The Inheritance of Shell Color in the Land Snail Bradybaena pellucida

Abstract

Bradybaena pellucida exhibits shell color and banding polymorphism. We have found four shell types : yellow-unbanded (YU), yellow-banded (YS), brown-unbanded (BU), and brown-banded (BS), in Tateyama, Chiba. Asami et al. (1993) has shown the genetic dominance of the banded morph to the unbanded. In the present study, we tested the mode of inheritance of the shell color by crossing experiments. The results indicate that the brown allele (C^B) is dominant to the yellow allele (C^y). In a testcross of BS and YU, offspring segregated in two phenotypes, YS and BU. This suggests that loci for shell color and banding are tightly linked and the BS parent was a double-heterozygote with domonant alleles at the trans-position.