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Flashcards in Cooperation Deck (45)
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Group selection

describes natural selection operating between groups of organisms, rather than between individuals


Reproductive restraint

adaptation that has envolved because it increases likelihood of the population surviving though bad years



act to promote someone's welfare even at a risk or cost to ourselves



groups of behaviors that provide benefits to individuals other than the actor and have been selected because they do so


Kin selection ( William Hamilton)

evolutionary strategy that favours the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction

reason : investing in their children means investing in their own genotype

-> can be applied to any family relationship


Hamiltons rule (formula)

states that kin-directed behavior can be favourable by selection wherever ; c < rb ,

where c = cost
r= coefficient of relatedness
b= benefit


coefficient of relatedness

represents degree of allelic similarity


Inclusive fitness theory

an organisms genetic success is believed to be derivied from cooperation and acltruistic behavior ( altruism amongst organisms who share a given percentage of genes enables them to be passed on to following generation)


inclusive fitness

refers to an individuals direct fitness ( eg number of personal descendants) plus any additional fitness of its relatives which is consequence of its action (eg helping a relative)

direct fitness + indirect fitness



phenomena in nature where individuals under certain conditions invest in the offspring of their parents, rather than reproducing for themselves


conditions on Hamiltons rule

1 a behavior will not evolve, even if c < rb , if c is too large in absolute terms ( example: allele that results in inability to reproduce will not spread) -> thus rule is only applicable to behaviours with a weaker selective disadvantage, such as foregoing some reproduction under some circumstances

2 coefficient of relatedness alone is not sufficient to predict which behavior will evolve ( example parents at the end of their life will do more to protect their offspring than vice versa) Thus, b and c are not fixed for particular behaviors , but variable depending on the future prospects of the actor and recipient

3 coefficient of relatedness of one animal to another is always less tha the CoR of that animal to itself (which is 1)
-> ruleis compatible to behavior against own kin as wekk
-> behaviors that harm kin are particulary likely to evolve where there is local competition between relatives for finite resources


In which two situations can cooperation be considered?

1 Altruism
2 mutual benefit behavior


Mutual benefir behavior

each individual benefits from the activity of the others -> often raise issues cheating and enforcement


by-product benefit

situations where mutual benefit arises simply from every individual following its own immediate self-interest
-> benefits on another arise simply as a side effect of the benefits of the actor


direct reciprocity

idea that we help individuals who helped us in the past (tit for tat)


Which conditions must be met for direct reciprocity to occur?

- benefit of the recipient must be greater than the cost for the actor ( example food sharing : sharing could only evolve if individual B has an amount of food whereas individual A has no food and times where the reverse was true)

- need to rencounter each other multiple times

- need of mechanism for allocating cooperation differently to individuals who have been cooperative in past -> prevent cheaters who receive cooperverative benefit but never return

= c < wb ( c = cost, b = benefit, w = probability of recipient reciprocating in future)


Indirect reciprocity

idea that it might be advantagous to help individuals who we have seen helping others in the past, even if that help was not specifically directed to us

-> by helping I might get a good reputation in virtue of which others might give benefit on me
-> requires great deal of cognitive capabilities ; therefore often not common in animal species

c wher q = probability of having correct info about partners prior knowledge


Green beard effect

A green-beard effect gene (or linked genes) produces three phenotypic effects: (1) a perceptible trait — the hypothetical green beard; (2) recognition of this trait in others; and (3) preferential treatment to those recognized.


Are humans really altruistic in the lomg run?

it is not clear if contributing tocharities or joint ventures are really altruistic in the long run -> reputational and social beneftis the people might derive from doing so could easily outweigh costs over the persons lifetime



the highest level of organization of an animal society is defined by 4 characteristics :

1 overlapping generations
2 cooperative brood care
3 philopatry ( individuals remain living in their birth place)
4 reproductive altruism


Eusociality society

It is ruled by queen, the only breeding female who is larger than the res. The remainder of society composed of a few breeding male and female workers, and the young


Haploidity / Kin Selection

males come from unfertilised eggs (= parthenogenesis) thus only have one set of chromosomes but females from fertilised eggs thus they are diploid


weaknesses of Hamiltons model

1 average relatedness between sisters falls off rapidly when queen mates with multiple males

2 males share only 25 % of their sisters genes and in case of equal sex ratios , females are related to their siblings on average 0.5 whcih is not better than raising their own offspring


Ultimate Explanations

explanations about WHY a behavior exists , concerned with the fitness consequences of a trait or behavior and whether it is /or not/ selected

-> Evolutionary Function


Proximate Explanation

explanations about HOW behavior works , concerned with mechanisms that underpin trait or behavior

-> Way in which the functionality is achieved ; more interested in research


Cooperative behavior ; proximate and ultimate explanation

proximate : religion, strong reciprocity, concern for praise and blame, cultural transmision

ultimate : cooperative behavior can be mutually beneficial and can help kin -> either way , greater inclusive fitness follows


Altruism ; ultimate and proximate

u: to increase ftness of kin
p: fear of supernatural punishment, altruism is caused by feeling of shame and pride


Parochial altruism

favouring own ethnical, racial group or other insiders over outsiders


true altruism

behavior increases anothers persons reproductive success while decreasing ones own -> can only envolve through kin selection


network reciprocity

generalization of ''spatial reciprocity'' (=study how spatial structure affects evolutionary and ecologicall dynamics