Effect of Temperature on the Selective Value of Genotypes of the Copepod Tisbe reticulata

Abstract

IN the Lagoon of Venice, the harpacticoid copepod Tisbe reticulata shows a striking polychromatism which is controlled by three alleles at the same locus, V^V, V^M and v. The first two, dominant over the common recessive v, are responsible for the forms violacea and maculata, respectively, whereas the homozygote vv is responsible for the form trifasciata. The alleles V^V and V^M are co-dominant and therefore the heterozygote V^V V^M is phenotypically recognizable. It has been shown that this polymorphism is adaptive and balanced, and, in most cases, maintained by the greater survival value of the heterozygotes compared with the homozygotes¹.