Bio3520 Chapter 9 Cooperation
  1. Animals often exhibit cooperation among individuals despite possible        to the individuals involved.
  2. Cooperative behavior provides           to the individual only if other group members also behave cooperatively.
  3. Four models on the evolution and maintenance of cooperation are:              , byproduct            ,        selection, and      selection.
    • Reciprocity can be modeled by       theory, in particular the non-zero-sum game of             dilemma, where a strategy of "always         " may preclude cooperation.
      • Players that encounter each other again engage in the           prisoner's dilemma, where a robust strategy is      for tat (TFT), which may explain activities such as predator inspection.
        • ls T > R? This is true if a fish that trails an inspector receives a          payoff than if it inspected with an partner and the payoff is iterated when inspectors transfer the information they receive.
        • Is R > P? This is true for population that do engage in inspection behavior, since those individuals recognize the         involved in the behavior.
        • Is P > S? This is true if the payoff to mutual                 (P) is greater than that inspecting alone (S); the           behavior of many bait fish indicate that lone fish suffer high rates of predation.
        • Do inspectors use the      strategy? Inspectors appear to be:
          •       ; they cooperate in inspecting at about the same time,
          •              ; inspectors cease inspection if their partner stops.
          •            : if a "cheater" resumes inspection, its partner resumes inspection as well.
    • Byproduct mutualism involves an immediate       for not cooperating; no score-keeping is required for cooperation.
      • House sparrows may call other sparrows to share       when the benefit, such as           detection, outweighs the cost of sharing.
    • Group selection models predict that between groups, natural selection favors              if groups with more cooperators produce a benefit such as more offspring.
  4. A               analysis can reveal the evolutionary history of behaviors such as cooperative breeding.
  5. Cooperative breeding often leads to reproductive              of nondominant individuals. Often           play a proximate role in such behaviors.
  6. Cooperation among males is found in             , where two or more individuals cooperate against another individual or group, usually to gain access to females.
  7. Interspecific cooperation (            ) is also important in shaping behavior between many animal species, such as black ants and the Imperial Blue butterfly, which communicate by               their bodies.