MT 1 Info

Evolution

  • Descent with Modification

  • Genetic changes in populations of organisms over time.
    - Gene frequency changes from one generation to another.
    natural selection, genetic drift
    - Populations evolve. Individuals do not evolve.

  • Evolutionary Applications

    • Disease origin and transmission

    • Identifying functionally important noncoding DNA (higher peak=greater sequence conservation)

    • Identifying molecules with history of functional divergence

    • understanding resistance evolution

    • Understanding tumor and metastasis evolution

  • Darwinian medicine
    Pharmacogenomics, personalized medicine
    Origin and maintenance of disease-causing alleles
    - Sickle-cell
    - Cystic fibrosis
    - Hypertension, diabetes, obesity
    Clinical/public policy practices to reduce evolutionary
    pressures favoring virulence, drug resistance (e.g. tuberculosis)

  • Common misconceptions about evolution
    1) It is just a theory
    2) Evolution = natural selection, or Evolution is random
    3) Evolution results in organisms perfectly adapted to their environment
    4) Evolution happens for the good of the species
    5) Some life forms are higher on the ladder of life than are others
    6) Evolution is a linear march of progress from simple to complex

  • A (very) brief history of evolutionary biology
    Rise of the physical sciences in 16th and 17th century
    1) The world is orderly and can be described by “laws” rather than
    divine intervention
    2) Natural laws reveal God’s wisdom
    3) What works for the physical science should also work for biology

  • The search for laws or principles responsible for biology

    • An early organization of biological variation

      Scala naturae (from Bonnet 1764)—Creation of species
      Gradation of complexity
      Problems
      -       “Linear” model cannot accommodate all taxa
      -       Fossils/extinction
      -       Vestigial organs

    • Species arise by natural causes, not creation
      Jean Baptiste Lamarck (1744-1829)
      Sought natural explanations for graded complexity and biological diversity
      Sought explanation for extinction
      “May it not be possible that the fossils in question belonged to species still existing but which have changed since that time and been converted into the similar species that we now actually find.” Lamarck 1809

    • Lamarck’s Hypothesis

      • Spontaneous generation

      • Inevitable progress towards greater complexity (innate property of life)

      • Inheritance of acquired characteristics

  • Geology

    • Charles Lyell (1797-1895)
      -       Uniformitarianism
      -       Gradual change
      -       Vast time periods
      -       Same processes in the past as in the present
      -       Viable alternative to catastrophism

  • Problems with special creation
    -     Cuvier - fossil forms tend to become more distinct with age
    -     Geographic variation - species not fixed
    -     Hybrids - species not discrete
    - Vestigial organs

  • Alfred Russell Wallace (1823-1913)
    -     Naturalist - S. America and Malaysia
    -     Independently conceived of evolution by Natural Selection
    -     Sent Darwin a manuscript asking him to communicate it to Lyell for publication
    -     Lyell arranged for joint publication, July 1, 1858 - the paper attracted no attention
    -     Darwin’s “abstract”, On the Origin of Species, November 24, 1859—controversal socially and scientifically

  • Origin of Species