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Evolution and hybridization in the radiolarian genera Theocorythium and Lamprocyclas

Published online by Cambridge University Press:  08 April 2016

Colin Baker
Colin Baker*
Affiliation:
Museum of Paleontology, University of Michigan, Ann Arbor, Michigan 48109
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Abstract

Changes in morphological variability within fossil populations of planktonic protists provide insight into the processes responsible for morphological change. Evolution in the radiolarian genera Theocorythium and Lamprocyclas is documented biometrically in Pliocene and Pleistocene core material from the equatorial Pacific and Indian Oceans. The patterns of morphological change in Theocorythium within a single Pacific core could be interpreted as indicating the in situ evolution of T. trachelium trachelium from T. vetulum via intermediate forms during the Pleistocene. However, consideration of biogeographic data shows that this is not the case and supports instead two alternate interpretations: (1) immigration coupled with extensive hybridization and introgression, or (2) multiple polymorphs of a single species changing in frequency along a cline. Analyses of evolutionary change in Theocorythium and the closely related genus Lamprocyclas during the Pliocene suggest that hybridization may be a significant factor in the production of new species. Evolutionary models and phylogenetic analyses should consider that barriers to gene flow may vary significantly with time and permit the exchange of genetic information between populations previously reproductively isolated.

Type
Articles
Information
Paleobiology , Volume 9 , Issue 4 , Fall 1983 , pp. 341 - 354
Copyright
Copyright © The Paleontological Society 

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References

Literature Cited

Baker, C. W. and Johnson, D. A. 1982. Evolution and migration in the radiolarian genus Theocorythium. Proc. 3d No. Am. Paleontol. Conv. 1:29–34.Google Scholar
Burckle, L. H. and Opdyke, N. D. 1977. Late Neogene diatom correlations in the Circum-Pacific. Pp. 255–284. In: Saito, T. and Ujue, H., eds. Proc. 1st Int. Cong. Pacific Neogene Stratigraphy. Sci. Council. Japan; Tokyo.Google Scholar
Goll, R. M. 1976. Morphological intergradation between modern populations of Lophospyris and Phormospyris (Trissocyclidae, Radiolaria). Micropaleontology. 22:379–418.CrossRefGoogle Scholar
Grant, V. 1971. Plant Speciation. 435 pp. Columbia Univ. Press, New York.Google Scholar
Hays, J. D. et al. 1969. Plio-Pleistocene sediments of the equatorial Pacific. Geol. Soc. Am. Bull. 80:1481–1513.Google Scholar
Johnson, D. A. and Nigrini, C. 1980. Radiolarian biogeography in surface sediments of the western Indian Ocean. Mar. Micropaleontol. 5:111–152.Google Scholar
Johnson, D. A. and Nigrini, C. 1982. Radiolarian biogeography in surface sediments of the eastern Indian Ocean. Mar. Micropaleontol. 7:237–281.Google Scholar
Kellogg, D. E. 1975. The role of phyletic change in the evolution of Pseudocubus vema (Radiolaria). Paleobiology. 1:359–370.CrossRefGoogle Scholar
Kellogg, D. E. and Hays, J. D. 1975. Microevolutionary patterns in Late Cenozoic Radiolaria. Paleobiology. 1:150–160.Google Scholar
Kennett, J. P. 1976. Phenotypic variation in some Recent and Late Cenozoic planktonic foraminifera. Pp. 1–60. In: Hedley, R. H. and Adams, C. G., eds. Foraminifera 2. Academic Press; London.Google Scholar
Lazarus, D. B. 1983. Speciation in pelagic Protista and its study in the planktonic microfossil record: a review. Paleobiology. 9:327–340.Google Scholar
Lazarus, D. B., Hays, J. D., and Prothero, D. R. 1982. Evolution in the radiolarian species-complex Pterocanium. Proc. 3d No. Am. Paleontol. Conv. 2:323–328.Google Scholar
Lazarus, D. V., Scherer, R. P., and Prothero, D. R.In press. Evolution of the radiolarian species-complex Pterocanium: a preliminary survey. J. Paleo.Google Scholar
Lowrie, W. and Alvarez, W. 1981. One hundred million years of geomagnetic polarity history. Geology. 9:392–397.Google Scholar
Malmgren, B. A. and Kennett, J. P. 1981. Phyletic gradualism in a Late Cenozoic planktonic foraminiferal lineage; DSDP Site 284, southwest Pacific. Paleobiology. 7:230–240.CrossRefGoogle Scholar
Nigrini, C. 1967. Radiolaria in pelagic sediments from the Indian and Atlantic Oceans. Bull. Scripps Inst. Oceanogr. 11:1–106.Google Scholar
Nigrini, C. 1971. Radiolarian zones in the Quaternary of the equatorial Pacific Ocean. Pp. 443–461. In: Funnell, B. M. and Riedel, W. R., eds. The Micropaleontology of Oceans. Cambridge Univ. Press; Cambridge.Google Scholar
Nigrini, C. and Moore, T. C. Jr. 1979. A guide to modern Radiolaria. 260 pp. Cushman Found. Foraminiferal Res. Spec. Pub. 16.Google Scholar
Prell, W., Gardner, J. V., et al. 1980. Preliminary results of DSDP Leg. 68. Geol. Soc. Am. Bull. 91:433–444.2.0.CO;2>CrossRefGoogle Scholar
Riedel, W. R. and Sanfilippo, A. 1977. Cenozoic Radiolaria. Pp. 847–912. In: Ramsay, A. T. S. ed. Oceanic Micropaleontology. Academic Press; New York.Google Scholar
Riedel, W. R. and Sanfilippo, A. 1978. Stratigraphy and evolution of tropical Cenozoic radiolarians. Micropaleontology. 23:61–96.Google Scholar
Shackleton, N. J. and Opdyke, N. D. 1976. Oxygen isotope and paleomagnetic stratigraphy of Pacific core V28-239. Geol. Soc. Am. Mem. 145:449–464.Google Scholar
Szumakow, L. 1982. Radiolarian biostratigraphy of the eastern equatorial Indian Ocean. , Google Scholar