Abstract
Samples from the high and low shore were taken from mussel populations at two localities. Croyde Bay and Whitsand Bay in southwest England, within the zone of hybridisation of Mytilus edulis and Mytilus galloprovincialis, and analysed at five polymorphic allozyme loci.
Strong correlations were observed between shell length and allele frequencies at both localities, with a higher frequency of alleles characterising M. galloprovincialis being found in larger mussels. Three hypotheses were considered as explanation of these results (1) differential mortality, (2) differential growth and (3) historical change within the hybrid zone. The last hypothesis was rejected because the pattern of length dependent allozyme variation was similar in samples taken in 1980–81 and 1986–87. The observation of small growth differences between M. edulis and M. galloprovincialis provided evidence against the second hypothesis. Thus, higher mortality of younger M. edulis was favoured as the cause of the length-dependent variation. Wave exposure and sand abrasion experienced by the mussels were thought to be the most likely selective factors.
Strong correlations were also observed in these populations between shell length and allozyme heterozygosity. Analysis of genotype frequencies in small and large size classes of mussels provide evidence of a small added effect of heterozygosity, but no evidence of overdominance.
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References
Ahmad, M, and Beardmore, J A. 1976. Genetic evidence that the “Padstow Mussel” is Mytilus galloprovincialis. Marine Biology, 35, 139–147.
Ahmad, M, Skibinski, D O F, and Beardmore, J A. 1977. An estimate of the amount of genetic variation in the common mussel Mytilus edulis. Biochemical Genetics, 15, 833–846.
Avise, J C, and Smith, M H. 1974. Biochemical genetics of sunfish I. Geographic variation and subspecific intergradation in the bluegill, Lepomis macrochirus. Evolution, 28, 42–56.
Beaumont, A R, Beveridge, C M, and Budd, M D. 1983. Selection and heterozygosity within single families of the mussel Mytilus edulis (L.). Marine Biology Letters, 4, 151–161.
Beaumont, A R, Day, T R, and Gade, G. 1980. Genetic variation at the octopine dehydrogenase locus in the adductor muscle of Cerastoderma edule (L.) and six other bivalve species. Marine Biology Letters, 1, 137–148.
Blackwell, J M, and Bull, C M. 1978. A narrow hybrid zone between two Western Australian frog species Ranidella insignifera and R. pseudinsignifera: the extent of introgression. Heredity, 40, 14–25.
Boyer, J F. 1974. Clinal and size-dependent variation at the LAP locus in Mytilus edulis. Biological Bulletin, 147, 535–549.
Colgan, D J. 1981. Spatial and temporal variation in the genotypic frequencies of the mussel Brachidontes rostratus. Heredity, 46, 197–208.
Diehl, W J, and Koehn, R K. 1985. Multiple-locus heterozygosity, mortality and growth in a cohort of Mytilus edulis. Marine Biology, 88, 265–271.
Falconer, D S. 1981. Introduction to Quantitative Genetics. 2nd edn. Longman, London, 340 pp.
Foltz, D W, and Chatry, M. 1986. Genetic heterozygosity and growth rate in Louisiana oysters (Crassostrea virginica). Aquaculture, 57, 261–269.
Gaffney, P M, and Scott, T M. 1984. Genetic heterozygosity and production traits in natural and hatchery populations of bivalves. Aquaculture, 42, 289–302.
Gosling, E M. 1984. The systematic status of Mytilus galloprovincialis in western Europe: A review. Malacologia, 25, 551–568.
Gosling, E M, and Wilkins, N P. 1981. Ecological genetics of the mussels Mytilus edulis and Mytilus galloprovincialis on Irish coasts. Marine Ecology Progress Series, 4, 221–227.
Grant, W S, and Cherry, M I. 1985. Mytilus galloprovincialis Lmk in southern Africa. Journal of Experimental Marine Biology and Ecology, 90, 179–191.
Hawkins, A J S, Bayne, B L, and Day, A J. 1986. Protein turnover, physiological energetics and heterozygosity in the blue mussel, Mytilus edulis: the basis of variable age-specific growth. Proceedings of the Royal Society, London, Series B, 119, 161–176.
Hunt, W G, and Selander, R K. 1973. Biochemical genetics of hybridisation in European house mice (Mus musculus). Heredity, 31, 11–33.
Koehn, R K, and Gaffney, P M. 1984. Genetic heterozygosity and growth rate in Mytilus edulis. Marine Biology, 82, 1–7.
Koehn, R K, Milkman, R, and Mitton, J B. 1976. Population genetics of marine pelecypods. IV. Selection, migration and genetic differentiation in the blue mussel Mytilus edulis. Evolution, 30, 2–32.
Koehn, R K, Hall, J G, Innes, D J, and Zera, A J. 1984. Genetic differentiation of Mytilus edulis in eastern North America. Marine Biology, 79, 117–126.
Lewis, J R, and Seed, R. 1969. Morphological variation in Mytilus from south-west England in relation to the occurrence of Mytilus galloprovincialis (Lmk). Cahiers de biologie marine, 10, 231–253.
Mallet, A L, Zouros, E, Gartner-Kepay, K E, and Freeman, K R. 1986. Genetics of growth in blue mussels: family and enzyme heterozygosity effects. Marine Biology, 92, 475–482.
Milkman, R, and Koehn, R K. 1977. Temporal variation in the relationship between size, numbers, and an allele-frequency in a population of Mytilus edulis. Evolution, 31, 103–115.
Mitton, J M, and Grant, M C. 1984. Association among heterozygosity, growth rate and developmental homeostasis. Annual Review of Ecological Systematics, 15, 479–499.
Moore, M N, Koehn, R K, and Bayne, B L. 1980. Leucine aminopeptidase (aminopeptidase-I), N-acetyl-β-hexoseaminadase and lysomes in the mussel Mytilus edulis L., in response to salinity changes. Journal of Experimental Zoology, 214, 239–249.
Nei, M. 1972. Genetic distance between populations. American Naturalist, 106, 283–292.
Rodhouse, P G, Mcdonald, J H, Newell, R I E, and Koehn, R K. 1986. Gamete production, somatic growth and multiple-locus enzyme heterozygosity in Mytilus edulis. Marine Biology, 90, 209–214.
Seed, R. 1971. A physiological and biochemical approach to the taxonomy of Mytilus edulis L. and Mytilus galloprovin-cialis Lmk from south-west England. Cahiers de biologie marine, 12, 291–322.
Skibinski, D O F. 1983. Natural selection in hybrid mussel populations. In Oxford, G. S. and Rollinson, D. (eds) Protein polymorphism: Adaptive and Taxonomic Significance. Systematics Association Special Volume No. 24, Academic Press, London and New York.
Skibinski, D O F, and Beardmore, J A. 1979. A genetic study of intergradation between Mytilus edulis and Mytilus galloprovincialis. Experientia, 35, 1442–1444.
Skibinski, D O F, Ahmad, M, and Beardmore, J A. 1978a. Genetic evidence for naturally occurring hybrids between Mytilus edulis and Mytilus galloprovincialis. Evolution, 32, 354–364.
Skibinski, D O F, Beardmore, J A, and Ahmad, M. 1978b. Genetic aids to the study of closely related taxa of the genus Mytilus. In Battaglia, B. and Beardmore, J. A. (eds) Marine Organisms: Genetics, Ecology and Evolution, New York and London: Plenum Press, pp. 469–485.
Skibinski, D O F, Beardmore, J A, and Cross, T F. 1983. Aspects of the population genetics of Mytilus (Mytilidae: Mollusca) in the British Isles. Biological Journal of the Linnean Society, 19, 137–183.
Skibinski, D O F, Cross, T F, and Ahmad, M. 1980. Electrophoretic investigation of systematic relationships in the marine mussels Modiolus modiolus L., Mytilus edulis L., and Mytilus galloprovincialis Lmk. (Mytilidae:Mollusca). Biological Journal of the Linnean Society, 13, 65–73.
Zouros, E, and Foltz, D W. 1987. The use of allelic isozyme variation for the study of heterosis. In Rattazzi, M. C, Scandalios, J. G. and Whitt, G. C. (eds) Isozymes: current topics in biological and medical research, 13, 1–59.
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Gardner, J., Skibinski, D. Historical and size-dependent genetic variation in hybrid mussel populations. Heredity 61, 93–105 (1988). https://doi.org/10.1038/hdy.1988.94
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DOI: https://doi.org/10.1038/hdy.1988.94
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