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Evolutionary Theory Part 2

Evolutionary Theory Part 2. Goals for today. Kin selection and reciprocal altruism How do you assess adaptive value of a behavior? Look at some behavioral examples Introduce some models to explain primate behavior. Kin selection. A form of Natural selection

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Evolutionary Theory Part 2

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  1. Evolutionary Theory Part 2

  2. Goals for today... • Kin selection and reciprocal altruism • How do you assess adaptive value of a behavior? • Look at some behavioral examples • Introduce some models to explain primate behavior

  3. Kin selection • A form of Natural selection • Individual’s fitness is influenced by fitness of relatives (they share genes!) Graph Strier pg 123

  4. Altruism-an act that benefits the helper at some cost but helps the receiver. Selfish-acting on your own self interest to improve your fitness at cost to other’s fitness Behavioral choices...

  5. How do you predict altruism? Hamilton’s Rule Degree of relatedness between actor and receiver Act’s benefit to receiver’s fitness Act’s cost to actor’s fitness c < b x r

  6. Brother’s helping rear offspring. R = .5 Benefits to helper’s fitness should be at least twice the cost. Half brothers helping rear offspring R = .25 Benefits to helper’s fitness should be at least four times the cost.

  7. Reciprocal Altruism • Behavior which is costly to actor but immediately benefits receiver (who is not related)- at some later time, receiver reciprocates. • Low dispersal rates • Social groups • Ability to discriminate between individuals • Time frame

  8. Coalitions Hamadryas baboon Rhesus monkey

  9. Chimpanzee politics Yereon- dom. male Nikkie- dom. male Luit challenges, No female support Yereon and Nikkie overthrow Luit Luit and Nikkie form Coalition, Nikkie gains Female support Luit- dom. Male Nikkie Yereon Luit, Nikkie then overthrow Yereon

  10. Criterion used to evaluate adaptation? • Evaluate costs and benefits • The compromise between these is the optimal strategy • How easily is this done in primatology?

  11. Behavioral Examples... • Infanticide

  12. Infanticide • Male tenure important factor • Female strategies • Female counterstrategies

  13. Monogamy (pairbonding) Males Costs • Mate with one female • Expend energy • defending territory Males benefits • Paternal certainty • Exclusive access to • resources

  14. Monogamy (pairbonding) Female Costs • Limited mate choice • Expend energy • defending territory Females benefits • Male care • Exclusive access to • resources

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