Answer
See work below.
Work Step by Step
Genetic variation within a population is a prerequisite for evolution because if all of the individuals within a species had a very similar genome, then there would be very little change in that population, preventing the development of new species. Genetic variation allows for many different, unique traits to develop in different individuals within the species. Through the process of natural selection, the traits that best allow individuals to reproduce and pass down their genome will become more accentuated and prevalent throughout generations. Eventually, as the species is faced with a broader array of new challenges and habitats to adapt to, this process will allow an entirely new species to diverge from the rest as a result of its unique and advantageous trait. The greater the genetic variation of a species to begin with, the more such advantageous traits will develop, and the greater the number of new species will evolve.