Transcript ppt

The Evolution of Cooperation
The Evolution of Cooperation
I. Issue
- How can cooperation evolve, especially if by cooperating, an entity
reduces its own immediate fitness in sacrifice to that of another?
The Evolution of Cooperation
I. Issue
- How can cooperation evolve, especially if by cooperating, an entity
reduces its own immediate fitness in sacrifice to that of another?
- However, cooperation is OBSERVED and necessary:
The Evolution of Cooperation
I. Issue
- How can cooperation evolve, especially if by cooperating, an entity
reduces its own immediate fitness in sacrifice to that of another?
- However, cooperation is OBSERVED and necessary:
among genes in a genome
The Evolution of Cooperation
I. Issue
- How can cooperation evolve, especially if by cooperating, an entity
reduces its own immediate fitness in sacrifice to that of another?
- However, cooperation is OBSERVED and necessary:
among genes in a genome
among organelles in a cell
The Evolution of Cooperation
I. Issue
- How can cooperation evolve, especially if by cooperating, an entity
reduces its own immediate fitness in sacrifice to that of another?
- However, cooperation is OBSERVED and necessary:
among genes in a genome
among organelles in a cell
among cells in a multicellular organism
The Evolution of Cooperation
I. Issue
- How can cooperation evolve, especially if by cooperating, an entity
reduces its own immediate fitness in sacrifice to that of another?
- However, cooperation is OBSERVED and necessary:
among genes in a genome
among organelles in a cell
among cells in a multicellular organism
among organisms in a social group
The Evolution of Cooperation
I. Issue
- How can cooperation evolve, especially if by cooperating, an entity
reduces its own immediate fitness in sacrifice to that of another?
- However, cooperation is OBSERVED and necessary:
among genes in a genome
among organelles in a cell
among cells in a multicellular organism
among organisms in a social group
between species in symbiotic relationships
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (Hamilton, 1964)
A. Kin Selection
r > c/b
White-fronted bee-eaters
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
Nowak, M. A. 2006. Five rules for the evolution of
cooperation. Science 314:1560-1563.
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
- prisoners dilemma
B Stays Silent
B Betrays
A Stays Silent
both get 6 months A gets 10 years;
B goes free
A Betrays
B gets 10 years; A both get 2 years
goes free
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
- prisoners dilemma So, cooperation pays...but blind sacrifice does not!
B Stays Silent
B Betrays
A Stays Silent
both get 6 months A gets 10 years;
B goes free
A Betrays
B gets 10 years; A both get 2 years
goes free
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
- in the "repeated prisoner's dilemma":
B Stays Silent
B Betrays
A Stays Silent
both get 6 months A gets 10 years;
B goes free
A Betrays
B gets 10 years; A both get 2 years
goes free
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
- in the "repeated prisoner's dilemma":
- it's adaptive to cooperate if there are repeated interactions with the same partner
B Stays Silent
B Betrays
A Stays Silent
both get 6 months A gets 10 years;
B goes free
A Betrays
B gets 10 years; A both get 2 years
goes free
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
- in the "repeated prisoner's dilemma":
- it's adaptive to cooperate if there are repeated interactions with the same partner
- it works by 'tit for tat' or 'hold if it pays' (if you start on cooperate)
B Stays Silent
B Betrays
A Stays Silent
both get 6 months A gets 10 years;
B goes free
A Betrays
B gets 10 years; A both get 2 years
goes free
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
- in the "repeated prisoner's dilemma":
- it's adaptive to cooperate if there are repeated interactions with the same partner
- it works by 'tit for tat' or 'hold if it pays' (if you start on cooperate)
B Stays Silent
B Betrays
A Stays Silent
both get 6 months A gets 10 years;
B goes free
A Betrays
B gets 10 years; A both get 2 years
goes free
- cooperation can evolve only if w > c/b .... if the frequency of encounter
exceeds the cost/benefit ratio of the altruistic act. If this is the case, you may
profit in the future if the act is reciprocated (and if w is high, then there is
good chance it will be)
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
- Mutualisms: both partners have increased fitness, relative to other
members of their species, by interacting with another species.
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
- Mutualisms: both partners have increased fitness, relative to other
members of their species, by interacting with another species.
- Positive feedback can enhance the dependency between partners
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
- Mutualisms: both partners have increased fitness, relative to other
members of their species, by interacting with another species.
- Positive feedback can enhance the dependancy between partners
Atta cephalotes, the "leaf cutter"
ants, farm and eat a species of
fungus that lives nowhere else now.
Acacia and Acacia ants
Corals and zooxanthellae
Frugivory
Aphid farming by ants
Gleaners
Pollination
Protozoans in Termites
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
C. Indirect Reciprocity – “reputation”
“watcher”
Nowak, M. A. 2006. Five rules for the evolution of
cooperation. Science 314:1560-1563.
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
C. Indirect Reciprocity (Nowak 1998)
- In large populations (humans), the frequency of encounter may be low, and the
relationship is asymmetric (one person CAN help, the other may never be able to).
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
C. Indirect Reciprocity (Nowak 1998)
- In large populations (humans), the frequency of encounter may be low, and the
relationship is asymmetric (one person CAN help, the other may never be able to).
- Helping establishes a good reputation; and increases the chance that others (not
the direct beneficiaries) will help us if we need it.
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
A. Kin Selection (W. D. Hamilton)
B. Direct Reciprocity (Trivers 1971)
C. Indirect Reciprocity (Nowak 1998)
- In large populations (humans), the frequency of encounter may be low, and the
relationship is asymmetric (one person CAN help, the other may never be able to).
- Helping establishes a good reputation; and increases the chance that others (not
the direct beneficiaries) will help us if we need it.
- People who are observed to be more helpful are more likely to be helped.
- Even in other species... Bshry 2006 - Cleaner Wrasse
- wrasse eat parasites off "client" fish... but they can cheat and eat
mucous, which is bad for the client fish.
- Even in other species... Bshry 2006 - Cleaner Wrasse
- wrasse eat parasites off "client" fish... but they can cheat and eat
mucous, which is bad for the client fish.
- Client fish observe wrasses, and prefer the wrasses that don't cheat
- Even in other species... Bshry 2006 - Cleaner Wrasse
- wrasse eat parasites off "client" fish... but they can cheat and eat
mucous, which is bad for the client fish.
- Client fish observe wrasses, and prefer the wrasses that don't cheat
- AND, when WATCHED, wrasses cheat less and cooperate more...
- Even in other species... Bshry 2006 - Cleaner Wrasse
- wrasse eat parasites off "client" fish... but they can cheat and eat
mucous, which is bad for the client fish.
- Client fish observe wrasses, and prefer the wrasses that don't cheat
- AND, when WATCHED, wrasses cheat less and cooperate more...
- so wrasses cooperate with current clients to gain favor (reputation) with
others that are observing.
- cooperation can only evolve IF q > c/b, where:
q = prob. of knowing someone's reputation
C. Indirect Reciprocity – “reputation”
D. Network Reciprocity
http://www.youtube.com/watch?v=frpp6DjCaJU
Nowak, M. A. 2006. Five rules for the evolution of
cooperation. Science 314:1560-1563.
C. Indirect Reciprocity – “reputation”
D. Network Reciprocity
E. Group Selection
Nowak, M. A. 2006. Five rules for the evolution of
cooperation. Science 314:1560-1563.
E. Group Selection
Pseudomonas flourescens
Colonies with high concentration
of mat-builders (expensive
proteins) float; if cheaters
increase in number, colony sinks
and dies.
Nowak, M. A. 2006. Five rules for the evolution of
cooperation. Science 314:1560-1563.
E. Group Selection
“givers and takers” and
Evolutionarily Stable Strategies
Scenario 1:
Payoff to hawks is
always greater than
payoff to doves,
regardless of density.
Even though all doves
is better for the group,
it is not an ESS… it can
be ‘invaded’ by hawks.
All hawks IS an ESS,
though, because doves
always at disadvantage
and can’t increase in
population.
E. Group Selection
“givers and takers” and
Evolutionarily Stable Strategies
Scenario 2:
Here, the cost of competition among
hawks is high, so as hawk density
increases, payoff to hawks decline
rapidly. A population of all hawks is
not an ESS now – it can be invade by
doves. There is a stable equilibrium in
which hawks and doves are
maintained in the population.
c
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
Conclusions
- cooperation can evolve as a result of selection; even among unrelated
entities (symbioses)
- when cooperation occurs at one level, it creates a new level of
organization... cells cooperate and ORGANISMS are produced... organisms
cooperate and SOCIAL UNITS are produced.
- Cooperation allows specialization, and creates diversity at several levels
Vogel, G. 2004. Evolution of the golden rule. Science 303:1128-1131.
Game:
Give one monkey a pebble. If it gives it back (cooperation), it gets a cucumber slice.
Vogel, G. 2004. Evolution of the golden rule. Science 303:1128-1131.
GRAPE?…
what the
$%#@@!!
Game:
Give one monkey a pebble. If it gives it back (cooperation), it gets a cucumber slice.
Repeat with a second monkey, in view of the first,
but give the second monkey a grape (better
reward).
Vogel, G. 2004. Evolution of the golden rule. Science 303:1128-1131.
Game:
KEEP your
#$#@
CUCUMBER!!
Give one monkey a pebble. If it gives it back (cooperation), it gets a cucumber.
Repeat with a second monkey, in view of the first,
but give the second monkey a grape (better
reward).
First monkey will no longer return the pebble for a
cucumber.
Fair trade. Capuchin monkeys refuse to
cooperate when they see a comrade
receive a better reward for the same task.
Chimps helping strangers http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.
pbio.0050184
• 36 wild-born chimps (orphaned) – Uganda
• Two novel experimenters struggle over
stick, thrown in cage
• Experimenter reaches for stick
• Does chimp help and get the stick in 60
sec? How about a child?
Chimp
Child
Chimps helping strangers http://www.livescience.com/animals/070625_chimp_altruism.html
yes, as often as 18 month old children if the
experimenter reaches for it.
Chimps helping strangers http://www.livescience.com/animals/070625_chimp_altruism.html
Still, humans at the sanctuary provide the chimpanzees food and
shelter, so helping people out could simply be in their best interests.
Chimps helping strangers http://www.livescience.com/animals/070625_chimp_altruism.html
9 unrelated chimps ‘trained’ to use a mechanism in a pre-test.
They remove the peg, and then can walk around the corner,
through the newly opened port, and get the food.
Chimp helping chimp
• Both the target and the distracter door were held shut by chains.
• subject (S) could release the chain of the target door.
• In the experimental condition, food was placed in the target room (subject could help) by
releasing the target chain. In the control condition, food was placed in the distracter room, so
that the recipient would try to open the distracter door. In this situation, it was irrelevant (with
respect to the recipient's attempt to open the distracter door) whether the subject released
the target chain. The target measure in both conditions was whether the subject released the
target chain. (from Warneken, PLOS 2007).
• 3 acted as recipients and 6 as subjects – 10 trials for each pairing; 5 experimental and 5
controls (banana in ‘distractor’ room).
Mean percentage of trials with target behavior (releasing the target
chain) by condition. Error bars represent SEM. Each subject was
tested in both conditions in a within-subject comparison. (Warneken,
PLOS 2007).
Subjects pull bar for recipient to access food significantly more often
than the control (p < 0.025). Difference increased over trials.
The Evolution of Cooperation
Conflicts within Families
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
III. Conflicts
A. Parent vs. Offspring
Parent’s potential for
future reproduction may
favor them investing in
survival rather than
parental care.
The Evolution of Cooperation
I. Issue
II. Mechanisms (Nowak, 2006, Science).
III. Conflicts
A. Parent vs. Offspring
D. Conflicts within Families
2. Parent - offspring
Selection can favor parents that
abort care of current offspring to
improve survival and future
reproductive success…
B. Parent-Parent
IGFII gene – stimulates growth
On in males,
stimulating the
growth of their own
offspring; off in
females, as she
bears the cost of
growing embryos
and all are hers.
B. Parent-Parent
IGFII inhibitor gene –
slows growth
Off in males,
stimulating the
growth of their own
offspring; on in
females, as she
bears the cost of
growing embryos
and all are hers.
C. Sibling - sibling
B. Sibling - sibling
Conflicts....
I. Among Relatives
II. Among Non-Relatives
A. Interspecific Competition
Conflicts....
I. Among Relatives
II. Among Non-Relatives
A. Interspecific Competition
- within both populations, those
that are competing within AND between
species are at an energetic and
reproductive disadvantage.
Conflicts....
I. Among Relatives
II. Among Non-Relatives
A. Interspecific Competition
- within both populations, those
that are competing within AND between
species are at an energetic and
reproductive disadvantage.
- competititive exclusion
Conflicts....
I. Among Relatives
II. Among Non-Relatives
A. Interspecific Competition
- within both populations, those
that are competing within AND between
species are at an energetic and
reproductive disadvantage.
- competititive exclusion
- niche partitioning
Conflicts....
I. Among Relatives
II. Among Non-Relatives
A. Interspecific Competition
- within both populations, those
that are competing within AND between
species are at an energetic and
reproductive disadvantage.
- competititive exclusion
- niche partitioning
Conflicts....
I. Among Relatives
II. Among Non-Relatives
A. Interspecific Competition
- within both populations, those
that are competing within AND between
species are at an energetic and
reproductive disadvantage.
- competititive exclusion
- niche partitioning;
character displacement
Both species benefit by reducing the
interaction; once it is reduced, there
is no benefit to reestablish the
interaction.