Game Theory Flashcards
What is game theory
A model to analyse COMPETITIVE aspects of animal behaviour
(including habitat selection, foraging, predator–prey interactions, communication, parent–offspring interactions, and sibling interactions)
what are the 2 forms of competition
Exploitation
Interference
What is the ideal free distribution (IFD)
is a theoretical way in which a population’s individuals distribute themselves among several patches of resources within their environment, in order to minimize resource competition and maximize fitness
- IFD describes the way that animals distribute themselves among patches of resources (an optimality theory) to minimise competition; maximise fitness.
What are the two predictions that IFD suggests about animal distribution?
Distribution will:
- minimize resource competition
- maximise fitness
Where would you find 5x more sticklenacks?
Where there is 5x more food
More resources = more supply
What makes IFD ideal and free?
Ideal = animals have complete info about resource availability
Free = animals are free to go where they will do best
What kind of distribution will you find under IFD?
A stable distribution
Are individuals equal or unequal under IFD?
Equal
All have equal fitness
What are the 3 components to the IFD optimality model?
Choices
Currency
Constraints
What are the main choices in IFD
poor vs rich habitat
What is the currency of IFD optimality?
Resource intake per individual
What are the 2 main constraints of IFD optimality?
Exploitative competition
Resource availability
What is Ideal Despotic Distribution (IDD)
An optimal theory that predicts competition in territories will result in dominant individuals occupying high quality patches whilst weaker competitors are forced into less favourable ones.
It excludes some individuals from free choice.
What happens to weaker individuals when all habitats are full?
They become floaters
They will have to range habitats, waiting for an area to become available
What does despotic mean?
Tyrannical
Why is IDD despotic?
Because animals are NOT free to go where they will do best (due to dominant individuals)
Are individuals equal or unequal in IDD?
Unequal - some have higher fitness than others
is IDD stable or unstable?
Unstable
under IDD, what is a floater?
An organism that is waiting to occupy a territory since all territories are full-moves from one territory to another
What is a despot?
A ruler with absolute power
In IDD despots are the most dominant individuals
What are the 3 components of IDD?
Choices (rich or poor habitat)
Currency (Resource intake per individual)
Constraints (Interference competition; territoriality)
What is the breeding success of Great Tits in woodlands?
92%
What is the breeding success of Great Tits in hedges?
22%
What is the territory size difference in woodlands vs hedges (for Great Tits)?
Woodlands = 1.34 ha
Hedges = 3.72 ha
(Hedges have more available territory)
Why is breeding success for Great Tits far greater in Woodlands than in Hedges?
Because woodlands maximise fitness (have better resources/ conditions)
When woodlands are full, weaker individuals are excluded and forced to nest in hedges due to IDD
What occurs in woodlands to make weaker Great tits vacate to hedges?
Competitive interference (resource defence)
Name a species that lives under Ideal Despotic Distribution
Great Tits
Barrow’s Goldeneye
How do Barrow’s Goldeneye ducks demonstrate IDD?
- Male ducks defend aquatic territories aggressively
- offshore islands are less defendable & usually abandoned early
- When territories near the shore become available, they are quickly colonised because they are so prime, ducks will risk injury to secure one.
What is Strategy?
A set of behaviours/ rules on which bases the decision are made
What is Evolutionarily Stable Strategy (ESS)
= a strategy (a set of behaviours) which, if most members of a population adopt it, cannot be bettered by an alternative strategy
Who coined the term Evolutionarily Stable Strategy (ESS)?
Dawkins, 1976
Why are fights generally settled by display alone?
Because the cost of injury is too high. If injured, the individual will not be able to compete again, forage or reproduce.
Under ESS - it depends what the whole population is doing! (The majority is the best strategy)
What are the 2 conditions that need to be met for ESS to occur?
1) An individual employing strategy A must do better against another individual performing strategy A than any other strategy (All doing same strategy)
2) If a new strategy (B) evolves, for A to remain ESS then an individual employing A must do better than an individual performing B (No other strategy can better it)
Describe the ESS Hawks and Doves model
Hawk Tactic = Aggression (Fight to injure the opponent, potentially risking injury to self)
Dove Tactic = Display only (passive - will run away if opponent attacks)
Hawks can encounter other hawks, Doves can encounter other doves.
- If both adopt dove strategy, resources are shared equally.
- If both adopt hawk strategy, resources are divided evenly but with a cost of aggression.
- If dove and hawk encounter, hawk will receive all resources, dove will receive none.
What is a payoff matrix?
A visual representation of the possible/ predicted outcomes of a strategic decision
(includes data for opponents, strategies, outcomes)
In the Hawk&Dove payoff matrix, what does the V represent?
Fitness value of winning resources in fight
In the Hawk&Dove payoff matrix, what does the D represent?
Fitness costs of injury
In the Hawk&Dove payoff matrix, what does the T represent?
Fitness costs of wasted time
What is the payoff matrix equation for Hawk vs Hawk
(v-d)/2
(Fitness value - injury cost) / 2
Hawk wins 50%
Hawk injured 50%
What is the payoff matrix equation for Dove vs Dove
v/2 - T
(fitness value)/ 2 - cost of time wasted
Dove is never injured but wastes time
What is the payoff matrix outcome for Hawk in Hawk vs Dove?
V
= total fitness value
- Hawk always wins,
- Doves always flees
What is the payoff matrix outcome for Dove in Dove vs Hawk?
0
- Dove never wins but is never injured
