Variation in a population is essential for evolution and adaptation. Several mechanisms contribute to the genetic diversity observed in natural populations, but not all processes have this effect. Let’s examine the main evolutionary forces and clarify which one does not bring variation.

Mechanisms That Bring Variation

• Mutation:
  Mutation is the ultimate source of new genetic variation. It introduces new alleles into a population, creating raw material for evolution.

• Genetic Drift (Random Drift):
  Genetic drift refers to random changes in allele frequencies due to chance events. While it can reduce genetic variation by causing alleles to disappear, it also introduces variation by changing allele frequencies unpredictably, especially in small populations.

• Natural Selection:
  Natural selection increases or decreases the frequency of alleles based on their impact on fitness. It acts on existing genetic variation and can maintain or increase diversity depending on environmental pressures.

What About Random Mating?

Random mating means individuals pair by chance, not according to their genotypes or phenotypes. This process simply shuffles existing alleles and genotypes in the next generation but does not create new alleles or introduce new genetic combinations that were not already present in the population. Random mating maintains Hardy-Weinberg equilibrium and preserves the current level of genetic variation, but it does not generate new variation.

Summary Table

Correct Answer

Random mating does NOT bring variation in a population.

Correct option: (2) Random matting