According to a comment at Why are not all species hermaphrodites?, asexually reproducing species go extinct more easily. However, I don't think sexual reproduction is a true evolutionary stable strategy. Since humans reproduce sexually, somebody with resistance to malaria and no sickle cell anemia can produce a kid with sickle cell anemia. For any sexually reproducing species, if a mutant asexually reproducing individual that happened to have the right genome arose, her clones would outcompete the rest of the species because almost none of them would produce an offspring with a bad trait, because they have weaker genetic drift against advantageous traits and so have a larger amount of some of them, and because they would be so slow to evolve by genetic drift to be unadapted to all those future sudden changes in the environment that they're already adapted to. Wouldn't an asexually reproducing snail from a species that snakes eat with the mirror image form from most of its species have the advantage of being harder to be eaten without having trouble finding a mate. Maybe just like humans could evolve to have resistance to malaria without the risk sickle cell anemia if they reproduce asexually, maybe if a mutant asexually reproducing cheetah with the genome that would make its clones spread arose, its clones would evolve to be furless poikilotherms that can thrive the low night temperatures because that would enable them to chase their prey longer before they became too hot to continue the chase because they would start at a lower body temperature, and individuals with that trait would never produce an offspring with any costly trait that comes with it except for a tiny costly trait.
In addition to that, if a mutant female asexually reproducing individual arose in a sexually reproducing species with the right genome and the species currently was in an evolutionary stable strategy with monogamy with each couple just able to get food fast enough to rear two children, the mutant female would also get a mate and with his help still be able to get food fast enough to rear two children both of which have entirely her genome, and then her asexually reproduced clones would spread very quickly. Once the species reaches a new evolutionary stable strategy where each individual can only get food fast enough to rear one child because there are so many females taking the available food, they may still have a slight evolutionary advantage over other species that's not nearly as high as the evolutionary advantage of asexually reproducing individuals was over sexually reproducing individuals of the same species earlier.
