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Geosciences LibreTexts

5. Evolution 2

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    6559

    • Scaffolding we built on:

    1. Life as a problem solved through evolution
    2. Dependence of organisms on ecology
    3. Multiple modes of evolution
      1. Natural selection
      2. Neutral drift
      3. Gene exchange
    4. Environmental/ecological roles in evolution
    5. Evolutionary innovation

    Main Topics:

    Cooperation

    1. Symbiotic processes – mitochondria and chloroplasts
    2. Ecological systems

    Competition

    1. Eating each other – cell lysing as in game last week
    2. Resources
      1. space
      2. nutrients
      3. energy

    Feedbacks – a different way to think about interactions

    1. Evaluation of competition vs cooperation depends on “motivation”
      1. Do black and white daisies act cooperatively or competitively to stabilize temperatures in Daisyworld?
      2. Feedbacks produce ecological succession: example of fire ecology on wikipedia
    2. When positive feedbacks lead to too low a population, extinction occurs.
    3. Negative feedback lead to stability

    Summary of Main Points:

    1. Ecological-environmental interactions shape natural selection
    2. Perspective of the scientist affects models for why something happened
      1. What actually happened is independent of scientists’ models, e.g. what we think doesn’t change what happened

    Game ideas:

    1. Getting all the same suit – parts of enzymes working better together
      1. Example: the Complex III protein and how it fits with the Cytochrome C molecule

    Image of the Complex III molecule, showing the binding site for Cytochrome C near the top in yellow. (C31004 at English Wikipedia [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)])Image of the Cytochrome C molecule (Vossman [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)])

    1. Lateral gene transfer:
      1. Transformation involves uptake of short fragments of naked DNA in the environment.
      2. Transduction involves transfer of DNA from one bacterium into another via (viruses).  
      3. Conjugation involves transfer of DNA via sexual pilus and requires cell –to-cell contact.  

    Thumbnail: https://commons.wikimedia.org/wiki/File:Secondary_Succession.png