What are some modern theories for why sexual reproduction was naturally

[Ferret]

selected over asexual reproduction? With regard to animals. Why did sexual reproduction evolve as the means of reproduction? Is it the diversification of genes?

[Kyle]

Yes - the diversity of individuals provides the mechanisms by which natural selection can occur to produce evolution. For example, natural selection works only because there is preexisting genetic variation. It can select one trait as more advantageous than another - therefore, without different traits (or as you said, diversification of genes), then natural selection & evolution would not be possible.

[scottsdalehigh64]

Sexual reproduction is older than animals. It exists in all life forms to some extent. The advantage of sexual reproduction is that evolution is more rapid. This makes sexually reproducing species more adaptable to changing environmental conditions.