Enzyme null alleles in natural populations of Drosophila melanogaster: Frequencies in a North Carolina population.

A Raleigh, NC, population of Drosophila melanogaster was sampled for the presence of enzyme null alleles at 25 loci. No nulls were found at any of five X-linked loci. Nulls were recovered at 13 of 20 autosomal loci; the weighted mean frequency for all 20 autosomal loci was estimated to be 0.0025. A consideration of the effects of these null alleles on viability strongly suggests that, although they may contribute to so-called polygenic variation, they are not representative of the entire genome.