Oh that, yes, but that's exactly what sex allows to happen. Imagine there are three populations of desert flowers, each with its own adaptations to drought. One

Oh that, yes, but that's exactly what sex allows to happen. Imagine there are three populations of desert flowers, each with its own adaptations to drought. One population has mutations a and b, other has c and the last one has d and e. When these populations meet, their genes recombine and in a few generations there will be individuals with all five, much more resistant than any of the parent groups. This is entirely impossible with asexual species - the strains would merely compete with each other and nothing interesting would happen.