Variation & Natural Selection

Introduction to Variation

Variation refers to differences between individuals of the same species. It is important for survival and evolution.

• Continuous variation: Gradual differences (e.g., height, weight).
• Discontinuous variation: Distinct categories (e.g., blood groups, eye color).

Causes of Variation

• Genetic causes: Mutations, meiosis, sexual reproduction.
• Environmental causes: Nutrition, temperature, light, disease.

Natural Selection

Natural selection is the process by which individuals with advantageous traits survive and reproduce more successfully.

Adaptation

• Structural: Physical features (e.g., thick fur, long neck).
• Behavioral: Actions or habits (e.g., migration, hibernation).
• Physiological: Internal body processes (e.g., sweating, venom production).

Speciation

Speciation is the formation of new species due to natural selection and adaptation over time. Populations become reproductively isolated and evolve independently.

Practice Questions

• Define variation and give one example of continuous and discontinuous variation. (4 marks)
• Explain two genetic and two environmental causes of variation. (4 marks)
• Describe the process of natural selection using an example. (5 marks)
• Distinguish between structural, behavioral, and physiological adaptations. (5 marks)
• Explain how speciation can occur. (4 marks)