Separating the sexes : sexual conflict and how to resolve it

Abstract: During the evolution of sex, different sexual conflicts arise. Sexual conflicts reduce fitness of the opposite sex. That is why several mechanisms have evolved to resolve them, which leads to rapid and unpredictable co-evolution of male and female traits involved in reproduction. This rapid co-evolution of male and female reproductive traits driven by sexual conflict can further lead to reproductive isolation resulting in speciation.             I used the hermaphroditic fungus Neurospora crassa, which has two mating types, as a model organism. Mating types are proxy to sex, because both are needed for sexual reproduction, but they are not limited to either sex role. However by using male pheromone knock-out lines, I created an evolutionary setup, where either mating type is forced to adapt to its restricted sex role. After 21 sexual generations of adaptive co-evolution, I tested if mating types had adapted to the assigned sex by measuring fitness (production of sexual spores called ascospores). I used three evolutionary setups (lines): Δccg4 lines, where mat A is female and mat a is adapted to the male role, Δmfa1 lines, where conversely mat A is adapted to the male role and mat a is female, and wild-type lines used as controls, where both mating types have maintained and adapted to both sex roles. And discovered one Δccg4 line, which indeed adapted to the newly assigned sex roles. At generation 15 and 21 I obtained mixed results for the presence of sexual conflict by correlating male and female fitness in hermaphroditic partner mat a in this line, however I found a sexual conflict also in the asexual growth, where male role is associated with increased, but female role with decreased mycelium growth rate. This work will further allow to study genomic mechanisms underlying this adaptation.