Disparity as an evolutionary index: a comparison of Cambrian and Recent arthropods | Paleobiology | Cambridge Core (original) (raw)

Abstract

Disparity is a measure of the range or significance of morphology in a given sample of organisms, as opposed to diversity, which is expressed in terms of the number (and sometimes ranking) of taxa. At present there is no agreed definition of disparity, much less any consensus on how to measure it. Two possible categories of metric are considered here, one independent of any hypothesis of relationship (phenetics), the other constrained within an evolutionary framework (cladistics).

The Early Cambrian radiation was clearly a period of significant morphologic and taxonomic diversification. However, we question the interpretation of its first generation products as numerous body plans at the highest level. Four phenetic and two cladistic measures have been used to compare disparity among Cambrian arthropods with that in the living fauna. Phenetic methods assessing character-state variability and the amount of morphological attribute space occupied yield similar results for Cambrian and Recent arthropods. Assessments of disparity within a taxonomic framework rely on the identification of particular characters that delineate higher level body plans. This requires a phylogenetic interpretation, a cladistic investigation of hierarchical structure in the data. Both sets of arthropods fall within the same major clades, and within this cladistic framework the amount of character-state evolution in the two groups is comparable. None of these methods identifies markedly greater disparity among the Cambrian compared with the Recent taxa.

Although measures of disparity are applied here to a consideration of the Cambrian radiation, the metrics clearly have a much wider potential for estimating macroevolutionary trends independently from existing taxonomic frameworks. Geometric morphometry is ideal for measuring morphological variety at lower taxonomic levels, but it requires the recognition of homologous landmarks in all the forms under comparison, or the identification of entire homologous structures. Conventional phenetics has much wider application as it can operate on data coded as discrete homologous character states (this facility is also a requirement of cladistics), which are a more appropriate basis for comparing disparity in markedly dissimilar forms.

References

Anderson, D. T. 1973. Embryology and phylogeny of the annelids and arthropods. Pergamon, Oxford.Google Scholar

Archie, J. W. 1989a. A randomization test for phylogenetic information in systematic data. Systematic Zoology 38:239–252.CrossRefGoogle Scholar

Archie, J. W. 1989b. Homoplasy excess ratios: new indices for measuring levels of homoplasy in systematics and a critique of the consistency index. Systematic Zoology 38:253–269.CrossRefGoogle Scholar

Archie, J. W. 1989c. Phylogenies of plant families: a demonstration of phylogenetic randomness in DNA sequence data derived from proteins. Systematic Zoology 38:239–252.CrossRefGoogle Scholar

Ballard, J. W. O., Olsen, G. J., Faith, D. P., Odgers, W. A., Rowell, D. M., and Atkinson, P. W. 1992. Evidence from 12S ribosomal RNA that onychophorans are modified arthropods. Science 258:1345–1348.CrossRefGoogle ScholarPubMed

Bergström, J. 1976. Early arthropod morphology and relationships. , p. 289.Google Scholar

Bergström, J. 1979. Morphology of fossil arthropods as a guide to phylogenetic relationships. Arthropod phylogeny. Pp. 3–56_in_ Gupta, .Google Scholar

Bergström, J. 1981. Morphology and systematics of early arthropods. Abhandlungen des Naturwissenschaftlichen Vereins in Hamburg 23:7–42.Google Scholar

Bergström, J. 1992. The oldest arthropods and the origin of the Crustacea. Acta Zoologica 73:287–291.CrossRefGoogle Scholar

Bookstein, F. L., Chernoff, B., Elder, R. L., Humphries, J. M., Smith, G. R., and Strauss, R. E. 1985. Morphometrics in evolutionary biology. Academy of Natural Sciences, Philadelphia, .Google Scholar

Boudreaux, H. B. 1979a. Significance of intersegmental tendon systems in arthropod phylogeny, and a monophyletic classification of the Arthropoda. Pp. 551–586_in_ Gupta, .Google Scholar

Boudreaux, H. B. 1979b. Arthropod phylogeny, with special reference to insects. Wiley, New York.Google Scholar

Briggs, D. E. G. 1981. The arthropod Odaraia alata Walcott, Middle Cambrian, Burgess Shale, British Columbia. Transactions of the Royal Society, London B 291:541–585.Google Scholar

Briggs, D. E. G. 1983. Affinities and early evolution of the Crustacea: the evidence of the Cambrian fossils. Pp. 1–22_in_ Schram, F. R., ed. Crustacean phylogeny. Balkema, Rotterdam.Google Scholar

Briggs, D. E. G. 1990. Early arthropods: dampening the Cambrian explosion. Pp. 24–43_in_ Culver, S. J., ed. Arthropod paleobiology. . Paleontological Society, Knoxville, Tenn.Google Scholar

Briggs, D. E. G., and Collins, D. 1988. A Middle Cambrian chelicerate from Mount Stephen, British Columbia. Paleontology 31:71–73.Google Scholar

Briggs, D. E. G., and Fortey, R. A. 1989. The early radiation and relationships of the major arthropod groups. Science 246:241–243.CrossRefGoogle ScholarPubMed

Briggs, D. E. G., and Whittington, H. B. 1981. Relationships of arthropods from the Burgess Shale and other Cambrian sequences. Pp. 38–41_in_ Taylor, M. E., ed. Short papers for the Second International Symposium on the Cambrian System. U.S. Geological Survey, .Google Scholar

Briggs, D. E. G., and Whittington, H. B. 1985. The mode of life of the Burgess Shale arthropods. Transactions of the Royal Society of Edinburgh; Earth Sciences 76:149–160.CrossRefGoogle Scholar

Briggs, D. E. G., Fortey, R. A., and Wills, M. A. 1992a. Morphological disparity in the Cambrian. Science 256:1670–1673.CrossRefGoogle ScholarPubMed

Briggs, D. E. G., Fortey, R. A., and Wills, M. A. 1992b. Cambrian and Recent morphological disparity. (Response to Foote and Gould, and Lee). Science 258:1817–1818.CrossRefGoogle Scholar

Briggs, D. E. G., Fortey, R. A., and Wills, M. A. 1993. How big was the Cambrian explosion? A taxonomic and morphologic comparison of Cambrian and Recent arthropods. Pp. 33–44_in_ Lees, D. R. and Edwards, D., eds. Evolutionary patterns and processes. . Linnean Society of London.Google Scholar

Brusca, R. C., and Brusca, G. J. 1990. Invertebrates. Sinauer, Mass.Google Scholar

Bruton, D. L., and Whittington, H. B. 1983. Emeraldella and Leanchoilia, two arthropods from the Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society, London B 300:553–585.Google Scholar

Butterfield, N. J. 1990. A reassessment of the enigmatic Burgess Shale fossil Wiwaxia corrugata (Matthew) and its relationship to the polychaete Canadia spinosa Walcott. Paleobiology 16:287–303.CrossRefGoogle Scholar

Calman, W. T. 1909. Crustacea. Pp. 1–346_in_ Lankester, R., ed. Treatise on zoology VII (Appendiculata) (Fascicule 3). Adam & Black, London.Google Scholar

Cherry, L. M., Case, S. M., Kunkel, J. G., Wyles, J. S., and Wilson, A. C. 1982. Body shape metrics and organismal evolution. Evolution 35:914–933.CrossRefGoogle Scholar

Conway Morris, S. 1985. The Middle Cambrian metazoan Wiwaxia corrugata (Matthew) from the Burgess Shale and Ogygopsis Shale, British Columbia, Canada. Philosophical Transactions of the Royal Society of London B 307:507–586.Google Scholar

Conway Morris, S. 1986. The community structure of the Middle Cambrian phyllopod bed (Burgess Shale). Palaeontology 29:423–467.Google Scholar

Conway Morris, S. 1992. Burgess Shale-type faunas in the context of the “Cambrian explosion”: a review. Journal of the Geological Society of London 149:631–636.CrossRefGoogle Scholar

Donoghue, M. J., Doyle, J. A., Gauthier, J., Kluge, A. G., and Rowe, T. 1989. The importance of fossils in phylogeny reconstruction. Annual Review of Ecology and Systematics 20:431–460.CrossRefGoogle Scholar

Dunn, G., and Everitt, B. S. 1982. An introduction to mathematical taxonomy. Cambridge University Press, Cambridge.Google Scholar

Efron, B. 1982. The jackknife, the bootstrap, and other resampling plans. Society for Industrial and Applied Mathematics, Philadelphia.CrossRefGoogle Scholar

Eldredge, N., and Cracraft, J. 1980. Phylogenetic patterns and the evolutionary process. Columbia University Press, New York.Google Scholar

Erwin, D. H. 1990. Carboniferous–Triassic gastropod diversity patterns and the Permo-Triassic mass extinction. Paleobiology 16:187–203.CrossRefGoogle Scholar

Erwin, D. H. 1992. A preliminary classification of evolutionary radiations. Historical Biology 6:133–147.CrossRefGoogle Scholar

Faith, D. P., and Cranston, P. S. 1991. Could a cladogram this short have arisen by chance alone? On permutation tests for cladistic structure. Cladistics 7:1–28.CrossRefGoogle Scholar

Field, K. G., Olsen, G. J., Lane, D. J., Giovannoni, S. J., Ghiselin, M. T., Raff, E. C., Pace, N. R., and Raff, R. A. 1988. Molecular phylogeny of the animal kingdom. Science 239:748–753.CrossRefGoogle ScholarPubMed

Foote, M. 1989. Perimeter-based Fourier analysis: a new morphometric method applied to the trilobite cranidium. Journal of Paleontology 63:880–885.CrossRefGoogle Scholar

Foote, M. 1990. Nearest-neighbor analysis of trilobite morphospace. Systematic Zoology 39:371–382.CrossRefGoogle Scholar

Foote, M. 1991a. Morphologic patterns of diversification: examples from trilobites. Palaeontology 34:461–485.Google Scholar

Foote, M. 1991b. Morphological and taxonomic diversity in a clade's history: the blastoid record and stochastic simulations. Contributions from the Museum of Paleontology, the University of Michigan 28:101–140.. Cambrian Printers, Aberystwyth.Google Scholar

Kruskal, J. B. 1964a. Multidimensional scaling by optimizing goodness of fit to a nonmetric hypothesis. Psychometrica 29:1–27.CrossRefGoogle Scholar

Kruskal, J. B. 1964b. Nonmetric multidimensional scaling: a numerical method. Psychometrica 29:1–27.CrossRefGoogle Scholar

McMenamin, M. A. S., and McMenamin, D. L. S. 1990. The emergence of animals, the Cambrian breakthrough. Columbia University Press, New York.CrossRefGoogle Scholar

Patterson, C., and Rosen, D. E. 1977. Review of ichthyodectiform and other Mesozoic teleost fishes and the theory and practice of classifying fossils. Bulletin of the American Museum of Natural History 158:81–172.Google Scholar

Pielou, E. C. 1975. Ecological diversity. Wiley, New York.Google Scholar

Pimentel, R. A., and Riggins, R. 1987. The nature of cladistic data. Cladistics 3:201–209.CrossRefGoogle Scholar

Ramsköld, L., and Edgecombe, G. D. 1991. Trilobite monophyly revisited. Historical Biology 4:267–283.CrossRefGoogle Scholar

Raup, D. M., and Gould, S. J. 1974. Stochastic simulation and evolution of morphology—towards a nonmothetic paleontology. Systematic Zoology 23:305–322.CrossRefGoogle Scholar

Ridley, M. 1990. Dreadful beasts. The London Review of Books, June 28:11–12.Google Scholar

Riedl, R. 1978. Order in living organisms. Wiley, New York.Google Scholar

Rohlf, F. J. 1973. Algorithm 76. Hierarchical clustering using the minimum spanning tree. Computer Journal 16:93–95.Google Scholar

Rohlf, F. J., and Sokal, R. R. 1965. Coefficients of correlation and distance in numerical taxonomy. University of Kansas Scientific Bulletin 45:3–27.Google Scholar

Runnegar, B. 1987. Rates and modes of evolution in the Mollusca. Pp. 39–60_in_ Campbell, K. S. W. and Day, M. F., eds. Rates of evolution. Allen and Unwin, London.Google Scholar

Saunders, W. B., and Swan, A. R. H. 1984. Morphology and morphologic diversity of mid-Carboniferous (Namurian) ammonoids in time and space. Paleobiology 10:195–228.CrossRefGoogle Scholar

Schank, J. C., and Wimsatt, W. C. 1986. Generative entrenchment and evolution. Philosophy of Science Association 2:33–60.Google Scholar

Schram, F. R. 1978. Arthropods: a convergent phenomenon. Fieldiana: Geology 39:61–108.Google Scholar

Sepkoski, J. J. Jr., and Kendrick, D. C. 1993. Numerical experiments with model monophyletic and paraphyletic taxa. Paleobiology 19:168–184.CrossRefGoogle ScholarPubMed

Sharov, A. G. 1966. Basic arthropodan stock. Pergamon, New York.Google Scholar

Shepard, R. N. 1962. The analysis of proximities: multidimensional scaling with an unknown distance function, I and II. Psychometrika 27:125–140, .CrossRefGoogle Scholar

Shepard, R. N. 1966. Metric structures in oridinal data. Journal of Mathematical Psychology 3:287–315.CrossRefGoogle Scholar

Shergold, J. H. 1991. Protaspid and early meraspid growth stages of the eodiscoid trilobite Pagetia ocellata Jell, and their implications for classification. Alcheringa 15:65–86.CrossRefGoogle Scholar

Simonetta, A., and Delle Cave, L. 1975. The Cambrian non trilobite arthropods from the Burgess Shale of British Columbia. A study of their comparative morphology, taxonomy and evolutionary significance. Palaeontographica Italica 69:1–37.Google Scholar

Smith, A. B. 1994. Systematics and the fossil record: documenting evolutionary patterns. Blackwell Scientific, Boston.CrossRefGoogle Scholar

Sneath, P. H. A. 1962. The construction of taxonomic groups. Pp. 289–332_in_ Ainsworth, G. C. and Sneath, P. H. A., eds. Microbial classification. . Cambridge University Press.Google Scholar

Sneath, P. H. A., and Sokal, R. R. 1973. Numerical taxonomy. W. H. Freeman, San Francisco.Google Scholar

Snodgrass, R. E. 1938. The evolution of the Annelida, Onychophora and Arthropoda. Smithsonian Miscellaneous Collections 97:1–59.Google Scholar

Snodgrass, R. E. 1950. Comparative studies of the jaws of mandibulate arthropods. Smithsonian Miscellaneous Collections 116:1–85.Google Scholar

Snodgrass, R. E. 1956. Crustacean metamorphosis. Smithsonian Miscellaneous Collections 131:1–78.Google Scholar

Snodgrass, R. E. 1958. Evolution of arthropod mechanisms. Smithsonian Miscellaneous Collections 138:1–77.Google Scholar

Sokal, R. R. 1961. Distance as a measure of taxonomic similarity. Systematic Zoology 10:70–79.CrossRefGoogle Scholar

Sokal, R. R., and Michener, C. D. 1958. A statistical method for evaluating systematic relationships. University of Kansas Scientific Bulletin 38:1409–1438.Google Scholar

Sokal, R. R., and Sneath, P. H. A. 1963. Princples of numerical taxonomy. W. H. Freeman, San Francisco.Google Scholar

Størmer, L. 1944. On the relationships and phylogeny of fossil and Recent Arachnomorpha. Skrifter utgitt av det Norske Vidensk Academi i Oslo 5:1–158.Google Scholar

Stanley, S. M. 1979. Macroevolution: pattern and process. W. H. Freeman, San Francisco.Google Scholar

Stubblefield, C. J. 1960. Evolution in trilobites. Quarterly Journal of the Zoological Society of London 115:145–162.Google Scholar

Swofford, D. L. 1990. PAUP: phylogenetic analysis using parsimony, version 3.0. Computer program distributed by the Illinois Natural History Survey, Champaign, Illinois.Google Scholar

Temple, J. T. 1980. A numerical taxonomic study of the Trinucleidae (Trilobita) from the British Isles. Transactions of the Royal Society of Edinburgh 71:213–233.CrossRefGoogle Scholar

Temple, J. T. 1982. Ordination of palaeontological data. Miscellaneous Papers of the Geological Society of London 14:224–236.Google Scholar

Temple, J. T., and Tripp, R. P. 1979. An investigation of the Encrinurinae (Trilobita) by numerical taxonomic methods. Transactions of the Royal Society of Edinburgh 70:223–250.CrossRefGoogle Scholar

Temple, J. T., and Wu, H.-J. 1990. Numerical taxonomy of Encrinurinae (Trilobita): additional species from China and elsewhere. Transactions of the Royal Society of Edinburgh 81:209–219.CrossRefGoogle Scholar

Turbeville, J. M., Pfeifer, D. M., Field, K. G., and Raff, R. A. 1991. The phylogenetic status of arthropods, as inferred from 18S RNA sequences. Journal of Molecular Evolution 8:669–686.Google Scholar

Valentine, J. W. 1969. Patterns of taxonomic and ecological structure of the shelf benthos during Phanerozoic time. Palaeontology 12:684–709.Google Scholar

Valentine, J. W. 1977. General patterns in Metazoan evolution. Pp. 27–57_in_ Hallam, A., ed. Patterns of evolution as illustrated by the fossil record. Elsevier Scientific, Oxford.CrossRefGoogle Scholar

Valentine, J. W. 1989. Bilaterians of the Precambrian-Cambrian transition and the annelid-arthropod relationship. Proceedings of the National Academy of Sciences, USA. 86:2272–2275.CrossRefGoogle ScholarPubMed

Van Valen, L. 1974. Multivariate structural statistics in natural history. Journal of Theoretical Biology 45:235–247.CrossRefGoogle ScholarPubMed

Walcott, C. D. 1908. Mount Stephen rocks and fossils. Canadian Alpine Journal 1:232–248.Google Scholar

Walcott, C. D. 1911. Middle Cambrian Merostomata. Cambrian geology and palaeontology, II. Smithsonian Miscellaneous Collections 57:17–40.Google Scholar

Walcott, C. D. 1912. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Cambrian geology and palaeontology, II. Smithsonian Miscellaneous Collections 57:109–144.Google Scholar

Weygoldt, P. 1979. Significance of later embryonic stages and head development in arthropod phylogeny. Pp. 107–135_in_ Gupta, .Google Scholar

Whittington, H. B. 1985. The Burgess Shale. Yale University Press, New Haven.Google Scholar

Wiley, E. O. 1981. Phylogenetics: the theory and practice of phylogenetic systematics. Wiley, New York.Google Scholar

Wimsatt, W. C., and Schank, J. C. 1988. Two constraints on the evolution of complex adaptations and the means for their avoidance. Pp. 231–237_in_ Nitecki, M. H., ed. Evolutionary progress. University of Chicago Press.Google Scholar