Cooperation, Altruism, and Conflict

define altriusm

an individ. performs a behavior that reduces one’s own fitness, but provides a benefit to another individ.'s fitness

define cooperation

provides benefit for someone else and has been selected for its beneficial effect on recipient

define evolutionary stable strategy

strat or multiple strat that most members in a pop adopts and cannot be invaded by a mutant strat through natural selection

T/F - In the long term, the payoff for all individ. using diff tactics within a pop. will be the same (but not necessarily the best).

True!

Explain why altruism exist due to kin selection.

Since altruism is an individual performing a behavior that is a cost to their own fitness, but a benefit to another individual, kin selection plays a role because the altruistic behavior is more likely to occur if the individual’s relatedness to the other individual is high.

define kin selection

evo strat that favors the reprod success of an organism’s relatives at the cost of one’s own fitness (survival and reproduction)

In what 2 ways, can individuals contribute to future gen?

1) direct fitness

2) indirect fitness

define direct fitness

an individual’s reproductive success, so the surviving offspring

define indirect fitness

genetic gains by helping relatives reproduce, so the non-descendent kin that wouldn’t exist w/o the helper’s contribution

define inclusive fitness

direct + indirect fitness which is an individual’s total contribution to future gens

if 2 diploid organisms have 2 offsprings and one of the diploid organisms helps their 3 niblings rear their offspring that each have 1 offspring, what is their indirect fitness and inclusive fitness? Given that the direct fitness is 0.5 + 0.5 = 1.

direct fitness = 2 (offsprings) x 0.5 (r = relatedness) = 1.0

indirect fitness = 3 (offsprings) x 0.25 = 0.75

inclusive fitness = 1.0 + 0.75 = 1.75

define hamilton’s rule (or inclusive fitness theory) conceptually and mathematically

1) an altruistic trait is adaptive when the inclusive fitness of altruistic individuals > if those individuals had tried to reproduce individually

2) genetic relatedness btwn 2 individuals times the benefit (in reproduction) > the cost of performing that altruistic act

How do we predict altruism is common?

Hamilton’s rule: rB > C

1) individuals are closely related (r large)

a) dispersal is limited

b) rates of extra-pair copulation (means mating w an individual outside of asocial or primary pair bond) is low

2) costs to actors are low (C small)

3) benefits to recipients are high (B high)

Why does cooperation occur btwn non-relatives?

individuals gain direct benefits at some cost to themselves, but the cost is outweighed by an immediate or delayed net benefit

How can cooperation btwn non-relatives be maintained?

mutualism, enforcement, and reciprocity

define mutualism

EACH individual gains an immediate net survival or reproductive benefit from the interaction

define by-product mutualism

when a individual performs the behavior that they usually would perform, it incidentally provides a benefit to someone else

define true mutualism

when individuals only perform that behavior in the presence of other individuals, so it is costly when the interaction does not happen

Explain how cooperation exists due to mutualism.

Since cooperation is providing benefit to individuals and has been selected b/c of its benefits to the recipient, mutualism ensures that the interaction serves an immediate benefit for each individ.

Explain how cooperation exists due to enforcement.

enforcement ensures that there is greater cost in failing to performing the behavior than the cost of performing the behavior

Explain why cooperation exist due to reciprocity.

Cooperation exists b/c reciprocity require repeated role exchanges, recognizing cheaters, and the benefit outweighs the cost of the cooperative act