Hostname: page-component-76d6cb85b7-8p85h Total loading time: 0 Render date: 2026-07-20T04:02:35.139Z Has data issue: false hasContentIssue false
  • English
  • Français

Time-averaging, evolution, and morphologic variation

Published online by Cambridge University Press:  08 February 2016

Andrew M. Bush ,
Matthew G. Powell ,
William S. Arnold ,
Theresa M. Bert  and
Gwen M. Daley
Andrew M. Bush
Affiliation:
Department of Geological Sciences, Virginia Tech, 4044 Derring Hall, Blacksburg, Virginia 24061-0420
Matthew G. Powell
Affiliation:
Department of Geological Sciences, Virginia Tech, 4044 Derring Hall, Blacksburg, Virginia 24061-0420
William S. Arnold
Affiliation:
Florida Marine Research Institute, 100 Eighth Avenue Southeast, St. Petersburg, Florida 33701-5095. E-mail: Bill.Arnold@fwc.state.fl.us, E-mail: theresa.bert@fwc.state.fl.us
Theresa M. Bert
Affiliation:
Florida Marine Research Institute, 100 Eighth Avenue Southeast, St. Petersburg, Florida 33701-5095. E-mail: Bill.Arnold@fwc.state.fl.us, E-mail: theresa.bert@fwc.state.fl.us
Gwen M. Daley
Affiliation:
Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 53706. E-mail: gdaley@geology.wisc.edu
Get access Rights & Permissions [Opens in a new window]

Abstract

Many fossil assemblages are time-averaged, with multiple generations of organisms mixed into a single stratigraphic horizon. A time-averaged sample of a taxon should be more variable than a single-generation sample if enough morphologic change occurred during the interval of time-averaging. Time-averaging may also alter correlations between morphologic variables and obscure allometric relationships in an evolving population. To investigate these issues, we estimated the variability of six modern, single-generation samples of the bivalve Mercenaria campechiensis using Procrustes analysis and compared them with several time-averaged Pleistocene samples of M. campechiensis and M. permagna. Both the modern and the fossil samples ranged in variability, but these ranges were virtually identical. Morphology was quite stable over the hundreds to many thousands of years that passed as the assemblages accumulated, and the variabilities of the fossil samples could be used to estimate single-generation variability. At one fossil locality, the environment and paleocommunity changed partway through the collection interval; the morphology of Mercenaria appears stable above and below the transition but changes across it. This change is similar in magnitude to the differences between geographically separated modern populations, whereas temporal variation within single environmental settings is distinctly less than geographic variation. Analytical time-averaging (the mixing of fossils from different horizons) between paleocommunities increased variability slightly (but not significantly) above that found in living populations. While its constituent populations appear stable on millennial timescales, M. campechiensis has been evolutionarily static since at least the early to middle Pleistocene.

Information

Type
Articles
Information
Paleobiology , Volume 28 , Issue 1 , Winter 2002 , pp. 9 - 25
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.)

Article purchase

Temporarily unavailable

References

Literature Cited

Arnold, W. S., Bert, T. M., Marelli, D. C., Cruz-Lopez, H., and Gill, P. A. 1996. Genotype-specific growth of hard clams (genus Mercenaria) in a hybrid zone: variation among habitats. Marine Biology 125:129–139.CrossRefGoogle Scholar
Bader, R. S. 1954. Variability and evolutionary rate in the oreodonts. Evolution 9:119–140.CrossRefGoogle Scholar
Bambach, R. K. 1973. Tectonic deformation of composite-mold fossil Bivalvia (Mollusca). American Journal of Science 273(A):409–430.Google Scholar
Behrensmeyer, A. K., and Hook, R. W. 1992. Paleoenvironmental contexts and taphonomic modes. Pp. 15–136in Behrensmeyer, A. K., Damuth, J. D., DiMichele, W. A., Potts, R., Sues, H. D., and Wing, S. L., eds. Terrestrial ecosystems through time. University of Chicago Press, Chicago.Google Scholar
Bell, M. A., Sadagursky, M. S., Baumgartner, J. V. 1987. Utility of lacustrine deposits for the study of variation within fossil assemblages. Palaios 2:455–466.CrossRefGoogle Scholar
Bert, T. M., and Arnold, W. S. 1995. An empirical test of predictions of two competing models for the maintenance and fate of hybrid zones: both models are supported in a hard-clam hybrid zone. Evolution 49:276–289.CrossRefGoogle Scholar
Bert, T. M., Hesselman, D. M., Arnold, W. S., Moore, W. S., Cruz-Lopez, H., and Marelli, D. C. 1993. High frequency of gonadal neoplasia in a hard clam (Mercenaria spp.) hybrid zone. Marine Biology 117:97–104.CrossRefGoogle Scholar
Bookstein, F. L. 1991. Morphometric tools for landmark data: geometry and biology. Cambridge University Press, New York.Google Scholar
Bush, A. M. 2000. Evolution within demes: stasis as a hierarchical phenomenon. Geological Society of America Abstracts with Programs 32:445.Google Scholar
Chapman, R. E. 1994. Morphometric variation in fossil populations: the effect of environmental variability and taphonomic time-averaging. Geological Society of America Abstracts with Programs 26:486.Google Scholar
Charlesworth, B. 1984. Some quantitative methods for studying evolutionary patterns in single characters. Paleobiology 10:308–318.CrossRefGoogle Scholar
Cheetham, A. H. 1986. Tempo of evolution in a Neogene bryozoan: rates of morphologic change within and across species boundaries. Paleobiology 12:190–202.CrossRefGoogle Scholar
Cutler, A. H., and Flessa, K. W. 1990. Fossils out of sequence: computer simulations and strategies for dealing with stratigraphic disorder. Palaios 5:227–235.CrossRefGoogle Scholar
Daley, G. M. 1999. Environmentally controlled variation in shell size of Ambonychia Hall (Mollusca: Bivalvia) in the type Cincinnatian (Upper Ordovician). Palaios 14:520–529.CrossRefGoogle Scholar
Daley, G. M., Bush, A. M., and Geary, D. H. 2001. Using paleocommunities to frame evolutionary and paleoecological studies: an example from the Fort Thompson Formation (Pleistocene) of Florida. Geological Society of America Abstracts with Programs 33:14.Google Scholar
Dryden, I. L., and Mardia, K. V. 1998. Statistical Shape Analysis. Wiley, Chichester, England.Google Scholar
Emiliani, C. 1950. Introduction to a method for determining the physical characters of fossil environments. Journal of Paleontology 24:485–491.Google Scholar
Flessa, K. W., and Kowalewski, M. 1994. Shell survival and time-averaging in nearshore and shelf environments: estimates from the radiocarbon literature. Lethaia 27:153–165.CrossRefGoogle Scholar
Flessa, K. W., Cutler, A. H., and Meldahl, K. H. 1993. Time and taphonomy: quantitative estimates of time-averaging and stratigraphic disorder in a shallow marine habitat. Paleobiology 19:266–286.CrossRefGoogle Scholar
Fürsich, F. T. 1978. The influence of faunal condensation and mixing on the preservation of fossil benthic communities. Lethaia 11:243–250.CrossRefGoogle Scholar
Fürsich, F. T., and Aberhan, M. 1990. Significance of time-averaging for paleocommunity analysis. Lethaia 23:143–152.CrossRefGoogle Scholar
Gingerich, P. D. 1983. Rate of evolution: effects of time and temporal scaling. Science 222:159–161.CrossRefGoogle Scholar
Guthrie, R. D. 1965. Variability in characters undergoing rapid evolution, an analysis of Microtus molars. Evolution 19:214–233.CrossRefGoogle Scholar
Hulbert, R. C. Jr., and Morgan, G. S. 1989. Stratigraphy, paleoecology, and vertebrate fauna of the Leisey Shell Pit Local Fauna, early Pleistocene (Irvingtonian) of southwestern Florida. Papers in Florida Paleontology 2:1–19.Google Scholar
Hulbert, R. C. Jr., Morgan, G. S., and Webb, S. D., eds. 1995. Paleontology and geology of the Leisey Shell Pits, Early Pleistocene of Florida. Bulletin of the Florida Museum of Natural History 37.Google Scholar
Hunt, G. 2000. Time-averaging and morphometric data: do fossil samples accurately reflect population-level variability? Geological Society of America Abstracts with Programs 32:95.Google Scholar
Jones, D. S., Mueller, P. A., Acosta, T., and Shuster, R. D. 1995. Strontium isotopic stratigraphy and age estimates for the Leisey Shell Pit faunas, Hillsborough County, Florida. Bulletin of the Florida Museum of Natural History 37:93–105.Google Scholar
Kidwell, S. M. 1986. Models for fossil concentrations: paleobiologic implications. Paleobiology 12:6–24.CrossRefGoogle Scholar
Kidwell, S. M., and Aigner, T. 1985. Sedimentary dynamics of complex shell beds: implications for ecologic and evolutionary patterns. Pp. 382–395in Bayer, U. and Seilacher, A., eds. Sedimentary and evolutionary cycles. Springer; Berlin.CrossRefGoogle Scholar
Kidwell, S. M., and Bosence, D. W. J. 1991. Taphonomy and time-averaging of marine shelly faunas. Pp. 115–209in Allison, P. and Briggs, D. E. G., eds. Taphonomy: releasing the data locked in the fossil record. Plenum, New York.CrossRefGoogle Scholar
Kowalewski, M. 1996. Time-averaging, overcompleteness, and the geological record. Journal of Geology 104:317–326.CrossRefGoogle Scholar
Kowalewski, M. 1997. The reciprocal taphonomic model. Lethaia 30:86–88.CrossRefGoogle Scholar
Kowalewski, M., Goodfriend, G. A., and Flessa, K. W. 1998. High-resolution estimates of temporal mixing within shell beds: the evils and virtues of time-averaging. Paleobiology 24:287–304.Google Scholar
Lande, R. 1976. Natural selection and random genetic drift in phenotypic evolution. Evolution 30:314–334.CrossRefGoogle ScholarPubMed
Losos, J. B., Warheit, K. I., and Schoener, T. W. 1997. Adaptive differentiation following experimental island colonization in Anolis lizards. Nature 387:70–73.CrossRefGoogle Scholar
MacFadden, B. J. 1989. Dental character variation in paleopopulations and morphospecies of fossil horses and extant analogs. Pp. 128–141in Prothero, D. R. and Schoch, R. M., eds. The evolution of perissodactyls. Oxford University Press, New York.Google Scholar
Marcus, L. F., Corti, M., Loy, A., Naylor, G. J. P., and Slice, D. E., eds. 1996. Advances in morphometrics. NATO ASI Series, A 284. Plenum, New York.Google Scholar
Martin, R. E. 1999. Taphonomy: a process approach. Cambridge University Press, New York.CrossRefGoogle Scholar
Meldahl, K. H., Flessa, K. W., and Cutler, A. H. 1997. Time-averaging and postmortem skeletal survival in benthic fossil assemblages: quantitative comparisons among Holocene environments. Paleobiology 23:207–229.CrossRefGoogle Scholar
Olszewski, T. 1999. Taking advantage of time-averaging. Paleobiology 25:226–238.CrossRefGoogle Scholar
Patton, J. L., and Brylski, P. V. 1987. Pocket gophers in alfalfa fields: causes and consequences of habitat-related body size variation. American Naturalist 130:493–506.CrossRefGoogle Scholar
Portell, R. W., Schindler, K. S., and Nicol, D. 1995. Biostratigraphy and paleoecology of the Pleistocene invertebrates from the Leisey Shell Pits, Hillsborough County, Florida. Bulletin of the Florida Museum of Natural History 37:127–164.Google Scholar
Robinson, B. W., and Wilson, D. S. 1995. Experimentally induced morphological diversity in Trinidadian guppies (Poecilia reticulata). Copeia 1995:294–305.CrossRefGoogle Scholar
Rohlf, F. J., and Bookstein, F. L., eds. 1990. Proceedings of the Michigan morphometrics workshop. University of Michigan Museum of Zoology Special Publication 2.Google Scholar
Rohlf, F. J., and Marcus, L. F. 1993. A revolution in morphometries. Trends in Ecology and Evolution 8:129–132.CrossRefGoogle Scholar
Roopnarine, P. D. 2001. The description and classification of evolutionary mode: a computational approach. Paleobiology 27:446–465.2.0.CO;2>CrossRefGoogle Scholar
Sheets, H. D., and Mitchell, C. E. 2001. Uncorrelated change produces the apparent dependence of evolutionary rate on interval. Paleobiology 27:429–445.2.0.CO;2>CrossRefGoogle Scholar
Smith, L. H. 1998. Species level phenotypic variation in lower Paleozoic trilobites. Paleobiology 24:17–36.CrossRefGoogle Scholar
Stanley, S. M., and Yang, X. 1987. Approximate evolutionary stasis for bivalve morphology over millions of years: a multivariate, multilineage study. Paleobiology 13:113–139.CrossRefGoogle Scholar
Staff, G. M., and Powell, E. N. 1988. The paleoecologic significance of diversity: the effect of time averaging and differential preservation on macroinvertebrate species richness in death assemblages. Palaeogeography, Palaeoclimatology, Palaeoecology 63:73–89.CrossRefGoogle Scholar
Walker, K. R., and Bambach, R. K. 1971. The significance of fossil assemblages from fine-grained sediments: time-averaged communities. Geological Society of America Abstracts with Programs 3:783–784.Google Scholar
Wanless, H. R., Tedesco, L. P., and Tyrrell, K. M. 1988. Production of subtidal tubular and surficial tempestites by Hurricane Kate, Caicos Platform, British West Indies. Journal of Sedimentary Petrology 58:739–750.Google Scholar
Ward, L. W., and Blackwelder, B. W. 1987. Late Pliocene and early Pleistocene Mollusca from the James City and Chowan River Formation at the Lee Creek Mine. Pp. 113–283in Ray, C. E., ed. Geology and Paleontology of the Lee Creek Mine, North Carolina, II. Smithsonian Contributions to Paleobiology 61.CrossRefGoogle Scholar
Williams, H. S. 1902. Fossil faunas and their use in correlating geological formations. American Journal of Science 13:417–432.CrossRefGoogle Scholar
Williamson, P. G. 1981a. Paleontological documentation of speciation in Cenozoic molluscs from Turkana Basin. Nature 293:437–443.CrossRefGoogle Scholar
Williamson, P. G. 1981b. Morphological stasis and developmental constraint: real problems for neo-Darwinism. Nature 294:214–215.CrossRefGoogle Scholar
Williamson, P. G. 1986. Selection or constraint? A proposal on the mechanism for stasis. Pp. 129–142in Campbell, K. S., ed. Rates of evolution. Allen and Unwin, London.Google Scholar
Wilson, M. V. H. 1988. Taphonomic processes: information loss and information gain. Geosciences Canada 15:131–148.Google Scholar