The mitolines (D. melanogaster) are the centrepiece for our research on mito-nuclear interactions. The lines were established in collaboration with Damian Dowling (Monash University, Melbourne). Each mitoline is a population, which means it harbours mitochondrial genotypes from one specific population of either of three continents (North America, Africa and Australia) in one of the three respective nuclear backgrounds (also naturally varying), resulting in nine different mitolines. Each mitoline was created and is maintained in three independent replicates. This allows us to investigate how phenotypes (from gene expression to fitness traits) are affected by the mitochondrial genome, the nuclear genome and the interaction between the two genomes.