Darwin's Theory of Evolution Lecture Notes

Introduction to Darwin's Theory

• Origin: Proposed by Charles Darwin in "On the Origin of Species" (1859).
• Basic Principle: Evolution by natural selection—organisms evolve through inherited traits.

Key Concepts

Variation in Traits

• Variation within a population (e.g., beak shape in Galapagos finches).
• Traits affecting adaptability impact survival and reproduction.

Natural Selection

• Definition: Process where organisms better adapted to their environment tend to survive and produce more offspring.
• Survival of the Fittest: Refers to organisms' reproductive success, not physical strength.

Microevolution vs. Macroevolution

• Microevolution: Small changes in species over short periods (e.g., color, size).
• Macroevolution: Large-scale changes leading to new species (e.g., dinosaurs to birds).

Sexual Selection

• A subset of natural selection focused on attracting mates (e.g., peacock plumage).

Example: Whale Evolution

• Whales evolved from land mammals through natural selection.
• Changes like nostril positioning evolved into blowholes.
• Fossil evidence supports transitional forms (e.g., Ambulocetus).

Historical Context

Other Theories

• Alfred Russel Wallace: Independently conceived similar evolution theory.
• Lamarckian Evolution: Proposed traits acquired through behavior could be inherited (later disproven).

Modern Evolutionary Synthesis

• Integration of genetics with Darwin's theory.
• Genes & Mutations: Mutations in DNA create variation; beneficial ones persist through natural selection.

Evidence Supporting Evolution

Genetics

• DNA similarities across species support common ancestry.

Fossil Record

• Shows progression from ancient to modern species.

Developmental Biology

• Embryological similarities indicate evolutionary relationships.

Controversies and Acceptance

• Some opposition due to religious beliefs; debates on teaching evolution.
• Scientific consensus: evolution is fundamental biology, akin to quantum mechanics in physics.

Additional Resources

• NOAA presentation on whale evolution.
• Darwin's original book "On the Origin of Species".
• Articles on natural selection and the distinction between theories and facts.