Fundamental to the process of evolution is genetic variation on which selective forces can act in order for change to occur. consider the mechanisms listed below. all but one is a mechanism for genetic variation. that is a) gene flow. b) mutation. c) adaptation. d) sexual reproduction.

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.