TY - JOUR T1 - Experimental evidence that thermal selection shapes mitochondrial genome evolution JF - bioRxiv DO - 10.1101/133389 SP - 133389 AU - Zdeněk Lajbner AU - Reuven Pnini AU - M. Florencia Camus AU - Jonathan Miller AU - Damian K. Dowling Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/05/03/133389.abstract N2 - Mitochondria are essential organelles found within eukaryotic cells, which contain their own DNA. Mitochondrial DNA (mtDNA) is frequently used in population genetic and biogeographic studies as a maternally-inherited and evolutionary-neutral genetic marker, despite increasing evidence that polymorphisms within the mtDNA sequence are sensitive to thermal selection. Currently, however, all published evidence for this “mitochondrial climatic adaptation” hypothesis is correlational. Here, we use laboratory-based experimental evolution in the fruit fly, Drosophila melanogaster, to test whether thermal selection can shift population frequencies of two mtDNA haplotypes, whose natural frequencies exhibit clinal associations with latitude along the Australian east-coast. We present experimental evidence the haplotypes changed in frequency, across generations, when subjected to different thermal regimes. Our results thus contradict the widely-accepted paradigm that intra-specific mtDNA variants are selectively neutral; suggesting spatial distributions of mtDNA haplotypes reflect adaptation to climatic environments rather than within-population coalescence and diffusion of selectively-neutral haplotypes across populations. ER -