Killer meiotic drivers in fungi

SUMMARY Mendel’s Law of Segregation posits an equal probability for each allele to be inherited during sexual reproduction. This process, however, is subverted by killer meiotic drivers (KMDs)—selfish genetic elements that enhance their own transmission in driver+/driver− heterozygotes by selectively eliminating meiotic products lacking the driver allele. Such elements arise recurrently during evolution, and the genomic conflicts they generate are considered potent evolutionary forces shaping genome architecture and sexual reproductive systems. While documented across diverse eukaryotes—including plants, fungi, and animals—most KMDs remain molecularly uncharacterized, and their actual prevalence in nature remains elusive. In fungi, KMDs can act at two distinct life-cycle stages: by directly killing sexual spores (fungal gametes)—hence termed “spore killers”—or by targeting haploid progeny after spore germination. Fungal models have profoundly advanced our understanding of these elements. This review synthesizes current knowledge on characterized fungal KMDs (from Neurospora , Podospora , Fusarium , and Schizosaccharomyces ), emphasizing their molecular basis and interplay with the host. Approaches for KMD discovery are also discussed. Growing evidence from fungi suggests that these selfish elements are likely far more prevalent than previously appreciated.