Cooperation Flashcards
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
altruism
act to promote someone’s welfare even at a risk or cost to ourselves
cooperation
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
alloparenting
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
Eusociality
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
