A NEW MODEL OF LATERAL PLATE MORPH INHERITANCE IN THE THREESPINE STICKLEBACK, GASTEROSTEUS-ACULEATUS

The threespine stickleback, Gasterosteus aculeatus, is polymorphic for the arrangement of lateral bony plates. It is confirmed in this paper that four morphs (not three) should be distinguished in this species: low plated, low plated with a keel, partially plated and completely plated. A new model is proposed to explain the inheritance of these morphs which involves one major gene with three alleles displaying a dominance hierarchy with A (completely plated) dominant to a (low plated) which is dominant to a(k) (low plated with keel). The dominance of the A allele is modified to semidominance by a dominant allele C at a second locus. This scheme explains al the results of relevant breeding experiments published so far. Field data also fulfill predictions derived from this model.