Invasion and maintenance of spore killers in populations of ascomycete fungi

Invasion and maintenance of spore killers in populations of ascomycete fungi

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I. Martinossi-Allibert, C. Veller, S. L. Ament-Velásquez, A. A. Vogan, C. Rueffler and H. Johannesson,  bioRxiv,  2020.04.06.026989. 2020.

Meiotic drivers are selfish genetic elements that have the ability to become over-represented among the products of meiosis. This transmission advantage makes it possible for them to spread in a population even when they impose fitness costs on their host organisms. Whether a meiotic driver can invade a population, and subsequently reach fixation or coexist in a stable polymorphism, depends on the one hand on the biology of the host organism, including its life-cycle, mating system, and population structure, and on the other hand on the specific fitness effects of the driving allele on the host. Here, we present a population genetics model for spore killing, a type of drive specific to fungi. We show how ploidy level, rate of selfing, and efficiency of spore killing affect the invasion probability of a driving allele and the conditions for its stable coexistence with the non-driving allele. Our model can be adapted to different fungal life-cycles, and is applied here to two well-studied genera of filamentous ascomycetes known to harbor spore killing elements, Podospora and Neurospora. We discuss our results in the light of recent empirical findings for these two systems.