Polymorphism in a West African Snail

Abstract

Limicolaria aurora (Jay), a land snail of Nigeria, is polymorphic for two shell-color characters, banding and background coloration. Banded is dominant to unbanded (the gene U, u) while pink background is dominant to gray (the gene G, g). This polymorphism is probably controlled by two tightly linked genes rather than by a series of alleles at one locus. Evidence is presented that in some populations there is a deficiency of the coupling phase UG/ug, the majority of double heterozygotes being in the repulsion phase (Ug/uG). It is unlikely that selective predation by thrushes and beetle larvae adjusts phenotype frequencies in natural populations.