Cyclic parthenogenesis helps populations cross fitness valleys

Abstract Cyclic parthenogenesis is a form of occasional sexual reproduction. Here we compare the evolvability of cyclic parthenogens and obligate sexuals in adaptive scenarios that entail the crossing of a fitness valley. With individual-based models, we find that cyclic parthenogens tend to cross fitness valleys faster, although that advantage is dramatically reduced by strong genetic correlations affecting multivariate phenotypes. We also find that, when epistasis occurs, cyclical parthenogenesis reduces the evolvability of mutational variances and covariances. In our analysis, such reductions are overwhelmed by the increase in evolvability due to the periodic storage and release of cryptic genetic diversity. Nonetheless, the relative recalcitrance against selection on mutational variances and covariances in cyclic parthenogens could be an evolutionary cost that helps explain the paradoxical rarity of cyclic parthenogenesis. Competing Interest Statement The authors have declared no competing interest.