Lecture Notes on Evolution

Misconceptions about Evolution

• Individual Evolution Misconception: Unlike games or cartoons, individuals do not evolve during their lifespan.
• Terminology Clarifications:
  • Theory: In science, has a different meaning than in casual conversation.
  • Fitness: In biology, relates to the number of offspring and gene passage, not strength.
  • Evolution: Does not always signify increased complexity as in products.

Definition of Biological Evolution

• Biological Evolution: Change in a population’s inherited traits over generations.
• Population: Evolves, not individuals.

Mechanisms of Evolution

1. Gene Flow: Movement of genes between populations through migration.
2. Mutations: Can be harmful, beneficial, or neutral, altering genetic material.
3. Genetic Drift: Random events alter the genetic makeup of a population.
   • Example: Lawn mower impacting grasshopper gene pool.
4. Natural Selection:
   • Traits aiding survival and reproduction are passed on.
   • Example: Green grasshoppers camouflaged better, thus have higher fitness.

Evidence for Evolution

• Evolution involves changes in populations’ genetic makeup, which can lead to new species.

Homologies

1. Molecular Homologies
   • Similarity in DNA, amino acids, and proteins indicates relatedness.
2. Anatomical Homologies
   • Homologous Structures: Similar structures from common ancestry, e.g., human arm and dog forelimb.
   • Vestigial Structures: Nonfunctional structures inherited from ancestors.
3. Developmental Homology
   • Similar embryonic structures in related species.

Fossil Record

• Fossils as remains/impressions trace organism evolution.
• Radiometric dating determines fossil age.

Biogeography

• Studies organism distribution on Earth supporting evolution.
• Example: Unique island populations related to nearby ones.
• Factors: Continental drift and plate tectonics (e.g., marsupials in Australia and South America).

Ongoing Evolution

• Evolution is continuous, evident in fast-generating organisms like antibiotic-resistant bacteria.

• Closing Note: Stay curious and explore further resources on natural selection and evolution.