Phylogenetic relationships of the green algae and bryophytes. Cladistics1: 305–328.CrossRefGoogle Scholar
  37. — &M. J. Donoghue. 1982. Species concepts: A case for pluralism. Syst. Zool.31: 491–503.CrossRefGoogle Scholar
  38. Nelson, G. &N. Platnick. 1981. Systematics and biogeography: Cladistics and vicariance. Columbia University Press, New York.Google Scholar
  39. Pace, N. R., G. J. Olsen &C. R. Woese. 1986. Ribosomal RNA phylogeny and the primary lines of descent. Cell 45: 325–326.PubMedCrossRefGoogle Scholar
  40. Patterson, C. 1982. Morphological characters and homology. Pages 21–74in K. Joysey & A. Friday (eds.), Problems of phylogenetic reconstruction. Academic Press, New York.Google Scholar
  41. Pickett-Heaps, J. D. 1979. Electron microscopy and the phylogeny of green algae and land plants. Amer. Zool.19: 545–554.Google Scholar
  42. Platnick, N. 1979. Philosophy and the transformation of cladistics. Syst. Zool.28: 537–546.CrossRefGoogle Scholar
  43. Ridley, M. 1986. Evolution and classification. The reformation of cladism. Longman, New York.Google Scholar
  44. Sluiman, H. J. 1985. A cladistic evaluation of the lower and higher green plants (Viridiplantae). Pl Syst. Evol.149: 217–232.CrossRefGoogle Scholar
  45. Sneath, P. H. A. & R. R. Sokal. 1973. Numerical taxonomy. W. H. Freeman & Co., San Francisco.Google Scholar
  46. Stevens, P. F. 1984. Metaphors and typology in the development of botanical systematics 1690–1960, or the art of putting new wine in old bottles. Taxon33: 169–211.CrossRefGoogle Scholar
  47. —. 1986. Evolutionary classification in botany, 1960–1985. J. Arnold Arbor.67: 313–339.Google Scholar
  48. Stewart, K. D. &K. R. Mattox. 1975. Comparative cytology, evolution and classification of the green algae with some consideration of the origin of other organisms with chlorophyllsa andb. Bot. Rev.41: 104–135.CrossRefGoogle Scholar
  49. Sytsma, K. J. &L. D. Gottlieb. 1986. Chloroplast DNA evidence for the derivation of the genusHeterogaura from a species ofClarkia (Onagraceae). Proc. Natl. Acad. Sci. 83: 5554–5557.PubMedCrossRefGoogle Scholar
  50. Wiley, E. O. 1981. Phylogenetics: The theory and practice of phylogenetic systematics. John Wiley & Sons, New York.Google Scholar
  51. Woese, C. R. &G. E. Fox. 1977. Phylogenetic structure of the prokaryotic domain: The primary kingdoms. Proc. Natl. Acad. Sci. 74: 5088–5090.PubMedCrossRefGoogle Scholar
  52. Wolters, J. &V. A. Erdmann. 1986. Cladistic analysis of 5S rRNA and 16S rRNA secondary and primary structure—The evolution of eukaryotes and their relation to archaebacteria. J. Molec. Evol.24: 152–166.CrossRefGoogle Scholar

Copyright information

© The New York Botanical Garden 1988

Authors and Affiliations

  • Michael J. Donoghue
    • 1
  • Philip D. Cantino
    • 2
  1. 1.Department of Ecology and Evolutionary BiologyUniversity of ArizonaTucsonUSA
  2. 2.Department of BotanyOhio UniversityAthensUSA

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