Biology 338: Lecture 1Spring 1997

Natural selection/Levels of analysis

  1. Charles Darwin
    1. Review
    2. Reasoning
      1. Reproductive potential
      2. Variation
      3. Heredity
      4. Differential reproduction
    3. Evolution vs. natural selection
    4. Implications

  2. "Units" of selection
    1. Question
    2. Data
      1. Avian clutch size
      2. Feeding hungry young
      3. Infanticide in lions
    3. Conclusions

  3. Levels of analysis
    1. Proximate causation ("How?" questions)
      1. Mechanisms (How does it work?)
      2. Ontogenetic processes (How does it develop during a lifetime?)
    2. Ultimate causation ("Why?" questions)
      1. Fitness consequences (Why is it favored by natural selection?)
      2. Evolutionary origins (What were its evolutionary precursors?)

  4. Case study: Belding's ground squirrels
    1. Natural history
    2. Question: What causes juvenile male Belding's ground squirrels to disperse?
      1. Mechanistic (physiological)
      2. Mechanistic (cognitive)
      3. Ontogenetic
      4. Fitness consequences
      5. Evolutionary origins

  5. Hypothesis testing
    1. Weak test of a hypothesis
      1. Make predictions
      2. Test predictions (collect data)
      3. Analyze data
      4. Interpret results
    2. Strong test of a hypothesis
      1. Generate alternative hypotheses at the same level of analysis
      2. Identifying a critical prediction for each hypothesis
      3. Test predictions (collect data)
      4. Analyze data
      5. Interpret results
    3. Example: Infanticide in lions - revisited


There was a man who walked on water; he came to set the people free.
He was the ultimate example, of what love can truly be
'Cause his love was his life...
And he gave it away!
MWS, "Give It Away"