Sex drives intra-cellular conflict in yeast

Theory predicts that sex can drive the evolution of conflict within the cell. During asexual reproduction genetic material within the cell is inherited as a single unit, selecting for cooperation both within the genome as well as between the extra-genomic elements within the cell (e.g. plasmids and endosymbionts). Under sexual reproduction this unity is broken down as parental genomes are distributed between meiotic progeny. Genetic elements able to transmit to more than 50% of meiotic progeny have a transmission advantage over the rest of the genome and are able to spread, even where they reduce the fitness of the individual as a whole. Sexual reproduction is therefore expected to drive the evolution of selfish genetic elements (SGEs). Here we directly test this hypothesis by studying the evolution of two independent SGEs, the 2µm plasmid and selfish mitochondria, in populations of Saccharomyces cerevisiae. Following 22 rounds of sexual reproduction 2µm copy number increased by ~13.2 (...