Natural forces affecting population equilibrium

• If gene and genotype frequencies remained constant generation after generation in natural population, the population would have constant genetic composition and there would be no evolution.
• It is generally accepted that most natural populations are constantly evolving.
• Gene frequencies in Mandelian population change due to one or more of following factors:-

1. Migration
2. Mutation
3. Selection
4. Random drift

• These factors are evolutionary factors because they lead to evolution in natural population.