The genetics of some polymorphic Esterases in Drosophila simulans

Analysis of strains of Drosophila simulans derived from a natural population in Turkey has shown that three alleles at the Esterase-6 locus are present in some strains. These alleles produce allozymes with mobilities equivalent to other esterases coded for by three other loci, one of which () is tightly linked to Esterase-6. Active alleles at all these loci are present at low frequencies. The presence of the active allele at the locus in laboratory strains in absolutely correlated with the presence of the Esterase 6 ^-3 allele and strong linkage disequilibrium between these two loci exists.It appears possible that the origin of one or more of these hitherto unremarked loci, whose active alleles are expressed only in females, lies in gene duplication, coupled with the action of selection in an environment thought to be heavily