|Inheritance of a shell-color polymorphism in the mussel|
Innes, D.J.; Haley, L.E. (1977). Inheritance of a shell-color polymorphism in the mussel. J. Hered. 68: 203-204
In: Journal of Heredity. Oxford University Press: Cary, N.C.. ISSN 0022-1503, more
Cepaea nemoralis (Linnaeus, 1758) [WoRMS]; Mytilus edulis Linnaeus, 1758 [WoRMS]; Marine
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Shell-color polymorphisms are known to exist in several molluscan species. Most studied is probably the land snail, Cepaea nemoralis, which exhibits a few distinct morphs based on shell color and banding pattern'. These visual polymorphisms allow field populations to be characterized by their phenotypic frequencies. Populations from different geographical regions can therefore easily be compared with respect to observed morph frequencies. Such ecological genetic investigations have made a large contribution to the understanding of the mechanisms maintaining population polymorphisms under natural conditions.Using shell-color morphs to study ecological genetics of molluscs implies an underlying genetic basis for the polymorphism. Environmental factors, such as diet, are known to influence shell color7. Circumstantial evidence, such as the color of newly repaired shells, has been used to indicate its genetic determinism4. But the best way to understand the genetics of any character obviously is through selected crosses and observation in the F, generation.Shell color in the common mussel, Mytilus edulis, is predominantly black. The occurrence of a brown form, which actually ranges from pure brown to almost black, except for a small brown patch near the umbone (see cover), has been noted. A striped phenotype was also observed, where brown and black stripes of varying thickness run along the length of the shell. Information on the genetic basis of such a color polymorphism should be easily sorted out by performing the appropriate crosses.