Studies onCepaeaI. The genetics of some morphs and varieties ofCepaea nemoralis(L.)

Abstract

The following segregants of shell colour are described: pale brown, faint brown, faint pink, yellow-white. Faint pink is dominant to dark and pale yellow and recessive to pale pink. Murray's finding that the hyalozonate gene when homozygous pales shell colour as well as removing the lip and banding pigment is confirmed; faint pink or yellow-white shells homozygous for hyalozonate may be genetically faint pink or pale pink. Deep pink hyalozonates exist and transmit their phenotype to their offspring; in these the paling effect is not noticeable. Shells with no bands but a strip of fascialbate opaque material in the position for bordering the middle band are genetically mid-banded. The condition is due to a multifactorial suppression of the pigmented band. Spread-banded is described in the five-banded form as well as the mid-banded; the strong linkage between it and shell colour previously suggested is confirmed, but crossovers are recorded. White lip (with normally pigmented bands) is recessive to normal lip, linked to the locus for shell-colour, and allelic to hyalozonate. The normal lip/white lip heterozygote appears to be palelipped, but the degree of pallor is modified by the presence of yellow or pink shell colour. White lip, when homozygous, may reduce the intensity of shell colour in some cases, as does hyalozonate. Hyalozonate is shown to be linked to the banding locus, which itself is strongly linked to that for shell colour. Orange-banded is complementary to hyalozonate, not allelic to it as is the very similar form lurida described by Murray in Cepaea hortensis. A form of the var. punctata producing only traces of bands and occasionally a definite punctate band is described, which is linked to the shell colour locus and dominant to normal bands. This and the form figured by Lang and by Taylor with well-developed punctate bands (the segregation of which from normal bands is confirmed) may well be alleles. A segregation of medium grey to very pale body is described, with medium grey dominant to pale. It appears to be unlinked to shell colour, banding and mid-banded.