Alcohol dehydrogenase and sn-glycerol-3-phosphate dehydrogenase null activity alleles in natural populations of Drosophila melanogaster

Alcohol dehydrogenase (Adh) null activity alleles have been detected in each of 2 years in Australian populations of D. melanogaster at frequencies up to 3·9 per cent, but with an average of 1·3 per cent in 1983 and 0·7 per cent in 1984. In the same populations the frequency of sn-glycerol-3-phosphate dehydrogenase (Gpdh) null alleles was as high as 2·7 per cent with an average of 1·6 per cent in 1983 and 0·5 per cent in 1984. These values compare with previously reported frequencies of 0·09 per cent for Adh and 0·8 per cent for Gpdh in a North Carolina (U.S.A.) and a London (U.K.) population. Of the 12 second chromosomes bearing Adh null alleles, four were homozygous lethal, but all were viable and fertile in combination with Df(2L)64j .