Cooperation 1 Flashcards
What is cooperation?
A behavior shown that is selectively beneficial to the recipient
Why is the “selection” part important when talking about the definition of cooperation?
There are behaviors that recipients can benefit from that are not selected or intended for that purpose (this is not cooperation).
What is an example of why selection is important in cooperation? I.e. what is an example that is not cooperation?
Dung beetles: benefit from other animals defecating but that’s not intentionally done specifically for the dung beetles
What are the two kinds of cooperation? Who benefits from cooperation?
- Altruism and mutual benefit
- Recipient by definition, sometimes actor
What is an example of coop within species? What is an example of a coop between species?
Within: Volvox cells + multicellular groups (non-reproductive surround reproductive)
Between: Cassiopia jellyfish + algal symbiont (algae shares photosynthesis with jellyfish in exchange for inorganic nutrients)
What is one form of cooperation that can occur? What is an example?
- Reproduction - dominant pair of breeders (meerkats/ants)
What are two types of helpers in cooperation?
Offspring or immigrants
What question does the prisoner’s dilemma aim to answer?
Why not just be a taker without giving anything?
What is the prisoner’s dilemma? What are it’s three outcomes?
- Prisoner’s dilemma = when 2 individuals are jointly accused of committing a crime, and held separately to get them to rat on one another.
- Outcomes: Coop (both go free), 1 snitch (snitch goes free, chump gets punished hard), 2 snitch (not harsh punishment but still punish)
Which of the choices in the prisoner’s dilemma is most stable for one individual? Why?
- Most stable choice is that one individual snitches. This is because he will either go free or serve a mediocre punishment as opposed to the two options of going free and getting a harsh punishment.
Which outcome is most evolutionarily stable? Why is full cooperation not stable?
- Most stable is two snitches because they both serve a medium amount of time.
- Full cooperation is not stable because individuals are NOT AWARE of what the other cooperator would do. If one chooses to cooperate but chooses wrong, the punishment is severe compared to just snitching and still have a chance of being set free.
What is the Nash Equilibrium (hint: Prisoner’s dilemma)
Nash Equilibrium = solution where the most stable outcome is for both individuals to defect/snitch.
Under what conditions does cooperation evolve?
Common allele is more likely to be passed on to next generation as a result of cooperation.
What are two ways alleles can be passed down?
- Direct fitness - offspring
- Indirect fitness - kin
What are the four hypotheses to the evolution of cooperation?
- Kin selection - indvs. w/ same copies of same allele
- By-product benefits - cooperation as a by-product of a selfish act
- Reciprocity - Helping another individual b/c that indv. will return the help
- Enforcement - rewarding cooperation and/or punishing free loading (taking without giving)
What is the main driver of kin selection? What is one example? Why do long-tailed tits help? How can they tell who is kin, and why is it not perfect but still used?
- The main driver of kin selection is Hamilton’s Rule. It states that that rB - C > 0 if an individual will help. It’s how many offspring equivalents actor gains from cooperating.
- Examples:
a. Long-tailed tits - In the spring, birds flock in pairs and set up territories. If these fail, then the birds either start new or help others around them.
a.1. They help close kin (79% of helpers help close kin in experiment where two equidistant nests (one close kin, one not) were placed nearby).
a.2 They can tell who is kin because kin have similar “churr” calls. These calls are not genetically determined so a sibling with a different sounding call will not receive help. Still used because it’s the best option they have.
What is a second example of kin selection (not long-tailed tits)? What is different about this group compared to the long tailed tits? How is cooperation beneficial? Why do helpers still help?
- Superb fairy wrens
- In this group, helping does not lead to an increase in chick size, but a decrease in egg size.
- It’s beneficial because a decrease in egg size is less work for mom, leading to an increased survivorship for mom (increased lifetime reproduction with helpers).
- Overall, their inclusive fitness increases because they help mom, even if that increase occurs later.
What is by-product benefits? What are two examples?
Cooperation that is a by-product of a selfish act.
- Co-founded ant colonies: Two queens jointly form a colony, which makes them larger and therefore protected from raids until they get big enough to fight each other for the colony.
- Meerkats (group augmentation): Dominants breed and their offspring cannot survive w/o subs. Immigrants lose body fat while defending children.
In the meerkat example of by-product benefit, what are the three benefits to immigrating into a group? Why would adult natal males decrease help before they leave the group? Why do adult natal males not stay in the group?
- Immigrate because… increased vigilance (more time to forage), survivorship (more food, less preds), breeding opportunity (if inherit dominant position)
- They decrease help because adult helpers are looking to find helpers for themselves, so because they leave the group, they won’t find any help. Since they won’t find help, there’s no benefit to them helping in that group anymore.
- Inbreeding
