Perbandingan Teori Evolusi Darwin, Lamarck, dan Weismann | EVOLUSI - MATERI SMA KELAS XII

Introduction

This tutorial explores the comparison of three significant theories of evolution: Darwin's theory of natural selection, Lamarck's theory of inheritance of acquired characteristics, and Weismann's germ-plasm theory. Understanding these theories is essential for students studying biology, especially in high school curricula, as they form the basis of evolutionary biology.

Step 1: Understand Darwin's Theory of Natural Selection

• Overview: Proposed by Charles Darwin, this theory suggests that species evolve through a process where individuals with advantageous traits are more likely to survive and reproduce.
• Key Concepts:
  • Variation: Individuals within a species exhibit variations in traits.
  • Survival of the Fittest: Those with traits better suited to their environment are more likely to survive.
  • Reproduction: Survivors pass on advantageous traits to their offspring.
• Practical Advice: Familiarize yourself with examples of natural selection in action, such as the peppered moth or antibiotic resistance in bacteria.

Step 2: Explore Lamarck's Theory of Inheritance of Acquired Characteristics

• Overview: Jean Baptiste de Lamarck proposed that organisms can pass on traits they acquire during their lifetime to their offspring.
• Key Concepts:
  • Use and Disuse: Traits that are used become stronger, while those not used diminish.
  • Inheritance: Offspring inherit these acquired traits.
• Practical Advice: Consider how this theory contrasts with Darwin's; for instance, the idea that a giraffe's long neck evolved because its ancestors stretched to reach higher leaves.

Step 3: Examine Weismann's Germ-Plasm Theory

• Overview: August Weismann challenged Lamarck's ideas by proposing that only genetic traits passed through germ cells (sperm and egg) can be inherited.
• Key Concepts:
  • Germ-Plasm: The hereditary material that is not affected by the organism's environment.
  • Separation of Somatic and Germ Cells: Somatic changes (like muscle growth) do not affect germ cells and thus are not inherited.
• Practical Advice: Understand how Weismann's theory laid the groundwork for modern genetics and inheritance studies.

Step 4: Compare and Contrast the Theories

• Darwin vs. Lamarck:
  • Darwin focused on natural selection, while Lamarck emphasized acquired traits.
• Lamarck vs. Weismann:
  • Lamarck believed in the inheritance of acquired characteristics; Weismann refuted this by showing that only genetic changes are inherited.
• Darwin vs. Weismann:
  • Both theories support evolution, but Darwin emphasizes environmental adaptation, while Weismann focuses on genetic inheritance.

Conclusion

Understanding the differences and similarities between Darwin's, Lamarck's, and Weismann's theories provides a solid foundation for studying evolution. Familiarize yourself with key concepts and examples for each theory to enhance your comprehension. As a next step, consider examining how these theories influence current evolutionary biology and genetics.