Biology 338: Lecture 19Spring 1997

Kinship and Reciprocity

  1. Altruistic behavior: a evolutionary paradox
    1. Definitions
      1. Unselfish regard for or devotion to the welfare of others
      2. Behavior which confers a fitness benefit to recipient at some cost to self
    2. Example
    3. Possible solutions

  2. Kin selection
    1. W. D. Hamilton
      1. Hypothesis
          "The social behaviour of a species evolves so that in each distinct behaviour-evoking sitituation the individual will seem to value his neighbour's fitness against his own according to the coefficients of relationship appropriate to that situation."
      2. Coefficients of relatedness
      3. Direct fitness vs. Indirect fitness
      4. Inclusive fitness
      5. Rule
          (r x b) - c > 0
    2. Predictions
      1. Animals should help relatives rather than nonkin
        1. Belding's ground squirrels
        2. Black-tailed prairie dogs
        3. Pied kingfishers
        4. White-fronted bee-eaters
      2. Animals should help close relatives more than distant relatives
        1. Belding's ground squirrels
        2. Lions
        3. White-fronted bee-eaters

  3. Reciprocity
    1. Exchange of fitness-increasing benefits between individuals
    2. Requirements
      1. Repeated interactions between the same individuals
      2. Discrimination against "cheaters"
    3. Types
      1. Instant
      2. Delayed