Competition I Flashcards
When does competition occur? What makes a resource limited? What are three examples of a limited resource?
- When animals exploit the same limited resource
- The utilization of the resource limits fitness
- Food, mates, space
What determines if there is a frequency dependent behavior pattern for a resource?
If two or more individuals exploit the same resource, then the payoff of a behavior will depend on the frequency of other behaviors from other individuals.
What is the optimization criterion for competition? What does it mean?
- stability
- Means that we’re neither max. or min. a currency, but finding the most stable outcome for all parties involved
What does ESS stand for? What does it mean? What is a human example? Does an ESS maximize fitness?
- evolutionary stable state
- A strategy that, if all members adopt, cannot be invaded by an alternative strategy
- Going to a concert - ESS is standing because no matter if someone else stands or sits, you can still see (even though standing using more energy). Then the person that you’re blocking needs to stand, so standing is best.
- No, it is what is stable for the population, not to maximize fitness (which would be sitting at the concert for example)
What does Hawk/Dove game demonstrate? Describe it. What is a Hawk? What is a Dove?
- Maynard Smith’s way to describing how an ESS may not maximize fitness
- Two individuals are about to fight over same resource and they can either be Hawk or Dove.
- Hawk - always fights (may injure opponent or risk injury), Dove - never fights
What are the variables needed to understand the Hawk/Dove game? What are the four outcomes and what are the payoffs of each outcome given if individuals are either Hawk or Dove?
- V = value of resource, C = cost of losing
- Outcomes and Payoffs
1) Attacker = Hawk
Opponent = Hawk = 1/2V -
1/2C = -25
Opponent = Dove = V = +
50
2) Attacker Dove
Opponent = Hawk = 0
Opponent = Dove = 1/2V = +25
What is the ESS of the Hawk/Dove game? Why?
- Mix of hawks/doves
- If the opponent is a Hawk, then it is better for you to be a dove. If the opponent is a Dove, it is better for you to be a Hawk.
What do we know about the ESS of the hawk/dove solution and its fitness? What is the math associated with the Hawk/Dove ESS?
The fitness of being both a hawk and dove must be equal.
Please refer to notes to answer 2, I don’t want to type in all the math.
If we have a graph with the x axis (and payoff to hawk or dove on the y-axis) being the proportion of Hawks in the population, where does the ESS lie, and what does either side of the ESS represent?
- ESS is where proportion of H = 0.5.
- To the right of this is would be doves invade, to the left is that hawks would invade.
What happens if you decrease the danger of being a hawk? What is the caveat to this?
- Then Hawks will invade a population of doves
- The caveat is that if everyone is a Hawk, then their payoff is lower overall than if everyone was a dove.
What are two ways animals compete for limited resources? Which of these is the ideal free distribution an example of?
- directly (aggressive actions)
- indirectly (influence on jointly limited resources)
- Indirect
Describe the ideal free distribution. What is an important assumption about the ideal free distribution? What are three other important assumptions?
- 2 habitats (rich with lots of resources and poor with few resources)
- Resources renew at a fixed rate (so food density is dependent solely on the number of individuals there)
- No fighting, can move freely to either habitat, everyone knows the density of food at each spot
What are the two results of the ideal free distribution?
Animals –> rich habitat until food density drops below the poor habitat density
After this happens, they should distribute so everyone does equally well.
What are three examples concerning the ideal free distribution? Is the IFD followed in these examples?
- Sticklebacks - dripped Daphnia at two different rates into the tank, and found that they did distribute themselves by the ideal free distribution, starting at the faster one, then redistributing once outcomes were equal. YES
- Mallards - 33 mallards two different rates, found 22 went to the fast one, 11 the other and when the drips were switched, the same happened. YES
- Dung flies - females prefer fresh dung and so less females at old cow pies. So old = poor/bad. So, over time (as cow pie goes bad) the number of males decrease, but the rate of mating stays the same (IFD).
