An introgressed gene causes meiotic drive in .

Meiotic drive elements cause their own preferential transmission following meiosis. In fungi, this phenomenon takes the shape of spore killing, and in the filamentous ascomycete , the spore killer element is found in many natural populations. In this study, we identify the gene responsible for spore killing in by generating both long- and short-read genomic data and by using these data to perform a genome-wide association test. We name this gene Through molecular dissection, we show that a single 405-nt-long open reading frame generates a product that both acts as a poison capable of killing sibling spores and as an antidote that rescues spores that produce it. By phylogenetic analysis, we demonstrate that the gene has likely been introgressed from the closely related species , and we identify three subclades of , one where is fixed, another where is absent, and a third where both killer and sensitive strain are found. Finally, we show that spore killing can be suppressed through an RNA interference-based genome defense pathway known as meiotic silencing by unpaired DNA. is not related to other known meiotic drive genes, and similar sequences are only found within These results shed light on the diversity of genes capable of causing meiotic drive, their origin and evolution, and their interaction with the host genome.