Abstract
A phenotypic study of shell color and molecular variation in the loci glucose-6-phosphate dehydrogenase (G-6-PD) and glucosephosphate isomerase (GPO in the estuarine gastropod Neritina latissima in four populations in the Pacific coast of Puntarenas, Costa Rica, confirmed that the variation in frequencies of the different morphs is regulated through predation. There was no apparent effect of climate or any other environmental factor. Eight polymorphic alleles were detected in G -6 -PD and fourteen in GPI with starch gel electrophoresis. In both cases the allelic frequencies differ among populations, but there are unique variants in each. The average heterozygosity (H) per locus and per population is very high, ranging between 0.76 and 0.82 in G-6-PD and 0.78 to 0.87 in GPI. No apparent association was found between the allozirnic variation and the different phenotypes. Possible evolutionary implications on these results are discussed.References
Ayala, FJ. 1975. Scientific hypotheses, natural selection and the neutrality theory of protein evolution, p. 14-42. In F.M. Salzano, the Role of Natural Selection in Human Evolution. North-Holland, Amsterdam.
Brussard, P.F. 1975. Geographic variation in North American colonies of Cepaea nemoralis. Evolution, 29: 402-410.
Brussard, P. F., & G.F. McCracken. 1974. AlJozymic variation in a North American colony of Cepaea nemoralis. Heredity, 33: 98-101.
Cain, A.J., & P.M. Sheppard. 1954. Natural selection in Cepaea. Genetics, 39: 89-116.
Clarke, A. 1978. Polymorphism in marine mollusks in biome development. Smithsonian Contributions to Zoology 274. 14 p.
Clarke, B. 1975. The contribution of ecological genetics to evolutionary theory: detecting the direct effects of natural selection of particular polymorphic loci. Genetics, 79: 101-113.
Dobzhansky, T., F, J. Ayala, G.L. Stebbins, & J.W. Valentine. 1977. Evolution. Freeman, San Francisco, 572 p.
Ford, E.B. 1971. Ecological Genetics. Chapman and Hall, London 410 p.
Harris, H., & D.A. Hopkinson. 1976. Handbook of Enzyme Electrophoresis in Human Genetics. North-Holland, Amsterdam.
Johnson, M.S. 1976. Allozymes and area effects in Cepaea nemoralis on the Western Berkshire downs. Heredity, 36: 105-121.
Johnson, M.S., B. Clarke, & J. Murray. 1977. Genetic variation and reproductiive isolation in Partula. Evolution, 31: 116-126.
Keen, A.M. 1971. Sea Shells of Tropical West America. Stanford University Press, Calif. 1064 p.
Kirnura, M. 1968. Genetic variability maintained in a finite population due to mutational production of neutral and nearly neutral isoalleles. Genet. Res., 11: 247-269.
Kirnura, M., & Tomoko Ohta. 1974. On sorne principies governing molecular evolution. Proc. Natl. Acad. Sci. U.S.A. 71: 2848-2852.
Koehn, R. K, R. Milkarn, & J. Mitton. 1976. Populations genetics of marine pelecypods. IV Selection, migration and genetic differentiation in the blue mussel Mytilus edulis. Evolution, 30: 2-32.
Levan, G., & K. Fredga. 1972. Isozyme polymorphism in three species of land smails. Hereditas, 71: 245-252.
Lewontin, R.C. 1974. The Genetic Basis of Evolutionary Change. Columbia University Press. 346 p.
Lewontin, R.C., & J.L. Hubby. 1966. A molecular approach to the study of genic heterozigosity in natural populations. II. Amount of variation and degree of heterozygosity in natural populations of Drosophila pseudoobscura. Genetics, 54: 595-609.
Nei, M., T. Maruyarna, & R. Chakraborty. 1975. The bottleneck effect and genetic variability in populations. Evolution, 29: 1-10.
Nevo, E. 1978. Genetic variation in natural p opulations: patterns and theory. Theor. Pop. Biol., 13(1): 121-177.
Selander, R.K. 1976. Genic variation in natural p opulations, p. 21-45 . In F.J. Ayala, Molecular Evolution. Sinauer, Mass. 277 p.
Selander, R.K., & D. Kaufman. 1973. Self fertilization and genetic population structure in a colonizing land snail. Proc. Nat. Acad. Sci. USA. 70 (4): 1186-1190.
Valdez, Marta. 1979. Variación en poblaciones naturales de Neritina latissima (Gastropoda: Neritidae) en Costa Rica. Tesis. Sistema de Estudios de Posgrado, Universidad de Costa Rica, 98 p.
Valdez, Marta, & J.A. Briceño. 1980. Incorporación de manganeso en Neritina latissima (Gastropoda: Neritidae) en Costa Rica. Rev. Biol. Trop., 28: 175-180.
Comments
![Creative Commons License](http://i.creativecommons.org/l/by/4.0/88x31.png)
This work is licensed under a Creative Commons Attribution 4.0 International License.
Copyright (c) 1980 Revista de Biología Tropical