Abstract
Gene-enzyme variation was studied electrophoretically within and between barnacle populations of the genus Chthamalus from 8 intertidal stations from central California to the Pacific coast of Panamá. Horizontal starch-gel electrophoresis separated and resolved 18 enzymes from 512 individual barnacles. A maximum of 25 gene-enzyme systems was interpretable from the resulting zymograms. Electrophoretic phenotypes and patterns of phenotypic variation generally conformed with those observed in other organisms. The amount of genetic variation within barnacle populations varied; average heterozygosity, for example, ranged from a low of 3.4% in a Mexican population of the C. fissus group to a high of 10.4% in C. anisopoma from the Gulf of California. Observed and expected average heterozygosities agreed in all population samples, indicating that these species are outbreeding. In contrast to the prediction stemming from a hypothesis that trophic stability regulates the amount of genetic variation in marine species, average heterozygosity tends to be positively correlated with latitude. Data from these and other barnacle species may support a hybrid “environmental heterogeneity-trophic diversity” model recently proposed to explain genetic variation in decapod crustaceans. Juxtaposition of individuals from different localities revealed numerous genetic differences among populations of the C. fissus group. At least three partially sympatric sibling species are separated by genetic distances as large as those observed between the C. fissus group and the distinct species C. dalli and C. anisopoma. A cladistic analysis places C. anisopoma close to the Mexican and Panamanian sibling species, with C. fissus from San Diego and C. dalli successively farther removed.
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Literature Cited
Anderson, D.T.: Cirral activity and feeding in the coral-inhabiting barnacle Boscia anglica (Cirripedia). J. mar. biol. Ass. U.K. 58, 607–626 (1978)
Avise, J.C.: Systematic value of electrophoretic data. Syst. Zool. 23, 467–481 (1974)
Ayala, F.J.: Genetic differentiation during the speciation process. In: Evolutionary biology, Vol. 8. pp 1–78. Ed. by T. Dobzhansky, M.K. Hecht and W.C. Steere. New York: Plenum Press 1975
—, D. Hedgecock, G. Zumwalt and J.W. Valentine: Genetic variation in Tridacna maxima, an ecological analog of some unsuccessful evolutionary lineages. Evolution, Lawrence, Kansas 27, 177–191 (1973)
— and J.R. Powell: Allozymes as diagnostic characters of sibling species of Drosophila. Proc. natn. Acad. Sci. U.S.A. 69, 1094–1096 (1972)
Barnes, H. and M. Barnes: Further observations on self-fertilization in Chthamalus spp. Ecology 39, p. 550 (1958)
Dando, P.R., A.J. Southward and D.J. Crisp: Enzyme variation in Chthamalus montagui (Crustacea: Cirripedia): evidence for the presence of C. montagui in the Adriatic. J. mar. biol. Ass. U.K. 59, 307–320 (1979)
Farris, J.S.: Methods for computing Wagner trees. Syst. Zool. 19, 83–92 (1970)
Gillespie, J.H. and K. Kojima: The degree of polymorphism in enzymes involved in energy production compared to that in non-specific enzymes in two Drosophila ananassae populations. Proc. natn. Acad. Sci. U.S.A. 61, 582–585 (1968)
Gottlieb, L.D.: Gel electrophoresis: new approach to the study of evolution. BioSci. 21, 939–944 (1971)
Harris, H. and D.A. Hopkinson: Handbook of enzyme electrophoresis in human genetics, 259 pp. New York: American Elsevier Publishing Co., Inc. 1976
Juan, E.: Polimorfismo enzymatico en poblaciones de Chthamalus stellatus y C. depressus (Crustacea, Cirripedia). Oecologia aquat. (Dep. Ecologia, Facultad de Biologia, Universidad de Barcelona) 2, 111–119 (1976)
Levene, H.: On a matching problem arising in genetics. Ann. math. Statist. 20, 91–94 (1949)
Levins, R.: Evolution in changing environments, 120 pp. Princeton, New Jersey: Princeton University Press 1968
Manwell, C. and C.M.A. Baker: Molecular biology and the origin of species, 394 pp. Seattle: University of Washington Press 1970
Nei, M.: Interspecific gene differences and evolutionary time estimated from electrophoretic data on protein identity. Am. Nat. 105, 385–398 (1971)
—: Genetic distance between populations. Am. Nat. 106, 283–292 (1972)
Nelson, K. and D. Hedgecock: Enzyme polymorphism and adaptive strategy in the decapod Crustacea. Am. Nat. (In press). (1979)
Nevo, E., T. Shimony and M. Libni: Thermal selection of allozyme polymorphisms in barnacles. Nature, Lond. 267, 699–701 (1977)
Sneath, P.H.A. and R.R. Sokal: Numerical taxonomy — the principles and practice of numerical classification, 573 pp. San Francisco: W.H. Freeman & Co. 1973
Southward, A.J.: Intertidal and shallow water Cirripedia of the Caribbean. Stud. Fauna Curaçao 46, 1–53 (1975)
— and W.A. Newman: Aspects of the ecology and biogeography of the intertidal and shallow-water balanomorph Cirripedia of the Caribbean and adjacent sea-areas. FAO Fish. Rep. 200, 407–426, FIR/R(E/Es) (1977)
Tracey, M.L., K. Nelson, D. Hedgecock, R.A. Shleser and M.L. Pressick: Biochemical genetics of lobsters (Homarus): genetic variation and the structure of American lobster populations. J. Fish. Res. Bd Can. 33, 1108–1119 (1975)
Valentine, J.W.: Genetic strategies of adaptation. In: Molecular evolution, pp 78–94. Ed. by F.S. Ayala. Sunderland, Massachusetts: Sinauer Associates 1976
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Communicated by N.D. Holland, La Jolla
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Hedgecock, C. Biochemical genetic variation and evidence of speciation in Chthamalus barnacles of the tropical eastern Pacific Ocean. Mar. Biol. 54, 207–214 (1979). https://doi.org/10.1007/BF00395782
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DOI: https://doi.org/10.1007/BF00395782