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Heterochronic Dimorphism of Loxoconcha Uranouchiensis (Ostracoda) and its Implication for Speciation

Published online by Cambridge University Press:  08 April 2016

Takahiro Kamiya*
Affiliation:
Department of Earth Sciences, Kanazawa University, 1-1 Marunouchi, Kanazawa 920, Japan

Abstract

Polymorphism is being actively investigated by ostracode specialists because the phenomenon is widespread and may be a key to understanding speciation patterns and evolutionary processes. However, the methods for recognizing the phenomenon and the cause or causes of polymorphism are still under debate. This study presents an example of genetically controlled ostracode dimorphism in which the relationship between the two forms can be explained in terms of heterochrony. The living males as well as the females of Loxoconcha uranouchiensis in Aburatsubo Cove, central Japan, are found to be dimorphic in size, shape, and surface ornamentation of the carapace. The dimorphic forms appear concurrently in the same microhabitat, suggesting that the dimorphism is genetically rather than environmentally controlled. Although the large and the small forms are indistinguishable in their early stages, morphological differences gradually appear and become complete after the final molting, which is the seventh molting for both forms. The characters determined by the number of moltings, such as the numbers of reticules, bristles, and pores, are identical between adults of the two forms. In contrast, for characters affected by the growth condition of the epidermal-cell system, such as carapace shape and fine surface ornamentation, the small-form adult is similar to the penultimate instar of the large form. Taking the large form as a standard, the small form is paedomorphic. These two forms are reproductively isolated and should be considered different species.

Type
Research Article
Copyright
Copyright © The Paleontological Society 

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References

Literature Cited

Abe, K. 1988. Speciation completed? in Keijella bisanensis species group. Pp. 919925in T. Hanai et al., eds. 1988.Google Scholar
Abe, K., Reyment, R. A., Bookstein, F. L., Honigstein, A., Almogi-Labin, A., Rosenfeld, A., and Hermelin, O.. 1988. Microevolution in two species ostracods from the Santonian (Cretaceous) of Israel. Historical Biology 1: 303322.Google Scholar
Benson, R. H. 1976. The evolution of the ostracode Costa analyzed by “Theta-Rho Difference.” Pp. 127139In Hartmann, G., ed. 1976.Google Scholar
Bertels, A. 1976. Evolutionary lineages of some Upper Cretaceous and Tertiary ostracodes of Argentina. Pp. 175190In Hartmann, G., ed. 1976.Google Scholar
Carbonel, P., and Hoibian, T.. 1988. The impact of organic matter on ostracods from an equatorial deltaic area, the Mahakam Delta—Southeastern Kalimantan. Pp. 353366in T. Hanai et al., eds. 1988.Google Scholar
Cronin, T. M. 1988. Geographical isolation in marine species: evolution and speciation in Ostracoda, I. Pp. 871889In Hanai, T. et al., eds. 1988.Google Scholar
Cronin, T. M., and Schmidt, N.. 1988. Evolution and biogeography of Orionina in the Atlantic, Pacific and Caribbean: evolution and speciation in Ostracods, II. Pp. 927938In Hanai, T. et al., eds. 1988.Google Scholar
Danielopol, D. L., Geige, W., Tölderer-Farmer, M., Orellana, C. P., and Terrat, M.-N.. 1988. In search of Cypris and Cythere: a report of the evolutionary ecological project on limnic Ostracoda from the Mondsee (Austria). Pp. 485500In Hanai, T. et al., eds. 1988.Google Scholar
Ducasse, O., Lete, C., and Rousselle, L.. 1988. Polymorphism and speciation: Medoc ostracods at the Eocene/Oligocene boundary (Aquitaine, France). Pp. 939947In Hanai, T. et al., eds. 1988.Google Scholar
Elofson, O. 1941. Zur Kenntnis der marinen Ostracoden Schwedens mit besonderer Berücksichtigung des Skageraks. Zoologica Bidrag Fran Uppsala 19: 215534.Google Scholar
Frydl, P. M. 1982. Holocene ostracods in the Southern Boso Peninsula. Pp. 61140In Hanai, T., ed. 1982.Google Scholar
Gramm, M. N. 1985. The muscle scar in cavellinids and its importance for the phylogeny of platycope ostracodes. Lethaia 18: 3952.Google Scholar
Hanai, T., ed. 1982. Studies on Japanese Ostracoda. University of Tokyo Press, Tokyo.Google Scholar
Hanai, T., Ikeya, N., and Ishizaki, K., eds. 1988. Evolutionary biology of Ostracoda, its fundamentals and applications. Proceedings of the Ninth International symposium on Ostracoda. Shizuoka, Japan. July 29-August 2, 1985. Kodansha, Tokyo.Google Scholar
Hartmann, G., ed. 1976. Evolution of post-Paleozoic Ostracoda. Paul Prey, Hamburg.Google Scholar
Ikeya, N., and Hanai, T.. 1982. Ecology of Recent ostracods in the Hamana-ko region, the Pacific coast of Japan. Pp. 1559In Hanai, T., ed. 1982.Google Scholar
Ikeya, N., and Ueda, H.. 1988. Morphological variations of Cytheromorpha acupunctata (Brady) in continuous populations at Hamana-ko Bay, Japan. Pp. 319340In Hanai, T. et al., eds. 1988.Google Scholar
Ishizaki, K. 1968. Ostracodes from Uranouchi Bay, Kochi Prefecture, Japan. Science Reports of the Tohoku University, Sendai, Second Series (Geology) 40: 145.Google Scholar
Ishizaki, K. 1969. Ostracodes from Shinjiko and Nakanoumi, Shimane Prefecture, western Honshu, Japan. Science Reports of the Tohoku University, Sendai, Second Series (Geology) 41: 197224.Google Scholar
Ishizaki, K. 1971. Ostracodes from Aomori Bay, Aomori Prefecture, Northeast Honshu, Japan. Science Reports of the Tohoku University, Sendai, Second Series (Geology) 43: 5997.Google Scholar
Ishizaki, K. 1981. Ostracoda from the East China Sea. Science Reports of the Tohoku University, Sendai, Second Series (Geology) 51: 3765.Google Scholar
Kaesler, R. L., and Lohmann, K. C.. 1976. Phenotypic variations of populations of Krithe producta with environment. Pp. 279285In Hartmann, G., ed. 1976.Google Scholar
Kamiya, T. 1988a. Morphological and ethological adaptations of Ostracoda to microhabitats in Zostera beds. Pp. 303318In Hanai, T. et al., eds. 1988.Google Scholar
Kamiya, T. 1988b. Different sex-ratios in two Recent species of Loxoconcha (Ostracoda). Senckenbergiana Lethaea 68: 337345.Google Scholar
Kamiya, T. 1988c. Contrasting population ecology of two species of Loxoconcha (Ostracoda, Crustacea) in Recent Zostera (eelgrass) beds: adaptive differences between phytal and bottom-dwelling species. Micropaleontology 34: 316331.CrossRefGoogle Scholar
Kamiya, T. 1989. Differences between sensory organs of phytal and bottom-dwelling Loxoconcha (Ostracoda, Crustacea). Journal of Micropalaeontology 8: 3747.Google Scholar
Keen, M. C. 1976. An evolutionary study of two homeomorphic Tertiary Cytherid ostracod genera. Pp. 319323In Hartmann, G., ed. 1976.Google Scholar
Keen, M. C. 1982. Intraspecific variation in Tertiary ostracods. Pp. 381405In Bate, R. H., Robinson, E., and Sheppard, L. M., eds. Fossil and Recent ostracods. Ellis Horwood, Chichester, England.Google Scholar
Kilenyi, T. I. 1972. Transient and balanced genetic polymorphism as an explanation of variable noding in the ostracode Cyprideis torosa. Micropaleontology 18: 4763.Google Scholar
Majima, R. 1985. Intraspecific variation in three species of Glossaulax (Gastropoda: Naticidae) from the Late Cenozoic Strata in central and southwest Japan. Transactions and Proceedings of the Palaeontological Society of Japan, New Series 138: 111137.Google Scholar
Maness, T. R., and Kaesler, R. L.. 1987. Ontogenetic changes in the carapace of Tyrrhenocythere amnicola (Sars) a Hemicytherid ostracode. University of Kansas Paleontological Contributions Paper 18: 115.Google Scholar
McNamara, K. J. 1983. Progenesis in tribobites. Pp. 5968in Briggs, D.E.G. and Lane, P. D., eds. Trilobites and other arthoropods: papers in honour of H. B. Whittington, F. R. S. Special Papers in Palaeontology 31.Google Scholar
McNamara, K. J. 1986. A guide to the nomenclature of heterochrony. Journal of Paleontology 60: 413.Google Scholar
McNamara, K. J. 1987. Taxonomy, evolution, and functional morphology of southern Australian Tertiary hemiasteroid echinoids. Palaeontology 30: 319352.Google Scholar
Nohara, T. 1987. Cenozoic ostracodes of Okinawa-jima. Bulletin of the College of Education, University of the Ryukyus no. 30 (3):1105.Google Scholar
Oertli, H. J. 1976. The evolution of Loculicytheretta in the Eocene. Pp. 153160In Hartmann, G., ed. 1976.Google Scholar
Okada, Y. 1981. Development of cell arrangement in ostracod carapaces. Paleobiology 7: 276280.Google Scholar
Okubo, I. 1980. Taxonomic studies on Recent marine podocopid Ostracoda from the Inland Sea of Seto. Publication of the Seto Marine Biological Laboratory XXV: 389443.Google Scholar
Olempska, E. 1989. Gradual evolutionary transformations of ontogeny in an Ordivician ostracod lineage. Lethaia 22: 159168.Google Scholar
Peypouquet, J. P., Carbonel, P., Ducasse, O., Tölderer-Farmer, M., and Lete, C.. 1988. Environmentally cued polymorphism of ostracods—a theoretical and practical approach. A contribution to geology and to the understanding of ostracod evolution. Pp. 10031019In Hanai, T. et al., eds. 1988.Google Scholar
Ramskold, L. 1988. Heterochrony in Silurian phacopid trilobites as suggested by the ontogeny of Acernapsis. Lethaia 21: 307318.Google Scholar
Reyment, R. A. 1985. Phenotypic evolution in a lineage of the Eocene ostracod Echinocythereis. Paleobiology 11: 174194.Google Scholar
Reyment, R. A. 1988. Evolutionary significant polymorphism in marine ostracods. Pp. 9871001In Hanai, T. et al., eds. 1988.Google Scholar
Sandberg, P. A. 1964. The ostracod genus Cyprideis in the Americas. Stockholm Contributions in Geology 12: 1178.Google Scholar
Schornikov, E. I. 1988. The concept of cyclicity of morphogenesis. Pp. 195205In Hanai, T. et al., eds. 1988.Google Scholar
Schweitzer, P. N., Kaesler, R. L., and Lohmann, G. P.. 1986. Ontogeny and heterochrony in the ostracode Cavellina Coryell from Lower Permian rocks in Kansas. Paleobiology 12: 290301.Google Scholar
Sylvester-Bradley, P. C., and Benson, R. H.. 1971. Terminology for surface features in ornate ostracodes. Lethaia 4: 249286.Google Scholar
Szczechura, J. 1971. Seasonal change in a reared fresh-water species. Cyprinotus (Heterocypris) incogruens (Ostracoda), and their importance in the interpretation of variability in fossil Ostracodes. Pp. 191205In Oertli, H. J., ed. Colloque sur la paleoecologie des ostracodes. Pau, France, July 20-27, 1970. Bulletin du Centre de Recherches Pau-SNPA, Vol. 5 (Supplement) Pau.Google Scholar
Tabuki, R., and Nohara, T.. 1988. Preliminary study on the ecology of ostracods from the moat of a coral reef off Sesoko Islands, Okinawa, Japan. Pp. 429437In Hanai, T. et al., eds. 1988.Google Scholar
Tabuki, R., Nakano, T., and Nohara, T.. 1987. Preliminary report on ostracode fauna from Sekisei-sho Area, Yaeyama Islands. Bulletin of College of Education, University of the Ryukyus.Google Scholar
Tschanz, K. 1988. Allometry and heterochrony in the growth of the neck of Triassic Prolacertiform reptiles. Palaeontology 31: 9971011.Google Scholar
Tsukagoshi, A., and Ikeya, N.. 1987. The ostracod genus Cythere O. F. Müller, 1785 and its species. Transactions and Proceedings of the Palaeontological Society of Japan, New Series 148: 197222.Google Scholar
Whatley, R. C., Harlow, C. J., Dowing, S. E., and Kesler, K. J.. 1983. Observations on the origin, evolution, dispersion and ecology of the genera Poseidonamicus Benson and Bradleya Hornibrook. Pp. 492509In Maddocks, R. F., ed. Application of Ostracoda. The Department of Geosciences, University of Houston-University Park, Houston, Tex.Google Scholar
Yajima, M. 1978. Quaternary Ostracoda from Kisarazu near Tokyo. Transactions and Proceedings of the Palaeontological Society of Japan, New Series 112: 371409.Google Scholar
Yajima, M. 1982. Late Pleistocene Ostracoda from the Boso Peninsula, central Japan. Pp. 141227In Hanai, T., ed. 1982.Google Scholar