Which one of the following criteria is necessary for natural selection to occur?
AIndividuals show no variation in fitness levels.B. Individuals have the same adaptations.C. Enough resources exist for individuals to survive and thrive.D. A struggle for existence is apparent.
AIndividuals show no variation in fitness levels.B. Individuals have the same adaptations.C. Enough resources exist for individuals to survive and thrive.D. A struggle for existence is apparent.