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

  • Dana H. Geary (a1), Gene Hunt (a2), Imre Magyar (a1) and Holly Schreiber (a1)


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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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.
Akaike, H. 1974. A new look at the statistical model identification. IEEE Transactions on Automatic Control 19:716723.
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.
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.
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.
Basch, O. 1990. Cardiidae (Mollusca, Lamellibranchiata) pontskog kata u Hrvatskoj (Cardiidae (Mollusca, Lamellibranchiata) der pontischen Stufe in Kroatien). Palaeontologia Jugoslavia 39:1158.
Bell, M. A., Travis, M. P., and Blow, D. M. 2006. Inferring natural selection in a fossil threespine stickleback. Paleobiology 32:562577.
Benkman, C. W. 2003. Divergent selection drives the adaptive radiation of crossbills. Evolution 57:11761181.
Bookstein, F. L. 1987. Random walk and the existence of evolutionary rates. Paleobiology 13:446464.
Bookstein, F. L. 1988. Random-walk and the biometrics of morphological characters. Evolutionary Biology 23:369398.
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.
Carroll, S. P., Hendry, A. P., Reznick, D. N., and Fox, C. W. 2007. Evolution on ecological time-scales. Functional Ecology 21:387393.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Fortey, R. A. 1985. Gradualism and punctuated equilibria as competing and complementary theories. Special Papers in Palaeontology 33:1728.
Geary, D. H. 1990. Patterns of evolutionary tempo and mode in the radiation of melanopsid gastropods. Paleobiology 16:492511.
Geary, D. H. 1992. An unusual pattern of divergence between fossil melanopsid gastropods: hybridization, dimorphism, or ecophenotypy? Paleobiology 18:97113.
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.
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.
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.
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.
Gingerich, P. D. 1993. Quantification and comparison of evolutionary rates. American Journal of Science 295-A:453478.
Gingerich, P. D. 2001. Rates of evolution on the time scale of the evolutionary process. Genetica 112-113:127144.
Gould, S. J. 1977. Ontogeny and phylogeny. Harvard University Press, Cambridge.
Gould, S. J. 2002. The Structure of evolutionary theory. Belknap Press of Harvard University Press, Cambridge.
Gould, S. J., and Eldredge, N. 1986. Punctuated equilibrium at the third stage. Systematic Zoology 35:143148.
Hannisdal, B. 2006. Phenotypic evolution in the fossil record: numerical experiments. Journal of Geology 114:133153.
Hannisdal, B. 2007. Inferring phenotypic evolution in the fossil record by Bayesian inversion. Paleobiology 33:98115.
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.
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.
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.
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.
Hendry, A. P., and Kinnison, M.T. 1999. The pace of modern life: measuring rates of contemporary microevolution. Evolution 53:16371653.
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.
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.
Hunt, G. 2006. Fitting and comparing models of phyletic evolution: random walks and beyond. Paleobiology 32:578601.
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.
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.
Hunt, G. 2008b. Gradual or pulsed evolution: when should punctuational explanations be preferred? Paleobiology 34:360377.
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.
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.
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.
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.
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.
Kazmer, M. 1990. Birth, life, and death of the Pannonian Lake. Palaeogeography, Palaeoclimatology, Palaeoecology 79:171188.
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.
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.
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.
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.
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.
Krézsek, C., and Filipescu, S. 2005. Middle to late Miocene sequence stratigraphy of the Transylvanian Basin (Romania). Tectonophysics 410:437463.
Lande, R. 1980. Genetic variation and phenotypic evolution during allopatric speciation. American Naturalist 116:463479.
Lennert, J., Szónoky, M., Geary, D. H., and Magyar, I. 1999. The Lake Pannon fossils of the Bátaszék brickyard. Acta Geologica Hungarica 42:6788.
Lieberman, B. S., and Dudgeon, S. 1996. An evaluation of stabilizing selection as a mechanism for stasis. Palaeogeography, Palaeoclimatology, Palaeoecology 127:229238.
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.
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.
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.
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.
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.
Lynch, M. 1988. The rate of polygenic mutation. Genetical Research 51:137148.
Lynch, M. 1990. The rate of morphological evolution in mammals from the standpoint of the neutral expectation. American Naturalist 136:727741.
Lynch, M., and Hill, W. G. 1986. Phenotypic evolution by neutral mutation. Evolution 40:915935.
MacLeod, N. 1999. Generalizing and extending the eigenshape method of shape space visualization and analysis. Paleobiology 25:107138.
Magyar, I., and Sztanó, O. 2008. Is there a Messinian unconformity in the Central Paratethys? Stratigraphy 5:247257.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Papp, A., Marinescu, F., and Senes, J. 1974. Chronostratigraphie und Neostratotypen. Miozan der Zentralen Paratethys 4, Sarmatien. VEDA, Bratislava.
Papp, A., Jámbor, Á. and Steininger, F. F., eds. 1985. Chronostratigraphie und Neostratotypen. Miozan der Zentralen Paratethys 7, Pannonien. Akadémiai Kiadõ, Budapest.
Partridge, L., and Coyne, J. A. 1997. Bergmann's Rule in ectotherms: is it adaptive? Evolution 51:632635.
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.
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.
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.
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.
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.
Raup, D. M., and Crick, R. E. 1981. Evolution of single characters in the Jurassic ammonite Kosmoceras . Paleobiology 7:200215.
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.
Rögl, F. 1998. Paleogeographic considerations for Mediterranean and Paratethys seaways (Oligocene to Miocene). Annals Naturhistorische Museum Wien 85A:135163.
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.
Roopnarine, P. D. 2001. The description and classification of evolutionary mode: a computational approach. Paleobiology 27:446465.
Roopnarine, P. D., Byars, G., and Fitzgerald, P. 1999. Anagenetic evolution, stratophenetic patterns, and random walk models. Paleobiology 25:4157.
Schluter, D. 2000. The ecology of adaptive radiation. Oxford University Press, Oxford.
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.
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.
Sheets, H. D., and Mitchell, C. E. 2001a. Uncorrelated change produces the apparent dependence of evolutionary rate on interval. Paleobiology 27:429445.
Sheets, H. D., and Mitchell, C. E. 2001b. Why the null matters: statistical tests, random walks and evolution. Genetica 112-113:105125.
Simpson, G. G. 1944. Tempo and mode in evolution. Columbia University Press, New York.
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.
Strauch, F. 1968. Determination of Cenozoic sea-temperatures using Hiatella arctica (Linné). Palaeogeography, Palaeoclimatology, Palaeoecology 5:213233.
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.
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.
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.
Thompson, J. N. 1998. Rapid evolution as an ecological process. Trends in Ecology and Evolution 13:329332.
Travis, J. 1989. The role of optimizing selection in natural populations. Annual Review of Ecology and Systematics 20:279296.
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.
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.
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.
Van Voorhies, W. A. 1996. Bergmann size clines: a simple explanation for their occurrence in ectotherms. Evolution 50:12591264.
Walker, J. A. 1998. QuicKurve.∼walker/software.html
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.

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

  • Dana H. Geary (a1), Gene Hunt (a2), Imre Magyar (a1) and Holly Schreiber (a1)


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