Please explain why sexual reproduction would have evolved to be the dominant form of reproduction, and how.
According to the Darwinian evolution as I understand it, life started out with just asexual reproduction (grow up, split in half, repeat).
How would it have happened that a new species evolved that used sexual reproduction, and it happened to happen twice in the same area to form the same species, one male and one female? Or were there at one time species that reproduced both sexually and asexually? If that is the case, the first species that could reproduce sexually would have had to take the genetic abnormality of being able to reproduce sexually, and though it was not used at all (as there were not partners) for likely many many generations. This unused reproductive system would have more likely bread itself out then to keep going until another genetic abnormality occured to create the opposite sex.
On top of that, sexual reproduction requires much more time/energy to do then just sitting on the couch eating some chips and splitting in half. No need to seduce that foxy lady when that foxy lady is yourself.