ANSWERS to QUIZ 6 -- Sean's Wed 8 am SECTION

1. Categorize Tinbergen's four questions about animal behavior as proximate or ulitmate questions and explain why (20pts)?

 

  1. Causation refers to the proximate causes of behavior such as the hormones, genes, nerve impulses that control the expression of behaviors.
  2. Development refers to the ontogeny of behaviors such as imprinting, or in the case of cognition, issues of learning, which are all proximate mechanisms.
  3. Evolution refers to the phylogenetic context in which the behaviors are found. For example, the prevalence of parental care in birds, but not reptiles (with some exceptions) is an example of the taxonomic affiliations of some behaviors. This has to do with ultimate causes, for example, in the case of "phylogenetic constraints".
  4. Function refers to the adaptive value or contribution that the behavior makes to fitness.

Some set of sentences that says a few of the following points: Causation in Tinbergen's view is concerned with Proximate Causation or mechanism. Development is also considered to be in the category of proximate cause. However, evolution or phylogenetic context is squarely in the field of ultimate cause, as is the issue of function as such issues of adaptive value or fitness are directly related to evolution and evolutionary change. Our study of animal behavior begins with a consideration of the ultimate causes of evolutionary change -- adaptation and natural selection.

2. Explain why "cheaters" inhibit the evolution of altruistic behavior and group selection (20pts).

The simple problem with group selection is that it can always be invaded by an individual "cheater" strategy. For example, using the case of the evolution of self-limiting behavior (a la Wynne-Edwards): an individual that does not live by the "group rules" and does not limit their own behavior will gain resources relative to other members of the group. These cheaters get higher fecundity, and thus spread by virtue of enhanced fitness within the group.

We could could the argument in terms of an ESS (other verbal explanations that get the gist of ESS will likewise work). True altruism not an evolutionary stable strategy (ESS) because it can be invaded by a selfish morph. What is an evolutionary stable strategy or ESS? An ESS is a strategy that is so good that it is uninvadable by any (and all) mutant strategies that arise in the population. Because altruism can be invaded by cheaters, altruism is not stable over the long haul.