Invasion and maintenance of meiotic drivers in populations of ascomycete fungi

Meiotic drivers are selfish genetic elements that are able 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 genetic 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 a 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,
Neurospora and Podospora. We discuss our results in the light of recent
empirical findings for these two systems.