B unit 1

  • Evolution Definition:

    • Change in appearance or behavior of organisms over time.

    • Change in allele frequency in a population over time.

  • Key Figures Related to Evolution:

    1. James Hutton:

    • Scottish geologist.

    • Proposed gradual changes in rocks and landscape.

    1. Charles Lyell:

    • Friend of Darwin.

    • Suggested Earth is old and changes occur gradually.

    1. Jean-Baptiste Lamarck:

    • Proposed inheritance of acquired characteristics.

    • Example: Giraffe's long neck developed by stretching to reach leaves is incorrect.

  • Darwin, Wallace, and Natural Selection:

    • Both were naturalists and traveled extensively.

    • Darwin's observation of finches in the Galapagos led to the idea of natural selection.

    • Key Observations:

    1. Traits are inherited.

    2. More offspring are born than can survive (competition).

    3. Offspring differ in traits.

    • Natural selection: Advantageous traits are passed down due to better survival.

  • Natural Selection Example:

    • Work of Rosemary and Peter Grant on Galapagos finches.

    • Drought in 1977 favored birds with larger beaks for food.

  • Natural Selection Overview:

    • Environmental factors influence survival and reproduction.

    • Advantageous alleles spread through populations.

  • Sexual Selection:

    • A type of natural selection influenced by mate choice.

    • Types:

    • Male-Male Competition: Males compete for female access.

    • Female Choice: Females prefer males with attractive traits (e.g., bright feathers).

  • Benefit of sexual selection: Healthy males pass on good alleles.