EVOLUTIONARY HISTORY OF DROSOPHILA-BUZZATII .32. LINKAGE DISEQUILIBRIUM BETWEEN ALLOZYMES AND CHROMOSOME INVERSIONS IN 2 COLONIZING POPULATIONS

Chromosome polymorphism in Drosophila buzzatii is under selection but the genes responsible for the effect of the inversions on fitness are unknown. On the other hand, there is evidence for selection on several allozyme loci but the presence of paracentric inversions on the secon d chromosome, where most of-the polymorphic loci are located, complica tes the interpretation. Studies of the associations between allozymes and inversions are thus necessary to help understand the effect of sel ection at both the chromosomal and allozymic level. Until now this kin d of information has only been available in D. buzzatii for two loci, Est-1 and Est-2, in Australian populations. Here we describe the genet ic constitution of two Old World populations, Carboneras and Colera. E mphasis has been placed on the analysis of the linkage disequilibria b etween the second chromosome arrangements and three allozyme loci, Est -2, Pept-2 and Aldox, located on this chromosome. In addition, the rec ombination frequencies between the loci, and between the loci and the inversion breakpoints, have been estimated and a genetic map of the th ree loci has been produced. The two populations differ in allele and a rrangement frequencies, as well as in the pattern of one-locus disequi libria. Est-2 and Alder are associated with the second chromosome arra ngements in both populations. On the other hand, Pept-2 is associated with the inversions in Colera but not in Carboneras. The gametic assoc iations among the three loci are discussed taking into account the pos ition of these loci on the chromosome map and the lack of recombinatio n in the heterokaryotypes.