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  • Theories of Evolution

  • Inheritance of acquired characteristics

    Proposed by Jean-Baptiste Lamarck

    Theory

    Each individual can change their own traits through use/disuse

    Evolution occurs to an individual within a lifetime

  • Inheritance of acquired characteristics

    These new traits would be passed to offspring

    Example:

    Giraffes stretch out their necks due to scarcity of food and passed that trait onto their offspring

    Not widely accepted

  • Natural Selection

    Proposed by Charles Darwin

    Theory

    The fittest organism (as determined by the environment), in a population will survive to reproduce and pass on their traits to their offspring

    Evolution occurs in a population over many generations

  • Lamarck/Darwin Comparison

  • Natural Selection

    Example 1:

    Peppered moth lighter peppered moths in England blended in with trees covered with lichen (selection against darker variation).

    More light moths, less dark moths

    Industrial Revolution Trees covered with soot, darker moths were able to blend in and more survived to pass on their traits (selection against lighter variations)

    More dark moths, less light moths

  • Natural Selection

    Example 2: Antibiotic resistance

    Certain bacterial cells are more resistant to antibiotics than others

    Over time, cells can pass the resistance to offspring resulting in bacteria that are highly resistant to antibiotics (aka superbugs)

  • Evidences for evolution

    1) Fossil evidence

    Fossil mineralized remain of an organism can be found between layers of sedimentary rocks

    Can look at the overall picture of how a species has evolved based on its environment (Horse leg bone and teeth structure)

    Older fossils are deeper (relative dating)

  • Evidences for evolution

    2) Shared Anatomical Structures

    a) Homologous

    2 organisms have SAME bone structure with DIFFERENT functions

    Shows common ancestor (or origin)

  • Shard Anatomical Structures

    Example

    Bird wing and human arm

  • Evidences for evolution

    b) Analogous

    2 organisms have similar structure and SAME function

    No common ancestor

  • Shared Anatomical Structures

    Example:

    Shark and dolphin fins

    Bird and butterfly wings

  • Evidences for evolution

    c) Vestigial

    Body part that no longer has a purpose

    Examples:

    Eyes on a blind fish

    Leg bones on a whale

    Human appendix

    Wisdom teeth

    Human tailbone (coccyx)

    Wings on flightless birds

  • Shared Anatomical Structures

  • Evidences for evolution

    3) Biochemical (molecular) similarities

    Sequence matters more similarities in DNA and amino acid sequences indicates common ancestry

    Example:

    Similarities in human, gorilla, chimpanzee hemoglobin

  • Evidences for Evolution

    4) Embryology

    Various organisms have very similar early embryological structures

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