Atypical meiosis can be adaptive in outcrossed S. pombe due to wtf meiotic drivers

Killer meiotic drivers are genetic parasites that destroy sibling gametes lacking the driver allele. The fitness costs of drive can lead to selection of unlinked suppressors. This suppression could involve evolutionary tradeoffs that compromise gametogenesis and contribute to infertility. Schizosaccharomyces pombe, an organism containing numerous gamete-killing wtf drivers, offers a tractable system to test this hypothesis. Here, we demonstrate that in scenarios analogous to outcrossing, wtf drivers generate a fitness landscape in which atypical gametes, such as aneuploids and diploids, are advantageous. In this context, wtf drivers can decrease the fitness cost of mutations that disrupt meiotic fidelity and, in some circumstances, can even make such mutations beneficial. Moreover, we find that S. pombe isolates vary greatly in their ability to make haploid gametes, with some isolates generating more than 25% aneuploid or diploid gametes. This work empirically demonstrates the potential for meiotic drivers to shape the evolution of gametogenesis.