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The paradox of gradualism: phyletic evolution in two lineages of lymnocardiid bivalves (Lake Pannon, central Europe)

Published online by Cambridge University Press:  08 April 2016

Dana H. Geary
Affiliation:
Department of Geoscience, University of Wisconsin, Madison, Wisconsin 53706. E-mail: [email protected]
Gene Hunt
Affiliation:
Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, NHB MRC 121, Post Office Box 37012, Washington D.C. 20013-7012
Imre Magyar
Affiliation:
Department of Geoscience, University of Wisconsin, Madison, Wisconsin 53706. E-mail: [email protected]
Holly Schreiber
Affiliation:
Department of Geoscience, University of Wisconsin, Madison, Wisconsin 53706. E-mail: [email protected]

Abstract

Patterns preserved in the fossil record are of the highest importance in addressing questions about long-term evolutionary processes, yet both the description of pattern and its translation into process can be difficult. With respect to gradual phyletic change, we know that randomly generated sequences may exhibit characteristics of a “trend” apparent patterns, therefore, must be interpreted with caution. Furthermore, even when the claim of a gradual trend can be statistically justified, interpretation of the underlying mechanisms may be challenging. Given that we can observe populations changing rapidly over tens or hundreds of years, it is now more difficult to explain instances of geologically gradual (as opposed to punctuated) change.

Here we describe morphologic change in two bivalve lineages from the late Miocene Lake Pannon. We evaluate change according to the model-based methods of Hunt. Both lineages exhibit size increases and shape changes over an interval of nearly 4 million years. Size and two shape variables in the conjungens lineage are best fit by a model of directional evolution; remaining shape variables mostly conform to unbiased random walks. Body-size evolution in the diprosopum lineage is also significantly directional but all shape variables are best fit by the unbiased random walk model; the small number of sampling intervals available for this lineage (n = 6) makes determination of the actual pattern more difficult. Model-fitting results indicate that the parallel trajectories of increasing log shell height over time in the two lineages can be accounted for by an underlying trend shared by both lineages, suggesting that the size increases may be a shared response to the same cause. The pace of phenotypic change, measured as Lynch's Δ, is slower than the neutral expectation for all size and shape traits.

Our examples illustrate well the paradox of gradualism; the sequences exhibit significant directional morphological evolution, but rates of change as measured over the long-term are apparently too slow for directional selection or even drift to be the cause. Viewing long-term phenotypic evolution in terms of populations tracking peaks on adaptive landscapes is useful in this context. Such a view allows for intervals of directional selection (during times of peak movement–resulting in the overall trends we can detect) interspersed with intervals of stasis (during times of peak stability–resulting in overall changes that appear to proceed more slowly than the neutral expectation). The paradox of gradualism thus reduces to (1) peak movements and their drivers, which are not restricted in rate as are population-genetic drivers, and (2) the maintenance of stasis, on which no consensus exists.

We can identify no environmental parameter in the central European Neogene that exhibits consistent change across the interval of gradual morphologic change. It may be that in Lake Pannon the long-term persistence of generally ameliorating conditions (plentiful resources and habitat space, few predators or competitors) resulted in geologically slow but consistent peak shifts, which in turn facilitated size increase and shape change in these lineages.

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Articles
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Copyright © The Paleontological Society 

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References

Literature Cited

Agustí, J., Cabrera, L., Garcés, M., Krijgsman, W., Oms, O., and Pares, J. M. 2001. A calibrated mammal scale for the Neogene of western Europe: state of the art. Earth-Science Reviews 52:247260.Google Scholar
Akaike, H. 1974. A new look at the statistical model identification. IEEE Transactions on Automatic Control 19:716723.Google Scholar
Anderson, D. R., Burnham, K. P., and Thompson, W. L. 2000. Null hypothesis testing: problems, prevalence, and an alternative. Journal of Wildlife Management 64:912923.CrossRefGoogle Scholar
Angilletta, M. J., Steury, T. D., and Sears, M. W. 2004. Temperature, growth rate, and body size in ectotherms: fitting pieces of a life-history puzzle. Integrative and Comparative Biology 44:498509.CrossRefGoogle Scholar
Arnold, S. J., Pfrender, M. E., and Jones, A. G. 2001. The adaptive landscape as a conceptual bridge between micro- and macroevolution. Genetica 112–113:932.Google Scholar
Basch, O. 1990. Cardiidae (Mollusca, Lamellibranchiata) pontskog kata u Hrvatskoj (Cardiidae (Mollusca, Lamellibranchiata) der pontischen Stufe in Kroatien). Palaeontologia Jugoslavia 39:1158.Google Scholar
Bell, M. A., Travis, M. P., and Blow, D. M. 2006. Inferring natural selection in a fossil threespine stickleback. Paleobiology 32:562577.Google Scholar
Benkman, C. W. 2003. Divergent selection drives the adaptive radiation of crossbills. Evolution 57:11761181.Google Scholar
Bookstein, F. L. 1987. Random walk and the existence of evolutionary rates. Paleobiology 13:446464.Google Scholar
Bookstein, F. L. 1988. Random-walk and the biometrics of morphological characters. Evolutionary Biology 23:369398.CrossRefGoogle Scholar
Brooks, R., Hunt, J., Blows, M. W., Smith, M. J., Bussiere, L. F., and Jennions, M. D. 2005. Experimental evidence for multivariate stabilizing sexual selection. Evolution 59:871880.Google Scholar
Carroll, S. P., Hendry, A. P., Reznick, D. N., and Fox, C. W. 2007. Evolution on ecological time-scales. Functional Ecology 21:387393.CrossRefGoogle Scholar
Cheetham, A. H., and Jackson, J. B. C. 1995. Process from pattern: tests for selection versus random change in punctuated bryozoan speciation. Pp. 184207 in Erwin, D. H. and Anstey, R. L., eds. New approaches to speciation in the fossil record. Columbia University Press, New York.Google Scholar
Clegg, S. M., Degnan, S. M., Mortiz, C., Estoup, A., Kikkawa, J., and Owens, I. P. F. 2002. Microevolution in island forms: the roles of drift and directional selection in morphological divergence of a passerine bird. Evolution 56:20902099.Google Scholar
Cloetingh, S. A. P. L., Horváth, F., Bada, G., and Lankreijer, A. C., eds. 2002. Neotectonics and surface processes: the Pannonian Basin and Alpine/Carpathian System. European Geosciences Union, Stephan Mueller Special Publication Series 3. Copernicus, Göttingen.Google Scholar
Eldredge, N. 2003. The sloshing bucket: how the physical realm controls evolution. Pp. 332 in Crutchfield, J. P. and Schuster, P., eds. Evolutionary dynamics. Oxford University Press, Oxford.Google Scholar
Eldredge, N., and Gould, S. J. 1972. Punctuated equilibria: an alternative to phyletic gradualism. Pp. 82115 in Schopf, T. J. M., ed. Models in paleobiology. Freeman Cooper, San Francisco.Google Scholar
Eldredge, N., Thompson, J. N., Brakefield, P. M., Gavrilets, S., Jablonski, D., Jackson, J. B. C., Lenski, R. E., Lieberman, B. S., McPeek, M. A., and Miller, W. III. 2005. The dynamics of evolutionary stasis. Paleobiology 31:133–45.Google Scholar
Elston, D. P., Lantos, M., and Hamor, T. 1994. High resolution polarity records and the stratigraphic and magnetostratigraphic correlation of late Miocene and Pliocene (Pannonian s.l.) deposits of Hungary. Pp. 111142 in Teleki, P. G., Mattick, R. E., and Kokai, J., eds. Basin analysis in petroleum exploration: a case study from the Bekes basin, Hungary. Kluwer Academic, Dordrecht.Google Scholar
Estes, S., and Arnold, S. J. 2007. Resolving the paradox of stasis: models with stabilizing selection explain evolutionary divergence on all timescales. American Naturalist 169:227244.Google Scholar
Fortelius, M., Eronen, J., Liu, L., Pushkina, D., Tesakov, A., Vislobokova, I., and Zhang, Z. 2006. Late Miocene and Pliocene large land mammals and climatic changes in Eurasia. Palaeogeography, Palaeoecology, Palaeoclimatology 238:219227.Google Scholar
Fortey, R. A. 1985. Gradualism and punctuated equilibria as competing and complementary theories. Special Papers in Palaeontology 33:1728.Google Scholar
Geary, D. H. 1990. Patterns of evolutionary tempo and mode in the radiation of melanopsid gastropods. Paleobiology 16:492511.Google Scholar
Geary, D. H. 1992. An unusual pattern of divergence between fossil melanopsid gastropods: hybridization, dimorphism, or ecophenotypy? Paleobiology 18:97113.Google Scholar
Geary, D. H. 1995. Investigating species-level transitions in the fossil record: the importance of geologically gradual change. Pp. 6786 in Erwin, D. H. and Anstey, R. A., eds. New approaches to speciation in the fossil record. Columbia University Press.Google Scholar
Geary, D. H., Rich, J. A., Valley, J. W., and Baker, K. 1989. Stable isotopic evidence of salinity change: influence on the evolution of melanopsid gastropods in the Late Miocene Pannonian basin. Geology 17:981985.Google Scholar
Geary, D. H., Magyar, I., and Müller, P. 2000. Ancient Lake Pannon and its endemic molluscan Fauna (Central Europe; Mio-Pliocene). In Rossiter, A. and Kawanabe, H., eds. Biology of ancient lakes. Advances in Ecological Research 31:463482.CrossRefGoogle Scholar
Geary, D. H., Staley, A. W., Müller, P., and Magyar, I. 2002. Iterative changes in Lake Pannon Melanopsis reflect a recurrent theme in gastropod morphological evolution. Paleobiology 28:208221.Google Scholar
Gingerich, P. D. 1993. Quantification and comparison of evolutionary rates. American Journal of Science 295-A:453478.Google Scholar
Gingerich, P. D. 2001. Rates of evolution on the time scale of the evolutionary process. Genetica 112-113:127144.Google Scholar
Gould, S. J. 1977. Ontogeny and phylogeny. Harvard University Press, Cambridge.Google Scholar
Gould, S. J. 2002. The Structure of evolutionary theory. Belknap Press of Harvard University Press, Cambridge.Google Scholar
Gould, S. J., and Eldredge, N. 1986. Punctuated equilibrium at the third stage. Systematic Zoology 35:143148.Google Scholar
Hannisdal, B. 2006. Phenotypic evolution in the fossil record: numerical experiments. Journal of Geology 114:133153.CrossRefGoogle Scholar
Hannisdal, B. 2007. Inferring phenotypic evolution in the fossil record by Bayesian inversion. Paleobiology 33:98115.Google Scholar
Hansen, T. F., and Houle, D. 2004. Evolvability, stabilizing selection, and the problem of stasis. Pp. 130150 in Pigliucci, M. and Preston, K., eds. Phenotypic integration. Oxford University Press, Oxford.CrossRefGoogle Scholar
Harzhauser, M., and Piller, W. E. 2007. Benchmark data of a changing sea: palaeogeography, palaeobiogeography and events in the Central Paratethys during the Miocene. Palaeogeography, Palaeoclimatology, Palaeoecology 253:831.Google Scholar
Harzhauser, M., Daxner-Höck, G., and Piller, W. E. 2004. An integrated stratigraphy of the Pannonian (Late Miocene) in the Vienna Basin. Austrian Journal of Earth Sciences 95-96:619.Google Scholar
Harzhauser, M., Latal, C., and Piller, W. E. 2007. The stable isotope archive of Lake Pannon as a mirror of Late Miocene climate change. Palaeogeography, Palaeoclimatology, Palaeoecology 249:335350.CrossRefGoogle Scholar
Hendry, A. P., and Kinnison, M.T. 1999. The pace of modern life: measuring rates of contemporary microevolution. Evolution 53:16371653.Google Scholar
Horváth, F., Bada, G., Szafián, P., Tari, G., Ádám, A., and Cloetingh, S. 2006. Formation and deformation of the Pannonian Basin: constraints from observational data. In Gee, D. G. and Stephenson, R. A., eds. European lithosphere dynamics. Geological Society of London Memoir 32:191206.Google Scholar
Huey, R. B., Gilchrist, G. W., Carlson, M. L., Berrigan, D., and Serra, L. 2000. Rapid evolution of a geographic cline in size in an introduced fly. Science 287:308309.Google Scholar
Hunt, G. 2006. Fitting and comparing models of phyletic evolution: random walks and beyond. Paleobiology 32:578601.Google Scholar
Hunt, G. 2007. The relative importance of directional change, random walks, and stasis in the evolution of fossil lineages. Proceedings of the National Academy of Sciences USA 104:1840418408.CrossRefGoogle Scholar
Hunt, G. 2008a. Evolutionary patterns within fossil lineages: model-based assessment of modes, rates, punctuations and process. In Bambach, R. K., and Kelley, P. H., eds. From evolution to geobiology: research questions driving paleontology at the start of a new century. Paleontological Society Papers 14:117131.Google Scholar
Hunt, G. 2008b. Gradual or pulsed evolution: when should punctuational explanations be preferred? Paleobiology 34:360377.CrossRefGoogle Scholar
Hunt, G., Bell, M. A., and Travis, M. P. 2008. Evolution toward a new adaptive optimum: phenotypic evolution in a fossil stickleback lineage. Evolution 62:700710.CrossRefGoogle Scholar
Ivanov, D., Ashraf, A. R., Mosbrugger, V., and Palamarev, E. 2006. Palynological evidence for Miocene climate change in the Forecarpathian Basin (Central Paratethys, NW Bulgaria). Palaeogeography, Palaeoecology, Palaeoclimatology 178:1937.CrossRefGoogle Scholar
Jablonski, D. 1996. Body size and macroevolution. Pp. 256289 in Jablonski, D., Erwin, D. H., and Lipps, J. H., eds. Evolutionary paleobiology. University of Chicago Press, Chicago.Google Scholar
Jiricek, R. 1990. Pontien in der Tschechoslowakei. Pp. 276284 in Stevanovic, P. M., Nevesskaya, L. A., Marinescu, F., Sokac, A., and Jámbor, Á., eds. Chronostratigraphie und Neostratotypen, Neogen der Westlichen (“Zentrale”) Paratethys 8, Pontien. Jazu and Sanu, Zagreb-Belgrade.Google Scholar
Juhasz, Gy 1992. Lithostratigrapical and sedimentological framework of the Pannonian (s.l.) sedimentary sequence in the Hungarian Plain (Alfold), Eastern Hungary. Acta Geologica Hungarica 34:5372.Google Scholar
Kazmer, M. 1990. Birth, life, and death of the Pannonian Lake. Palaeogeography, Palaeoclimatology, Palaeoecology 79:171188.Google Scholar
Kingsolver, J. G., Hoekstra, H. E., Hoekstra, J. M., Berrigan, D., Vignieri, S. N., Hill, C. E., Hoang, A., Gilbert, P., and Beerli, P. 2001. The strength of phenotypic selection in natural populations. American Naturalist 157:245261.CrossRefGoogle Scholar
Kinnison, M. T., and Hendry, A. P. 2001. The pace of modern life. II. From rates of contemporary microevolution to pattern and process. Genetica 112-113:145164.Google Scholar
Kovac, M., Baráth, I., Fordinál, K., Grigoriovich, A.S., Halásová, E., Hudácková, N., Joniak, P., Sabol, M., Slamková, M., Sliva, L., and Vojtko, R. 2006. Late Miocene to Early Pliocene sedimentary environments and climatic changes in the Alpine-Carpathian-Pannonian junction area: a case study from the Danube Basin northern margin (Slovakia). Palaeogeography, Palaeoecology, Palaeoclimatology 238:3252.Google Scholar
Kovacic, M., and Grizelj, A. 2006. Provenance of the Upper Miocene clastic material in the southwestern part of the Pannonian Basin. Geologica Carpathica 57:495510.Google Scholar
Kozłowski, J., and Teriokhin, A. T. 1999. Allocation of energy between growth and reproduction: the Pontryagin Maximum Principle solution for the case of age- and season-dependent mortality. Evolutionary Ecology Research 1:423441.Google Scholar
Krézsek, C., and Filipescu, S. 2005. Middle to late Miocene sequence stratigraphy of the Transylvanian Basin (Romania). Tectonophysics 410:437463.Google Scholar
Lande, R. 1980. Genetic variation and phenotypic evolution during allopatric speciation. American Naturalist 116:463479.Google Scholar
Lennert, J., Szónoky, M., Geary, D. H., and Magyar, I. 1999. The Lake Pannon fossils of the Bátaszék brickyard. Acta Geologica Hungarica 42:6788.Google Scholar
Lieberman, B. S., and Dudgeon, S. 1996. An evaluation of stabilizing selection as a mechanism for stasis. Palaeogeography, Palaeoclimatology, Palaeoecology 127:229238.Google Scholar
Lieberman, B. S., Brett, C. E., and Eldredge, N. 1994. Patterns and processes of stasis in two species lineages of brachiopods from the Middle Devonian of New York State. American Museum Novitates 3114:123.Google Scholar
Lieberman, B. S. 1995. A study of stasis and change in two species lineages from the Middle Devonian of New York state. Paleobiology 21:1527.Google Scholar
Lörenthey, E. 1894. Die oberen pontischen Sedimente und deren Fauna bei Szegárd, Nagy-Mányok und Árpád. Mitteilungen aus dem Jahrbuche der Kön. Ungarischen Geologischen Anstalt 10:73160.Google Scholar
Lourens, L. J., Hilgen, F. J., Shackleton, N. J., Laskar, J., and Wilson, D. 2004. The Neogene Period. Pp. 469471 in Gradstein, F., Ogg, J., and Smith, A. G., eds. A geologic time scale 2004. Cambridge University Press, Cambridge.Google Scholar
Lueger, J. P. 1978. Klimaentwicklung im Pannon und Pont des Wiener Beckens aufgrund von Landschneckenfaunen. Anzeiger der math.-naturw. Klasse der Osterreichischen Akademie der Wissenschaften 1978/6:137149.Google Scholar
Lynch, M. 1988. The rate of polygenic mutation. Genetical Research 51:137148.Google Scholar
Lynch, M. 1990. The rate of morphological evolution in mammals from the standpoint of the neutral expectation. American Naturalist 136:727741.CrossRefGoogle Scholar
Lynch, M., and Hill, W. G. 1986. Phenotypic evolution by neutral mutation. Evolution 40:915935.Google Scholar
MacLeod, N. 1999. Generalizing and extending the eigenshape method of shape space visualization and analysis. Paleobiology 25:107138.Google Scholar
Magyar, I., and Sztanó, O. 2008. Is there a Messinian unconformity in the Central Paratethys? Stratigraphy 5:247257.CrossRefGoogle Scholar
Magyar, I., Geary, D. H., and Müller, P. 1999a. Paleogeographic evolution of the Late Miocene Lake Pannon in the Carpathian basin. Palaeogeography, Palaeoecology, Palaeoclimatology 147:151167.Google Scholar
Magyar, I., Geary, D., Sütõ-Szentai, M., Lantos, M., and Müller, P. 1999b. Integrated bio-, magneto- and chronostratigraphie correlations of the Late Miocene Lake Pannon deposits. Acta Geologica Hungarica 42:532.Google Scholar
Magyar, I., Müller, P., Geary, D. H., Sanders, H. C., and Tari, G. C. 2000. Diachronous deposits of Lake Pannon in the Kisalföld basin reflect basin and mollusc evolution. Abhandlungen der Geologischen Bundesanstalt Band 56-2:669678.Google Scholar
Magyar, I., Lantos, M., Ujszászi, K., and Kordos, L. 2007. Magnetostratigraphic, seismic and biostratigraphic correlations of the Upper Miocene sediments in the northwestern Pannonian Basin System. Geologica Carpathica 58:277290.Google Scholar
Mátyás, J., Burns, S. J., Müller, P., and Magyar, I. 1996. What can stable isotopes say about salinity? An example from the Late Miocene Pannonian Lake. Palaios 11:3139.Google Scholar
Müller, P., and Magyar, I. 1992. Continuous record of the evolution of lacustrine cardiid bivalves in the Late Miocene Pannonian Lake. Acta Palaeontologica Polonica 36:353372.Google Scholar
Müller, P., Geary, D. H., and Magyar, I. 1999. The endemic molluscs of the Late Miocene Lake Pannon: their origin, evolution, and family-level taxonomic review. Lethaia 32:4760.Google Scholar
Nargolwalla, M. C., Hutchison, M. P., and Begun, D. R. 2006. Middle and Late Miocene terrestrial vertebrate localities and paleoenvironments in the Pannonian Basin. Beitrage Paläontologisches 30:347360.Google Scholar
Nagymarosy, A., and Müller, P. 1988. Some aspects of Neogene biostratigraphy in the Pannonian basin. In Royden, L. and Horváth, F., eds. The Pannonian Basin: a study in basin evolution. AAPG Memoir 45:6977. American Association of Petroleum Geologists, Tulsa, Okla.Google Scholar
Papp, A., Marinescu, F., and Senes, J. 1974. Chronostratigraphie und Neostratotypen. Miozan der Zentralen Paratethys 4, Sarmatien. VEDA, Bratislava.Google Scholar
Papp, A., Jámbor, Á. and Steininger, F. F., eds. 1985. Chronostratigraphie und Neostratotypen. Miozan der Zentralen Paratethys 7, Pannonien. Akadémiai Kiadõ, Budapest.Google Scholar
Partridge, L., and Coyne, J. A. 1997. Bergmann's Rule in ectotherms: is it adaptive? Evolution 51:632635.Google Scholar
Pfennig, D. W., Rice, A. M., and Martin, R. A. 2007. Field and experimental evidence for competition's role in phenotypic divergence. Evolution 61:257271.Google Scholar
Pogacsas, Gy., Lakatos, L., Ujszaszi, K., Vakarcs, G., Varkonyi, L., Varnai, P., and Revesz, I. 1988. Seismic facies, electro facies and Neogene sequence chronology of the Pannonian Basin. Acta Geologica Hungarica 31:175207.Google Scholar
Popov, S. V., Rögl, R., Rozanov, A. Y., Steininger, F. F., Shcherba, I. G., and Kovac, M., eds. 2004. Lithological-paleogeographic maps of Paratethys: 10 maps Late Eocene to Pliocene. Courier Forschungsinstitut Senckenberg 250:14:6.Google Scholar
Popov, S. V., Shcherba, I. G., Ilyina, L. B., Nevesskaya, L. A., Paramonova, N. P., Khondkarian, S. O., and Magyar, I. 2006. Late Miocene to Pliocene palaeogeography of the Paratethys and its relation to the Mediterranean. Palaeogeography, Palaeoclimatology, Palaeoecology 238:91106.Google Scholar
Raup, D. M. 1977. Stochastic models in evolutionary paleobiology. Pp. 5978 in Hallam, A., ed. Patterns of evolution as illustrated by the fossil record. Elsevier, Amsterdam.CrossRefGoogle Scholar
Raup, D. M., and Crick, R. E. 1981. Evolution of single characters in the Jurassic ammonite Kosmoceras . Paleobiology 7:200215.Google Scholar
Reznick, D. N., Shaw, F. H., Rodd, F. H., and Shaw, R. G. 1997. Evaluation of the rate of evolution in natural populations of guppies (Poecilia reticulata). Science 275:19341936.Google Scholar
Rögl, F. 1998. Paleogeographic considerations for Mediterranean and Paratethys seaways (Oligocene to Miocene). Annals Naturhistorische Museum Wien 85A:135163.Google Scholar
Rögl, F., and Daxner-Höck, G. 1996. Late Miocene Paratethys correlations. Pp. 4755 in Bernor, R. L., Fahlbusch, V., and Mittmann, H.-W., eds. The evolution of western Eurasian Neogene mammal faunas. Columbia University Press, New York.Google Scholar
Roopnarine, P. D. 2001. The description and classification of evolutionary mode: a computational approach. Paleobiology 27:446465.Google Scholar
Roopnarine, P. D., Byars, G., and Fitzgerald, P. 1999. Anagenetic evolution, stratophenetic patterns, and random walk models. Paleobiology 25:4157.Google Scholar
Schluter, D. 2000. The ecology of adaptive radiation. Oxford University Press, Oxford.Google Scholar
Schneider, J. A., and Magyar, I. 1999. Evolution of brackish- and freshwater cockles (Bivalvia: Cardiidae) in the central and eastern Paratethys. Geological Society of America Annual Meeting Abstracts with Programs 31(7):399.Google Scholar
Seed, R., and Brown, R. A. 1977. A comparison of the reproductive cycles of Modiolus modiolus (L.), Cerastoderma (= Cardium) edule (L.), and Mytilus edulis (L.) in Strangford Lough, Northern Ireland. Oecologia 30:173188.Google Scholar
Sheets, H. D., and Mitchell, C. E. 2001a. Uncorrelated change produces the apparent dependence of evolutionary rate on interval. Paleobiology 27:429445.Google Scholar
Sheets, H. D., and Mitchell, C. E. 2001b. Why the null matters: statistical tests, random walks and evolution. Genetica 112-113:105125.Google Scholar
Simpson, G. G. 1944. Tempo and mode in evolution. Columbia University Press, New York.Google Scholar
Stevanovic, P. M., Nevesskaya, L. A., Marinescu, F., Sokac, A., and Jámbor, Á., eds. 1990. Chronostratigraphie und Neostratotypen, Neogen der Westlichen (Zentrale) Paratethys 8, Pontien. Jazu and Sanu, Zagreb-Belgrade.Google Scholar
Strauch, F. 1968. Determination of Cenozoic sea-temperatures using Hiatella arctica (Linné). Palaeogeography, Palaeoclimatology, Palaeoecology 5:213233.Google Scholar
Szonoky, M., Dobos-Hortobagyi, E., Gulyás, S., Müller, P., Szuromi-Korecz, A., Geary, D. H., and Magyar, I. 1999. Arpad, a classic locality of Lake Pannon bivalves. Acta Geologica Hungarica 42:89108.Google Scholar
Thamó-Bozsó, E., Juhász, Gy., and Kovács, L. Ó. 2006. The mineral composition of the Pannonian s.l. formations in the Hungarian Plain. I. The characteristics and origins of the Pannonian s.l. sands and sandstones. Földtani Közlöny 136:407430.Google Scholar
Thomas, C. D., Bodsworth, E. J., Wilson, R. J., Simmons, A. D., Davies, Z. G., Musche, M., and Conradt, L. 2001. Ecological and evolutionary processes at expanding range margins. Nature 411:577581.Google Scholar
Thompson, J. N. 1998. Rapid evolution as an ecological process. Trends in Ecology and Evolution 13:329332.Google Scholar
Travis, J. 1989. The role of optimizing selection in natural populations. Annual Review of Ecology and Systematics 20:279296.Google Scholar
Tyler-Walters, H. 2007. Cerastoderma edule. Common cockle. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [online]. Marine Biological Association of the United Kingdom, Plymouth. http://www.marlin.ac.uk/species/Cerastodermaedule.htm Google Scholar
Vakarcs, G., Vail, P. R., Tari, G., Pogácsás, G., Mattick, R. E., and Szabó, A. 1994. Third-order Middle Miocene-Early Pliocene depositional sequences in the prograding delta complex of the Pannonian basin. Tectonophysics 240:81106.Google Scholar
van Dam, J. A. 2006. Geographic and temporal patterns in the late Neogene (12–3 Ma) aridification of Europe: the use of small mammals as paleoprecipitation proxies. Palaeogeography, Palaeoecology, Palaeoclimatology 238:190218.Google Scholar
Van Voorhies, W. A. 1996. Bergmann size clines: a simple explanation for their occurrence in ectotherms. Evolution 50:12591264.Google Scholar
Walker, J. A. 1998. QuicKurve. http://www.usm.maine.edu/∼walker/software.html Google Scholar
Wilk, J., and Bieler, R. 2009. Ecophenotypic variation in the Flat Tree Oyster, Isognomon alatus (Bivalvia: Isognomonidae), across a tidal microhabitat gradient. Marine Biology Research, doi:10.1080/17451000802279644.Google Scholar