The tragedy of the commons in evolutionary biology

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The tragedy of the commons in evolutionary biology
2014-04-08 11:44:54
tragedy commons evolutionary biology rankin 2007
conflict and cooperation
tragedy of the commons Rankin 2007 paper
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  1. Why is there an individual level temptation to cheat
    it brings economic advantages to individual, costs are distributed among all individuals
  2. What does solving the dilemma often require
    negotiation and sanctions on disobedient individuals which changes the payoffs, so group-beneficial behaviour becomes optimal for individual
  3. what was hardin's solution for tragedy of the commons
    state governance and privatization of the resource
  4. Natural selection works primarily at the level of the gene, so favours individuals that serve
    their own selfish interests
  5. a tragedy of the commons in evolutionary biology refers to a situation in which ....?
    individual competition over a resource reduces the resource itself, which can in turn reduce the fitness of the whole group
  6. what are the types of resource prone to a tragedy of the commons
    • - a pre-existing resource: an extrinsic resource over which individuals in a group or population compete
    • - Social goods
    •     a) social goods formed by cooperation ( a cooperative environment)  
    •     b) social goods formed by restraining from conflict (a non-competitive environment)
  7. in the case of cooperation being the social good, when will the tragedy of the commons arise
    if noncontributing cheaters can gain their share of the common goods provided by cooperating individuals
  8. Individuals of the bacteria myxococcus xanthus cooperate to form complex fruiting structures which release spores. cheating individuals don't invest in building non-spore parts of the fruiting structures, what happens to them?
    they produce more spores than wild-type individuals and can therefore invade and destroy the social good, causing the population to become extinct.
  9. in all cases where the social good is formed by cooperation, a well-functioning unit produces the best group fitness, but it might be advantageous for the individual to do what?
    free ride and not contribute to the social good.
  10. give an example of the second type of social good, restraining from potentially competitive acts
    territorial conflicts- resource might remain intact (area over which conflict occurs), but costs are paid by individuals who spend energy and time fighting. engaging in conflict brings costs to all group members, either through increased injury or having to invest in more conflict.
  11. how does plant competition for light illustrate the second type of social good?
    light resource remains intact. taller plants gain more access to light to compete with their neighbours and so are relatively more successful than shorter plants. height cant be achieved w/o investment in sturdy vertical biomass. selection favours plants that grow taller and shade shorter neighbours. any attempt to out grow one's neighbour is a zero sym game. assuming vertical structure contributes nothing to fecundity, we can predict taller trees, less overall productivity. such investment is wasteful at group level. tall plants less productive.
  12. How can both types of social goods tragedy be found in Bacteriocin production in bacteria
    • type 2b: production of bacteriocin kills other conspecifics as well as focal individuals, can benefit immune clonemates at expense of susceptible, unrelated bacteria that are the target. bacteriocin production creates situation in which group productivity reduced- group would do better if everyone restrained from production bacteriocins. social good is living in bacteriocin-free environment, destroyed when all individuals produce them
    • type 2a: might be advantageous for immune bacteria to cheat by refraining from producing bacteriocins themselves.
  13. what is a collapsing tragedy
    a situation in which selfish individual behaviour results in the entire resource vanishing. this type of tragedy can lead to the extinction of the whole group if the resource/ social good was essential for its survival.
  14. an example of a collapsing tragedy is work reproduction in the cape honey bee. what happens when workers cease to help the colony and invest in their own selfish reproduction
    very few individuals become workers and colony collapses.
  15. what is a component tragedy
    when the resource has been depleted but not to such an extent where it disappears completely.
  16. what is a component allee effect
    density dependent process that reduces some component of fitness at low densities
  17. how does it differ from demographic allee effects
    it doesn't necessarily diminish population growth because other fitness component might cmpnesate.
  18. component tragedies might result in a lower average fitness for the group but the group is still able to what
    persist on the resource/ benefit to some degree from the social good
  19. a tragedy of the commons wont arise if there are what to restraint
    direct benefits
  20. direct benefits of restraint behaviour are espesh likely to occur with what
    social goods
  21. when might cheating not occur in sentinel behaviour in meerkats
    if vigilant individuals have a direct personal advantage from being watchful
  22. if individuals interact locally with other highly related individuals, but compete for resources with all individuals in a population, competitive restraint will be what
  23. kin selection is likely to be important when
    in any situation in which populations are structure in some way e.g. in groups or in space
  24. population structure helps to align the interests of the individual with the interests of the group meaning what
    a reduction in group productivity resulting from individual level selfishness will come at an inclusiveness fitness cost to the focal individual- so overexploiting a common resource will be less beneficial.
  25. so groups of related individuals that show restraint in competition over common resource will be favoured over what
    groups in which individual level competition results in a tragedy of the commons
  26. What factors play a part in private ownership of the resource as well as in government control of resources
    coercion and punishment
  27. coercion has been shown to be a potential force in altering what
    the payoffs in animal societies
  28. what are present in social insect colonies that ensure that colony workers act for the benefit of the colony and don't reproduce for their own selfish interest
    policing individuals which eat worker laid eggs
  29. punishment can be subject to whatq
    social goods tragedy
  30. what is a second order free rider problem
    when punishment is costly to the punisher, there is individual level temptation not to punish cheaters
  31. What might higher order punishment lead to
    the same situation but at a higher level
  32. the benefits from overexploiting a resource aren't always linear, they diminish as what
    individuals try to compete more intensely for them
  33. diminishing returns can prevent a tragedy how?
    by reducing the overall benefit gained from increasingly investing in a selfish behaviour
  34. Diminishing returns are likely to be common when
    when individuals cannot make full use of the extra resources that they acquire
  35. give an example of diminishing returns in blood sharing vampire bats
    hungry bats need bloody more than those that have fed recently, this diminishing benefit of the state of an individual can alter the balance of reciprocal aid by diminishing the benefit gained by a cheater who wont share with other individuals even when it has fed properly
  36. selective pressures differ between what
    low and high densities of a population
  37. this creates a feedback between what
    adaptive individual behaviour and population density
  38. the strength of this feedback could have an influence on the strength of the conflict itself, preventing a what
    collapsing tragedy
  39. what is evolutionary suicide
    individual level selection prevails over higher level selection, evolution is predicted to favour selfish individuals to the extent that it can lead to extinction of higher level biological structures
  40. how can species level selection act as a conflict limiting mechanism
    species that have evolved high levels of conflict are driven extinct sooner than species in which conflicts are milder
  41. if evolutionary suicide isn't occurring, species with strong conflicts can render themselves vulnerable to what
    competitive exclusion, so competition with other species can dramatically effect species persistence.
  42. why are extant organisms expected to have robust mechanisms against the most commonly occurring cheater mutants
    any collapsing tragedies that have occurred have weeded out populations that lack such mechanisms.