Persistence Time Of Loss-Of-Function Mutations At Non-Essential Loci Affecting Eye Color In Drosophila melanogaster

Persistence time of a mutant allele, the expected number of generations before its elimination from the population, can be estimated as the ratio of the number of segregating mutations per individual over the mutation rate per generation. We screened two natural populations of Drosophila melanogaster for mutations causing clear-cut eye phenotypes and detected 25 mutant alleles, falling into 19 complementation groups, in 1164 haploid genomes, which implies 0.021 eye mutations per genome. The de novo haploid mutation rate for the same set of loci was estimated as 2*10^-4 in a 10-generation mutation-accumulation experiment. Thus, the average persistence time of all mutations causing clear-cut eye phenotypes is ~100 generations (95% confidence interval: 61-219). This estimate shows that the strength of selection against phenotypically drastic alleles of non-essential loci is close to that against recessive lethals. In both cases, deleterious alleles are apparently eliminated at heterozygous state, where they lack overt phenotypic manifestation.

Key Words: Drosophila, eye phenotypes, mutation rate, persistence time, selection

Online ISS 1091-6490
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