Associations of enzymic and chromosomal polymorphisms in the seaweed fly, Coelopa frigida

Summary Populations of the seaweed fly Coelopa frigida are polymorphic at three loci determining the enzymes peptidase-1 ( Pep -1), alcohol dehydrogenase ( Adh ) and larval esterase-2 ( Es -2). Alleles at these loci have been shown by others to be non-randomly associated with each other. In the present paper we report non-random associations between the Adh and Es -2 loci and inversions on chromosome I. The two common alleles Adh-B and D are in strong linkage disequilibrium with the α and β inversions, but the Adh-A and C alleles are not so. The X and Y alleles at the Es -2 locus show weak, but still significant, associations with the inversions. We consider possible linkage relationships of the loci on the chromosomal arrangements, and discuss the hypothesis that they constitute part of a coadapted gene complex whose members code for functionally related enzymes.