Temperature-dependent selection in the transmission of mitochondrial DNA in Drosophila.

We previously reported a selective mode of mitochondrial DNA (mtDNA) transmission in mtDNA heteroplasmy that was induced artificially in Drosophila melanogaster; the transmission bias appeared to depend on the particular temperature at which heteroplasmic lines were maintained. Here we report investigations of the temperature-dependent mode of mtDNA transmission in heteroplasmic lines for intra- and interspecific combinations maintained separately at 22.5 degrees C, 25 degrees C and 29 degrees C for 20 generations. We have examined a selection model for mitochondrial transmission, similar to genetic selection in haploid organisms. Changes in the relative proportions of two types of mtDNA fit the expectations from the model well. The intensity of selection estimated as a selection coefficient depends on temperature. Temperature-sensitive processes thus appear to be involved in the transmission and maintenance of mitochondria.