Lecture on Evolution

Introduction

• Common misconceptions about evolution:
  • Evolution often misrepresented in games and media (individual characters evolving).
  • In reality, individuals don’t evolve; populations do.
• Misunderstood terminology:
  • Theory in science vs. casual conversation.
  • Fitness: in biology, it refers to reproductive success, not physical strength.
  • Evolution: does not necessarily mean complexity.

Definition of Biological Evolution

• Change in a population’s inherited traits over generations.
• Population: multiple organisms of the same species with genetic variety (trait diversity).
• Gene Pool: collection of genes within a population that can change through mechanisms.

Mechanisms of Evolution

1. Gene Flow: Movement of genes between populations, often through migration.
2. Mutations: Changes in genetic material, can be harmful, beneficial, or neutral.
3. Genetic Drift: Random events that change the genetic makeup of a population (e.g., lawn mower scenario).
4. Natural Selection: Traits that improve survival and reproduction increase in frequency (e.g., camouflage in grasshoppers).

Evidence for Evolution

Homologies

• Molecular Homologies:
  • DNA and protein similarities indicating relatedness (e.g., Eukarya domain).
• Anatomical Homologies:
  • Homologous Structures: Similar structures due to common ancestry but different functions (e.g., human arm and dog forelimb).
  • Analogous Structures: Similar functions but not due to common ancestry (e.g., bird wing and insect wing).
  • Vestigial Structures: Structures with little or no function, inherited from ancestors (e.g., claw on chicken wing).
• Developmental Homologies:
  • Similar development stages indicating common ancestry (e.g., embryonic development in Chordata).

Fossil Record

• Fossils as remains, impressions, or traces of organisms.
• Provides insight into how characteristics in populations have changed over time.
• Use of Radiometric Dating to determine fossil ages.

Biogeography

• Study of the distribution of organisms across the planet.
• Island populations and unique adaptations due to evolutionary mechanisms.
• Impact of continental drift and plate tectonics (e.g., marsupials in Australia and South America).

Conclusion

• Evolution is an ongoing process.
• Observable in organisms with short generations (e.g., antibiotic resistance in bacteria).

Final Note

• Continuous curiosity and exploration encouraged (Amoeba Sisters' reminder).