Variation in spontaneous mutation and repair in natural population lines of Drosophila melanogaster

Abstract

SUMMARYTo measure the possible correlation between genetic damage and repair ability in natural populations of a eukaryote, we compared the spontaneous frequency of sex-linked recessive lethal mutations and male recombination, which is associated with DNA transposable element induced chromosome breakage, with DNA repair efficiency in isofemale lines of a winery population of Drosophila melanogaster from Australia. Repair efficiency was measured by maternal effects on ring-X chromosome loss. Significant amounts of genetic variability for spontaneous rates of genetic change and for repair ability were observed in the isofemale lines collected during periods of low and high population density. However, there were no correlations between repair ability and rates of genetic damage. Possible reasons for the absence of correlation are discussed, along with the observations that: (a) the frequency of lethal mutations and ring-X chromosome losses were significantly higher in the small, resident population; (b) the rates of ring chromosome losses and especially lethal mutations are uniform over periods of time; (c) and inbreeding of isofemale lines leads to a reduction of the high spontaneous mutation rates.

Copy-number dependent transpositions and excisions of the mdg-1 mobile element in inbred lines of Drosophila melanogaster

“…As soon as the lines attain a copy number of elements close to the "optimal value", they become stable. This is compatible with the classical observation that lines with high mutation rates show rate reduction over time in the laboratory (Muller, 1941;Woodruff et aL, 1984).…”

“…The transposition rate is estimated to be around io; higher values are observed only in the offspring of matings between certain strains of Drosophila melanogaster (the hybrid dysgenesis phenomenon: Engels and Preston, 1981;Thompson and Woodruff, 1981;Bingham et al, 1982;Brégliano and Kidwell, 1983;Gerasimova et al, 1984). We also have evidence against a high rate of transposition under "normal conditions" (Young and Schwartz, 1981;Pierce and Lucchesi, 1981) and against a generally high mutation rate on highly homozygous lines (Woodruff et a!., 1984;Junakovic et aL, 1984). However, highly inbred populations of Drosophila may show genome reshuffling when submitted to mass matings (Belyaeva et a!., 1982) and inbred lines of maize may have unstable mutations produced by the Mu transposable element (Strommer, 1983).…”

Highly variable recessive lethal or nearly lethal mutation rates during germ-line development of male Drosophila melanogaster

“…A similar mating scheme as described above was used successfully in earlier assays for the occurrence of mutation clusters in several laboratories (17,18,(25)(26)(27). It was estimated that lethal or nearly lethal mutations identified by the assay span over about 1,200 genes.…”

Why do species vary in their rate of molecular evolution?

“…Furthermore, efficiency of error correction can vary between individuals within a population due to differences in the genes that code for the repair machinery (e.g. Woodruff et al 1984). This suggests DNA repair efficiency is open to selection.…”