LIFESCI 3C03 Chapter Notes - Chapter 12: Evolutionarily Stable Strategy, Nice Guy, Determinacy
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Published on 5 Apr 2017
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Ecology Selfish Gene Reading Chapter 12
Nice Guys Finish First
Nice guy (pessimistic definition): an individual that assists other members of its species at its
own expense to pass their genes onto the next generation
- This nice guy will finish last because his kind will decrease in frequency
Grudger: help each other, but refuse to help individuals who had previously refused to help
them
- Reciprocal altruism
Suckers: help others indiscriminately, making them easily exploited
Cheats: ruthlessly exploit others
Pisoes Dilea
- A idiiduals iigs deped o the ads oth the ad thei pate hae plaed
- Possible outcomes:
1. Mutual cooperation: $300 each (Reward for mutual cooperation)
2. Mutual defection: $10 each (Punishment for mutual defection)
3. A defects, B cooperates: $500 for defector (Temptation to defect), $100 fine for
cooperator (Sucker)
4. A cooperates, B defects: $500 for defector (Temptation to defect), $100 fine for
cooperator (Sucker)
- Essential features of the game: Temptation to defect is better than the Reward for
mutual cooperation, which is better than the Punishment for mutual defection, which is
better than the Sukes paoff.
- Regardless of which card the partner plays, the best move is Always Defect.
• “ukes paoff is the ost possible outcome, and can be avoided by always
defecting.
- I a sigle oud of the Pisoes Dilea, thee is o a to esue tust, theefoe
there is no reason for an individual to trust their partner.
Iteated Pisoes Dilea
- Pisoes Dilea gae epeated an indefinite number of times with the same players
- Successive rounds give players the opportunity to build up trust or mistrust, to
reciprocate or placate, forgive or avenge
- The ids eoig tiks fo the tops of oe aothes heads ae plaig a Pisoes
Dilemma game.
- Different strategies can be employed in the iterated version of the game, as opposed to
the one-shot game, in which there is only cooperate or defect.
- The iig stateg i a Iteated Pisoes Dilea gae is Tit fo Tat: ooperate on
the first move and thereafter copy the previous move of the other player
Tit for Tat versus other strategies
- Naïve Prober: Tit for Tat, but defect for a random one in every ten moves
• Tit for Tat retaliates against the defection, and Naïve Prober follows along with
the retaliation pattern
- Remorseful Prober: Naïve Prober, but avoids alternating recrimination by remorsefully
allowing the opponent one free hit without retaliating
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