Nature genetic basis and evolution of the haemoblobin polymorphism in Chironomus

Chironomus larvae exhibit considerable haemoblobin polymorphism. Chironomus tnetans has 10 and C. pallidivittatus has 8 electrophoretically different Hb-chains. With the exception of one Hb-chain, all are species-specific. The hybrid which is fertile, shows the Hb-pattern of both parents. In the F2 and subsequent generations, considerable chromosome rearrangements occurs. Since the chromosomes of the parent species can be distinguished in the polytene state, Hb-patterns can be correlated with specific chromosomal constitutions. All the species-specific Hb-genes are located on one chromosome. This finding suggests that the Hb-genes have evolved through multiple gene duplications. Different mechanisms for gene duplication are discussed.