Sexual reproduction involves two parents, whereas asexual reproduction involves only one parent. So, the offspring resulting from sexual reproduction will have mixed characteristics from both the parents and therefore, will be different from each parent. This will bring variations in the population. Variations are important for the survival of species over time. If a population of asexually reproducing organisms is suited to a particular environmental condition and the condition is drastically altered then the population would be wiped out. However, if some variations were to be present in a few individuals in this population, there would be some chance for them to survive in the new environmental condition.