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