Linkage disequilibrium between functionally related enzyme loci of Drosophila mojavensis.

Gametic frequencies at four enzyme loci of the second chromosome of Drosophila mojavensis race B were obtained from six localities. The four loci were selected so that they code for functionally related enzymes; two code for esterases, one for xanthine dehydrogenase and one for acetaldehyde oxidase. In Drosophila the two latter enzymes are under the same regulatory control and their physiological functions might be related as well. Electrophoretic variants at the locicoding for these two enzymes were found not tobe in pair-wise linkage equilibrium. Other pair-wise combinations were in linkage equilibrium. It is argued that selectively maintained nonrandom associations may occur frequently between linked loci, the enzymatic products of which are functionally related, share common subunits or are under the same regulatory control.