Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?

Sexual reproduction results from the fusion of gametes produced by male and female. Sexual reproduction causes more viable variations because:
i) There might be an error in the copying of DNA, though the event is rare.
ii)Segregation of chromosome of maternal and paternal origin at the time of gamete formation is random.
iii) There is an exchange of genetic material between homologous chromosomes during formation of gametes.
In case of asexual reproduction, variation is significantly less since only a single parent is involved. Very small changes occur due to inaccuracies during DNA copying that pass on to the progeny. Thus, offsprings of asexual reproduction are more or less genetically similar to their parents. So, it can be concluded that evolution in sexually reproducing organisms proceeds at a faster pace than in asexually reproducing organisms.