Mod writes:
I figured that sexual species have an advantage.
Yes, many possible advantages have been suggested.
There are at least two whole books on the topic.
G.C. Williams "Sex and Evolution" and
G. Bell, "The Masterpiece of Nature".
Old Graham Bell was once my undergrad thesis supervisor at McGill U.
There are at least four or five plausible arguments put forward in these books (advantages in heterogenous or unpredicatable environments, the Red Queen model, the lottery model, etc.) to which another, more recent one can be added.
It has now been suggested that the greater cross-generational genetic diversity created by sexual reproduction would have signficantly reduced parasite loads from parents to offspring, at least initially. This is because of the high degree of physiological orchestration of parasites with their hosts. A species evolving sexuality would immediately put a lot of their parasite populations into severe difficulties, giveing them a big survival advantage over their non-sexual counterparts.