W11L1 Cooperation Flashcards
Why is natural selection is based on cooperation
- genes cooperate in a genomes
-Cell cooperate in an organism
-individuals cooperate in society
The architecture of complexity is based on cooperation
Bacteria cooperate
- Individually costly behaviours that have evolved (to some extent) to benefit recipients
- Production of ʻpublic goodsʼ very common
- Provides group benefit; open to exploitation
Social insect
- Workers do not reproduce, but raise the offspring of another individual, the queen
Hamilton rule
rb > c
r = coefficient of relatedness
c = cost of cooperation
b = benefit of cooperation
What condition are required for kin selection
Novel prediction from Hamilton rules
(1) cooperative behaviour can evolve, if indirect benefits outweigh direct costs
(2) cooperative behavior is favored more, if it is directed to close kin
r= 1 for identical twins
= 1/2 for full sibs, parent-offspring
= 1/4 for half sibs, grandparent/grandchild, niece/nephew
= 1/8 for first cousins etc.
Does Hamilton’s rule explain why cooperation evolved independently so frequently in the hymenoptera?
-all Hymenoptera are haplodiploid
Females – diploid 2n (sperm fertilizes egg) produce eggs by meiosis
Males – haploid n (from unfertilized egg) produce sperm by mitosis (all identical)
-high degree of relatedness between sister 0.75 so help mother to make more sister
How does kin recognition work
- Proxies of relatedness (reared together therefore related)
- The “armpit effect” (be kind to neighbours who smell similar to you).
- Cuticular hydrocarbons of insects
Example for proxy of relatedness : naked mole rat
- Eusocial
- 70-300 per colony
- One ‘queen’ and few fathers
- All closely related
- Communal caring of pups
- Also keep each other warm
Diagram of social interaction
- both benefit: mutualism
- benefit to the receipiant but not the provider: altruism
-benefit to the actor not the receipient: selfishness
-negative to both: spite
Altruism
- Altruism (e.g. helping to raise other’s young) is costly (-) to actor, beneficial (+) to recipient
- Hallmark of cooperatively breeding animals, humans
- If natural selection favour individuals that maximize own fitness, how can altruism and cooperation evolve?
How does cooperation among unrelated
individuals evolve?
-Kin selection: helping relative
-Mutualism: win-win
- Manipulation: deception or force cooperation
-reciprocity
Action of intraspecific cooperation between non-relative
Unrelated helpers in cooperative breeders
Food sharing
Alarm calling
Coalitions
Allogrooming
interspecific mutualism
Cleaning relationships
Protection-provisioning
Insect-plant mutualisms
Method and example of manipulation
- Cooperation may be due to coercion or deception (+/+) because otherwise (-/-)
e.g. Cuckoo chick
e.g. Cooperative cichlids: ‘pay to stay in group’
e.g. Fish size hierarchies: threat of eviction
Deception in Fork-tailed Drongos
- Drongos use false alarm calls to scare others away from food
- Do this by mimicking the alarm calls of targeted species
- Targeted species reduce their response to false alarm calls when repeated, but not when varied
- Drongos flexibly vary their alarm calls (Flower et al 2014)
Reciprocal altruism (Trivers 1972)
- Actor pays small cost
- Recipient gets large benefit
- Later… Recipient repays actor
- …Both benefit
- Problem is that there is temptation to cheat
- Individuals who take advantage but don’t give back their fair share
What is game theory
- Formal way to analyse interactions between agents who behave strategically
- Mathematics of decision making in conflict situations
- Usual to assume players are “rational”
- Widely applied to the study of economics, warfare, politics, animal behaviour, sociology, business, ecology and evolutionary biology
Assumptions of Game Theory
- The game consists of an interaction between two or more players
- Each player can decide between two or more well-defined strategies
- For each set of specified choices, each player gets a given score (payoff)
Example: prisoner dilemma : rational player choose defect nut cooperation would have been better for both
Different method of reciprocity
*Direct reciprocity
*Indirect reciprocity
* Spatial reciprocity
Vampire bat example on direct reciprocity
- Wilkinson put bats from two roosts together in a lab
- He removed one bat and kept it hungry, while the rest could eat
- The hungry bat was reintroduced to the others
- In 12 of 13 cases, regurgitation of meals occurred between prior roost-mates
- Meal sharing often occurred between related individuals
- But . . . It did occur between unrelated individuals who were long term roost-mates as well
- Repeated experiment showing mutual direct benefits not explained by relatedness (Proc B 2013)
Tit-for-tat Idea of cooperation
- If you cooperate, then I will cooperate
- If you defect, then I will defect
-error destroy cooperation
-a population of tit for tat strategist cannot be invaded by a single invasion - but the vice versa also occur
Stability of Tit-for-tat
But! A cluster of TIT FOR TATs can invade ALWAYS DEFECT,* while the converse is not true.
How natural selection favor indirect reciprocity
- Strategies that base their decision to cooperate on the reputation of the recipient: ʻhelp those who have helped othersʼ
Give and you shall receive
Rule for indirect reciprocity
q > c/b
q = probability to know someoneʼs reputation
c = cost of cooperation
b = benefit of cooperation
problem with reputation
- Individuals may evolve the capacity to obscure their reputation, reducing the probability, q, that it will be known
Spatial reciprocity
- Spatial reciprocity = cooperators win against defectors by forming clusters
- In most populations some individuals interact more often
- Here reputation will be even more important, and cooperators can form cluster where they help each other
