Hostname: page-component-78c5997874-s2hrs Total loading time: 0 Render date: 2024-11-19T11:54:46.627Z Has data issue: false hasContentIssue false
  • English
  • Français

Size-related evolutionary patterns among species and subgenera in the Strombina group (Gastropoda: Columbellidae)

Published online by Cambridge University Press:  20 May 2016

Ann F. Budd  and
Kenneth G. Johnson
Ann F. Budd
Affiliation:
Department of Geology, The University of Iowa, Iowa City 52242
Kenneth G. Johnson
Affiliation:
Department of Geology, The University of Iowa, Iowa City 52242
Get access Rights & Permissions [Opens in a new window]

Abstract

This study represents a preliminary analysis of variation in size and shape in a large and diverse molluscan clade, the Strombina group, over the past 20 million years. Restored height and width were measured on 5,099 individuals of 72 species and 5 genera. Size was estimated by adding height and width, and shape was estimated by dividing height by width. Patterns of variation were analyzed quantitatively among species, subgenera, and genera using univariate statistical tests comparing means and variances and linear regression.

Results of univariate tests show that both shape and size vary among species within subgenera (the specific level) and among genera (the generic level). However, only shape varies among subgenera within genera (the subgeneric level). Regression analyses for each species show that the relationship between height and width is linear, indicating that growth is never allometric with respect to these characters. Because of this nonallometric growth, rates of shape relative to size change can never vary, imposing a severe constraint on shape change and, in turn, shape evolution. Regression models for species within subgenera have equal slopes but differ slightly in intercept. Subgeneric models differ more in intercept. Generic level models differ in slope. These results suggest that formation of species within subgenera primarily involves extension or contraction of trajectories between height and width within species (=static vectors), resulting in size change without shape change. Shape change is more important in the evolution of higher categories.

To examine overall morphologic change in the clade through time, mean sizes and shapes of species were analyzed using nonparametric statistics. Only a slight tendency exists within the clade for increase in species size, and this tendency is best expressed within two species-rich subgenera having long stratigraphic ranges. No directional trends exist for change in species shape. No relationship is found between species size and probability of speciation or extinction, or between species size and species duration, thus negating the role of species selection. Nevertheless, species are smaller in size in the northern Caribbean, a region characterized by extreme fluctuations in temperature. Larger species occurred only after a taxonomic radiation in the eastern Pacific, a more restricted region possibly characterized by reduced environmental disturbance. During this radiation, normal patterns of morphologic change associated with speciation appear to have been disrupted.

Type
Research Article
Information
Journal of Paleontology , Volume 65 , Issue 3 , May 1991 , pp. 417 - 434
Copyright
Copyright © The Paleontological Society 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Alberch, P., Gould, S. J., Oster, G. F., and Wake, D. B. 1979. Size and shape in ontogeny and phylogeny. Paleobiology, 5:296–317.Google Scholar
Alexander, R. M. 1971. Size and Shape. Edward Arnold (Publishers) Ltd., Studies in Biology no. 29, London, 59 p.Google Scholar
Boucot, A. J. 1976. Rates of size increase and of phyletic evolution. Nature, 261:694–696.Google Scholar
Brandon, R. 1982. The levels of selection, p. 315–324. In Asquith, P. and Nickles, T. (eds.), PSA, 1982, Vol. 1. The Philosophy of Science Association, East Lansing, Michigan.Google Scholar
Cheverud, J. M. 1982. Relationships among ontogenetic, static, and evolutionary allometry. American Journal of Physical Anthropology, 59:139–149.Google Scholar
Gould, S. J. 1966. Allometry and size in ontogeny and phylogeny. Biological Review, 41:587–640.CrossRefGoogle ScholarPubMed
Gould, S. J. 1966. Allometry and size in ontogeny and phylogeny. Biological Review, 41:587–640. 1984. Morphological channeling by structural constraint: convergence in styles of dwarfing and gigantism in Cerion, with a description of two new fossil species and a report on the discovery of the largest Cerion. Paleobiology, 10:172–194.Google Scholar
Hallam, A. 1975. Evolutionary size increase and longevity in Jurassic bivalves and ammonites. Nature, 258:493–496.Google Scholar
Jablonski, D. 1986. Evolutionary consequences of mass extinctions, p. 313–329. In Raup, D. M. and Jablonski, D. (eds.), Patterns and Processes in the History of Life. Springer-Verlag, Berlin.Google Scholar
Jablonski, D. 1987. How pervasive is Cope's Rule? A test using late Cretaceous mollusks. Geological Society of America, Abstracts with Programs, 19:713–714.Google Scholar
Jung, P. 1989. Revision of the Strombina-Group (Gastropoda: Columbellidae), Fossil and Living. Distribution, Biostratigraphy, and Systematics. Schweizerische Paläontologische Abhandlungen, 111, 298 p.Google Scholar
Kluge, A. G., and Strauss, R. E. 1985. Ontogeny and systematics. Annual Review of Ecology and Systematics, 16:247–268.Google Scholar
LaBarbera, M. 1986. The evolution and ecology of body size, p. 69–98. In Raup, D. M. and Jablonski, D. (eds.), Patterns and Processes in the History of Life. Springer-Verlag, Berlin.Google Scholar
Lemen, C. A., and Freeman, P. W. 1984. The genus: a macroevolutionary problem. Evolution, 38:1219–1237.Google Scholar
Lessa, E. P., and Patton, J. L. 1989. Structural constraints, recurrent shapes, and allometry in pocket gophers (genus Thomomys). Biological Journal of the Linnean Society, 36:349–363.Google Scholar
McKinney, M. L. 1986. Ecological causation of heterochrony: a test and implications for evolution theory. Paleobiology, 12:282–289.Google Scholar
Miller, R. G. Jr. 1981. Simultaneous Statistical Inference, 2nd edition. Springer Series in Statistics, Springer-Verlag, New York, 299 p.Google Scholar
Peters, R. H. 1983. The Ecological Implications of Body Size. Cambridge University Press, Cambridge, U.K., 329 p.Google Scholar
Petuch, E. J. 1982. Geographical heterochrony: contemporaneous coexistence of Neogene and Recent molluscan faunas in the Americas. Palaeogeography, Palaeoclimatology, Palaeoecology, 37:277–312.Google Scholar
Raup, D. M. 1966. Geometric analyses of shell coiling: general problems. Journal of Paleontology, 40:1178–1190.Google Scholar
SAS Institute, Inc. 1985. SAS User's Guide: Statistics, Version 5 Edition. SAS Institute, Inc., Cary, North Carolina, 956 p.Google Scholar
Schmidt-Nielsen, K. 1984. Scaling: Why is Animal Size so Important? Cambridge University Press, Cambridge, U.K., 241 p.Google Scholar
Sokal, R. R., and Rohlf, F. J. 1981. Biometry, 2nd edition. W. H. Freeman and Company, San Francisco, 859 p.Google Scholar
Stanley, S. M. 1973. An explanation for Cope's Rule. Evolution, 27:1–26.Google Scholar
Stanley, S. M. 1975. A theory of evolution above the species level. Proceedings of the National Academy of Sciences U.S.A., 72:646–650.Google Scholar
Stanley, S. M. 1986. Anatomy of a regional mass extinction: Plio-Pleistocene decimation of the Western Atlantic bivalve fauna. Palaios, 1:17–36.Google Scholar
Van Valen, L. 1973. Body size and numbers of plants and animals. Evolution, 27:27–35.Google Scholar
Van Valen, L. 1975. Group selection, sex, and fossils. Evolution, 29:87–94.Google Scholar
Vermeij, G. J. 1978. Biogeography and Adaptation: Patterns of Marine Life. Harvard University Press, Cambridge, Massachusetts, 332 p.Google Scholar
Vermeij, G. J. 1986. Survival during biotic crises: the properties and evolutionary significance of refuges, p. 231–246. In Elliott, D. K. (ed.), Dynamics of Extinction. John Wiley & Sons, New York.Google Scholar
Vrba, E. S. 1983. Macroevolutionary trends: new perspectives on the roles of adaptation and incidental effect. Science, 221:387–389.Google Scholar