8. Why should a female produce male offspring if she could produce an identical copy of herself by clonal reproduction? How do sexual populations avoid Muller's ratchet?

The mutational load in an asexual lineage cannot decrease below that in the least-loaded clones, but the load can increase in all clones as they acquire new mutations. Muller's ratchet clicks with each new mutation, and with each click of the ratchet the overall

fitness of the population declines ever so slightly, eventually that lineage will accumulate mutations or be wiped out bysome unforeseen disaster.

Sex has evolved recombination as a way to create diversity that allows exsiting variation to be generated by scrambling the material between male and female parents, thereby avoiding Muller's ratchet.