Cycle 10 Flashcards
Fitness benefit to recipient + Fitness benefit to actor (_______)
Cooperation
Fitness cost to recipient + Fitness benefit to actor (_______)
Selfishness
Fitness benefit to recipient + Fitness cost to actor (_____)
Spite
Individuals often appear to sacrifice their _____ for the good of others
fitness
Fitness cost to the recipient + Fitness cost to actor (______)
Altruism
Which type is most common and hard to reconcile with NS?
Altruism
Passing up opportunities to reproduce
Birds that help parents take care of children
Bees: whole groups of individuals that shut down ovaries and help the queen produce more sisters
EXAMPLE OF:
Ex: Reproductive altruism
One way individuals sacrifice their fitness:
Ex: Risking your own life for others
Is it “altruistic” to provide costly care to your descendants
NO: Parental care is not a problem for traditional NS theory
Providing care to your direct descents can be reconciled with how we think selection works
It isn’t exactly altruistic in the sense that you’re reducing your fitness because you sacrifice yourself so your offspring can survive (they are carrying your alleles, and your genes can survive/be passed onto the next generation)
____ selection: individuals act selflessly “for the good of the group”
Group
What is group selection and why is it not enough evidence?
Claimed that groups that are made up of good citizens will do better than groups composed of selfish individuals
We know now group selection is probably NOT a strong enough force to explain altruistic behaviors because even though yes, groups that are composed of mostly helpful individuals do better, it only takes one bad person to sneak in and be successful by others but not help
Free-rider problem
_______ theory:
Expands our view of fitness
Kin selection
_____ fitness
One way of getting your alleles into the next generation is by producing multiple offspring
Direct
_____ fitness
Also getting alleles by helping non-descent relatives survive and reproduce
Your relatives also have a lot of the same alleles that you do
indirect
If benefit to the actor’s indirect fitness outweighs the cost of the actor’s direct fitness, helping is favored by ______
kin selection
______ Rule: helpful behaviors favored if rb>c
Hamilton’s
_____ fitness
Direct fitness + indirect fitness
Inclusive
_____ (b) to actors relatives
Benefit
…does this outweigh the ___ (c) to actors’ direct fitness?
cost
Weighed by the degree of ______, r
relatedness
Five of your first cousins (r=0.125) and two of your half-siblings (r=0.25) are about to die. You have the opportunity to save them all, at the cost of your own life. According to kin selection, should you sacrifice yourself?
YES
(5x0.125) + (2x0.25) = 1.125 lives
1.125>1
A bird has the opportunity to help its parents raise four additional full siblings that would not have survived without its help OR to find a mate of its own and produce three offspring. What should the bird do?
(4x0.5) = 2
OR (3x0.5) = 1.5
Help raise siblings
Another bird, different options: Bird can help its mother and stepfather raise four additional half siblings that would not have survived without its help, OR to find a mate of its own and produce three offspring. What should the bird do?
(4x0.25) = 1
(3x0.5) = 1.5
Find a mate and produce its own offspring
_______: individuals have overlapping but not identical genetic interests with relatives
Genetic conflict
______ in relatedness cause disagreement over when helpful behavior is appropriate
Asymmetries
Hamilton’s Rule: helpful behaviors increase the helper’s _____ fitness if rb>c
inclusive
_ = cost to the helper
c
Could be re-writen as “helpful behaviors increase any individual’s inclusive fitness if ______”
r1b>r2c
__ = focal individual’s relatedness to the recipient
r1
To your parents, you and your brother are both equally important – parents hope that you help your brother if…
(0.5)(10)/0.5 = 10
b>10
Helping your brother (r=0.5) will cost you 10 units of fitness (c=10). What benefit (b) to your brother makes this worthwhile?
r1b > r2c
Rearrange to b > r2c/r1
To you, your brother is half as important as yourself – help your brother only if…
(1)(10)/1 = 20
b>5
What about your father’s point of view?
No nonzero cost is acceptable
__ = focal individual’s relatedness to the helper
r2
__ = benefit to the recipient
b
If b<5, or if b>20, there’s no ____
conflict
To your brother, he is twice as important as you – brother hopes you will help if…
(0.5)(10)/1 = 5
b>5
Many apparently altruistic behaviors can be explained by kin selection; others by ____ altruism (opportunities for future payback)
reciprocal
What about your stepfather’s point of view?
Always help, even if c>20 units
If you help your half-sister (same mother, different dads), her direct fitness will increase by 20 units(b=20).
From your mother’s point of view, when should you help? (What maximum cost to you?)
____
c<20
Even when genetic interests overlap (between close relatives) they can be different enough to induce ___
conflict
If you help your half-sister (same mother, different dads, r=0.25), her direct fitness will increase by 20 units (b=20). How much of a cost to your own direct fitness are you willing to incur to provide this help?
From your point of view
r1 =0.25 , r2 =1
helping your half-sib increases your
inclusive fitness if …
* help if and only if …
is r1b > r2c?
r1 = individual’s relatedness to the recipient of help
r2 = individual’s relatedness to the helper
b = benefit to the recipient of help
c = cost to the helper
r1b>r2c rearrange - r1b/r2>c
0.25(20)/1>c
5>c
Focuses on _____ behavior
instinctive
Many social behaviors that seem ‘altruistic’ can be explained by shared genetic interests - _____ not altruism
cooperation
Hamilton’s rule and kin selection theory does ___ require animals to do math
not
How can we explain helping behavior between unrelated individuals?
GAME THEORY
Two players playing a game and faced with two behaviors (good vs bad)
Payoff matrix (and each outcome depends on what the individual chooses to do, and also what partner does)
Prisoners dilemma
Don’t need to know what your partner is going to do to make the most rational choice
Regardless of what your partner does, the rational thing is for you to:
no cooperate /cheat
Prisoner’s dilemma outcomes:
1)______ (you cheat, partner cooperates)
Temptation
2) _____ (you cooperate, partner cooperates)
Reward
3) _____ (you cheat, partner cheats)
Punishment
4) _____ (you cooperate, partner cheats)
Suckers payoff
One solution to the dilemma:
repeated interactions between individuals
Repeated interaction between individuals can favor _____
cooperation
Individuals can recognize, remember, and reward helpful partners
Individuals can recognize, remember, and punish (or avoid) no-helpful
EX:
Primates (humans and monkeys)
Selection can favor helping non-relatives if
they help you later
‘______ altruism’ is a form of cooperation, not true altruism
Reciprocal
____ and ___ social groups (increases likely hood of meeting them again)
Small and stable
Human social emotions (trust, gratitude, resentment, guilt) may have evolved as adaptations for
social score-keeping
True altruism is very ____ (selected against), but cooperation is widespread
rare
