Darwin's Theory of Evolution

Darwin's Theory of Evolution

Evolution by Natural Selection

  • Darwin's Journey: Evidence suggests organisms change over time.
    • Example: Observe and note an instance of this change.

Who Was Charles Darwin?

  • Charles Darwin and Evolution: A pivotal figure in the understanding of evolution.

Important Vocabulary

  • Species: A group of similar organisms capable of interbreeding and producing fertile offspring.
    • Example:
      • Species A: Toad
      • Species B: Frog
      • Toad Offspring: Cannot produce fertile, viable offspring.
      • Frog Offspring:
      • Infertile Hybrid

Important Vocabulary

  • Genetic Variation: The range of possibilities for a trait within a species.

What is Evolution?

  • Evolution: The change in a species over time.
    • The result.
    • Individuals cannot evolve; only a species can evolve.

What is Evolution?

  • Evolution is NOT a linear progression within a family tree.
    • Family Tree Example (Incorrect analogy for evolution):
      • Great Grandfather -> Grandfather -> Father -> You
    • Evolution is demonstrated through common ancestry and diversification.
    • Evolution Example (Correct analogy):
      • Common Ancestor of All Vertebrates -> Fishes, Amphibians, Mammals
      • Common Ancestor of Four-Legged Vertebrates
      • Common Ancestor of Mammals
      • Great Grandparents -> Grandparents -> Parents -> Second Cousins, Cousins, Siblings, You.

What is the Mechanism of Evolution? Natural Selection

  • Natural Selection: The process where individuals with traits that aid survival live longer and pass on those favorable traits.
    • The process.
    • Occurs due to natural variation in traits within a species.
      • Consider different alleles (versions) for traits, which creates diversity in populations.
    • Survival of the Fittest: Differences in adaptation influence fitness.
      • Variations beneficial to an organism’s survival are called adaptations.

Adaptations and Common

  • Darwin's Finches: Example of adaptation and common ancestry.
    • Different finch species on the Galapagos Islands with varied beak shapes adapted to different food sources.
    • Examples:
      • Seed-eaters: Medium ground finch, Cactus ground finch, Small ground finch, Large ground finch, Sharp-beaked ground finch
      • Cactus-flower-eaters: Large cactus ground finch
      • Bud-eater
      • Insect-eaters: Small tree finch, Medium tree finch, Large tree finch, Woodpecker finch, Vegetarian finch, Mangrove finch, Green warbler finch, Gray warbler finch
    • Common ancestor from South American mainland.

Types of Adaptations

  • Adaptations can be:
    • Structural: A physical feature (e.g., beak shape).
    • Functional: Something a structure does (e.g., venom production).
    • Behavioral: An action the organism performs (e.g., migration).

Types of Adaptations

  • Adaptations.

Evolution by Natural Selection

  • Adaptations and Survival of the Fittest.

How Do Variations Occur?

  • Organisms possess two sets of genes, one from each parent. Different forms of these genes are called alleles.
    • Examples: gene A, gene a.
  • Natural selection doesn't always favor a