Cyclic Parthenogenesis Can Help Adaptive Evolution in Rugged Fitness Landscapes

Abstract

Cyclic parthenogenesis is a form of occasional sexual reproduction and recombination. The temporal variation in recombination it causes leaves population genetic signatures, but in smooth fitness landscapes has no effect on the rate of phenotypic evolution. In this thesis, I compare phenotypic evolution of cyclic parthenogens and obligate sexuals on rugged fitness landscapes, that is, in adaptive scenarios that entail the crossing of a fitness valley. I consider scenarios involving panmixias and spatially structured meta-populations. With individual-based models, I find that cyclic parthenogens tend to cross regions of low fitness more slowly, but once crossed, they establish more rapidly. Overall, in panmictic populations, cyclic parthenogens cross fitness valleys faster. In meta-populations, cyclic parthenogens tend to adapt to new habitats faster when population structure is weak and migration rates are low. On the other hand, when meta-populations are highly structured and migration rates are high, obligate sexuality can be advantageous. The present work adds to the growing body of theoretical and observational studies that have supported either the evolutionary equivalency or advantage of cyclic parthenogens over obligate sexuals.