Abstract
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 (spore)-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 spores, such as aneuploids and diploids, are advantageous. In this context, wtf drivers can decrease the fitness costs 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 spores, with some isolates generating up to 46% aneuploid or diploid spores. This work empirically demonstrates the potential for meiotic drivers to shape the evolution of gametogenesis.
Highlights
Parasites are pervasive in biology and can impose extreme fitness costs on their hosts (McLaughlin and Malik, 2017; Sorci and Garnier, 2008)
We explore the potential selective pressures meiotic drivers can impose on the evolution of gametogenesis
Most of our knowledge about S. pombe meiosis stems from studying homozygous Sp diploids
Summary
Parasites are pervasive in biology and can impose extreme fitness costs on their hosts (McLaughlin and Malik, 2017; Sorci and Garnier, 2008). Rather than being transmitted to 50% of the progeny of a heterozygote, these selfish loci use a variety of tactics to promote their own transmission into up to 100% of the gametes (Sandler and Novitski, 1957; Zimmering et al, 1970) This cheating can impose a variety of fitness costs on the host (Zanders and Unckless, 2019). Due to these costs, variants that suppress meiotic drive can be favored by selection (Burt and Trivers, 2006; Crow, 1991; Hartl, 1975).
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