Chap.09 Cooperation

鄭先祐 (Ayo) 教授國立台南大學 環境與生態學院

生態科學與技術學系 環境生態研究所 + 生態旅遊研究所

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Cooperation

The range of cooperative behaviors Helping in the birthing process (fruit bat) Social grooming (primates)

Paths to cooperation Path 1: reciprocity Path 2: byproduct mutualism Path 3: group selection

CoalitionsPhylogeny and cooperationInterspecific mutualisms

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Cooperation

The word cooperation typically refers to an outcome from which two or more interacting individuals each receives a net benefit from their joint actions, despite the potential costs they may have to pay for undertaking such actions.

例如： jointly hunting group Two male guppies (lower left and lower center of

photo_ inspect a pike cichlid predator. Guppies cooperate during such risky endeavors. (Fig. 9.1)

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The range of cooperative behaviors

Helping in the birthing process (Rodriques fruit bat) Unrelated female “ helpers” assist

pregnant individuals in the birthing process.

During the birthing process, the helper continues providing assistance by grasping the wins of the pregnant females, thereby providing both protection and warmth, and subsequently cleaning newborn pups upon their emergence. (Fig. 9.2)

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Social grooming

Social grooming, or allogrooming (Fig. 9.3) Social grooming is “tension reduction” within

primate group. Primates are capable of exchanging one sort of

resource– for example, social grooming – for another resource in what amounts to a “biological marketplace”. Numerous experiments in primates have

examined whether individuals cooperate with one another by exchanging social grooming for aid during aggressive interactions.

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Paths to cooperation (Fig. 9.4)

Path 1: reciprocity Reciprocal altruism Prisoner’s dilemma (table 9.1)

Path 2: byproduct mutualismPath 3: group selectionPath 4: kin selection

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Prisoner’s dilemma

If both suspects cooperate, they both receive a payoff of R (reward, 1 year in jail), and if they both defect, each one receives P (punishment, 3 years in jail).

If suspect 1 defects, but suspect 2 cooperates, the former receives a payoff of T (Temptation誘惑 of cheat payoff, 0 years in jail), and the latter receives S (sucker’ 受騙者 payoff, 5 years in hail). T > R > P > S (Table 9.1) 0 > 1 > 3 > 5

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Evolutionarily stable strategies

A individual’s success may depend on what others are doing

Evolutionarily stable strategy (ESS): the optimal strategy for an individual to follow

when the rewards (payoffs) depend on what others are doing

When adopted by most members of a population, this strategy cannot be beaten by a different strategy:

no other strategy confers more fitness benefits

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The favored strategy maximizes benefit A hypothetical population of fish-catching

birds has two strategies for getting dinner Catch your own fish or steal one from another bird

Thievery is favored first: it minimizes its costs and gets full benefits from the efforts of others As the number of bandits increases, so does the

chance of encountering another robber or a bird that had its fish stolen

Then, honesty becomes the best policy When hard-working birds become common, thievery

once again becomes profitable

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The prisoner’s dilemma game

If a pair of individuals plays the prisoner’s dilemma game just once, then on the one play of the game, the only strategies possible are “cooperate” or “defect”.

In the iterated prisoner’s dilemma game, however, more complex rules, including “if-then” rules of the form “if the other individual does X, then I will do Y” can be employed – for example, “if she cooperates, I will cooperate; otherwise I will defect”.

Tit for tat (TFT) ( 一報還一報 ) = reciprocity-based strategy (Fig. 9.5)

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TFT strategy (Fig. 9.5)

1. “niceness” –never the first to defect, cooperates as long as its partner cooperates.

2. Swift “retaliation” –immediately defeats on a defecting partner since it copies its partner’s previous move and so, if its partner defects, it defects,

3. To do what their partner did no the last move.

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Predator inspection and TFT in guppies

T > R > P > S (Table 9.2)Is T > R ?Inspectors are more likely to get eaten

the closer they approach a predator (Fig. 9.6) So it is more dangerous to be leading an

inspection than lagging behind. Inspectors transfer the information that

they receive during an inspection, so that any fish lagging behind would still receive the benefits associated with inspection.

Fig. 9.7 information transfer in minnows.

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Fig. 9.7 information transfer in minnows

Some fish (transmitters) were allowed to inspect, while others (receivers) could see the transmitters, but not the predators.

As the predator approached the transmitters, the latter fed less often (A), as did the receivers (B), suggesting that receivers were getting information about danger from the transmitters.

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Predator inspection and TFT in guppies

Is R > P? If P is greater than R, it would not pay for

any individual to inspect, and the phenomenon of inspection would be rare and maladaptive when it occurred.

Fig. 9.8 inspection behavior in the wildIs P > S?

Evidence from a number of experiments indicates that single fish suffer very high rates of predation, suggesting that P>S.

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Predator inspection and TFT in guppies

Precisely measuring T, R, P, and S is difficult.

But it seems meets the prisoner’s dilemma requirement that T> R > P > S

The dynamic nature of inspection behavior in guppies and sticklebacks supports the idea that inspectors do , in fact, use the TFT strategy when inspecting potential predators.

TFT = nice + retaliatory + forgiving

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Reciprocity and food sharing in vampire bats

A typical group of vampire bats (Fig. 9.10) is composed largely of females, with a low average coefficient of relatedness (between 0.02 and 0.11).

Females in a nest of vampire bats regurgitate blood meals to other bats that have failed to obtain food in the recent past. (Fig. 9.11)

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Reciprocity and food sharing in vampire bats

When examined which individuals were involved in food sharing, it was indeed the case that, despite the fact that the average relatedness in groups was low, genetic relatives were still more likely to swap blood meals than were other individuals (Fig. 9.12)

Index of opportunity for reciprocity1. The probability of future interaction between

group members (TFT model)2. Blood meals provide a huge, potentially life-

saving benefit for recipients, while the cost of giving up some blood may not be as great to the donor.

3. Vampire bats are able to recognize one another

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Fig.9.12 vampire bat blood meals

(A) all possible association patterns that could be found between the recipient bat and others in the nest.

(B) the actual association patterns found between donors and recipients.

(C) the genetic relatedness between recipients and all other roost members

(D) the actual relatedness between a recipient and a donor.

Bats were much more likely to regurgitate a meal to close kin and to those with whom they associated more often. Bats were capable of keeping track of who fed them in the past and who didn’t.

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Neurobiological and endocrinological underpinnings of human reciprocity

Neuroeconomics: a collaborative research effort between economists and neurobiologists who specialize in brain science. Experiments in neuroeconomics typically

involve subjects who are making some economic decision.

儀器： fMRI (magnetic resonance imaging) PET (position emission tomography)

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Table 9.3 the monetary prisoner’s dilemma game, The payoff matrix for the game played by women who were either cooperating or cheating (defecting), in an economic cooperation experiment.

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(B) The fMRI scans showed that, when both subjects cooperated, brain areas associated with reward processing – OFC, rACC, the anterovetal striatum, and ACC)– were activated.

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Oxytocin (OT)

Oxytocin is a hormone that has been associated with numerous affinitive behaviors like pair bonding and parental care in nonhumans.

Because there are dense accumulations of OT receptors in the amygdala of the human brain, a region associated with social behavior. OT would also play a role in affinitive

interactions in humans. Fig. 9.14 the trust game and punishment. Fig. 9.15 Oxytocin and trust

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Fig. 9.14 the trust game and punishment

Two subjects played the trust game while one of them (player A) was hooked up to a PET scanner that monitored his brain activity.

The caudate nucleus, which is part of the dorsal striatum of the brain – depicted in yellow – was very active when player A punished player B for failing to return some of the money that A had provided to B.

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The level of oxytocin was higher when subjects believed money was sent to them voluntarily (versus sent as a function of a random draw)

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Path 2: byproduct mutualism

An individual would incur an immediate cost or penalty if it did not act cooperatively Such that the immediate net benefit of

cooperating would outweigh that of cheating.

Fig. 9.16 byproduct mutualism. Here, neither person gains by failing to

move a stone that neither can budge alone.

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Skinnerian blue jays and byproduct mutualism

The study of blue jay cooperation To use Skinner boxes

Fig. 9.17 byproduct mutualism and blue jays. Three pairs of blue jays were tested in a three-

stage experiment: Stage 1 = prisoner’s dilemma, Stage 2 = byproduct mutualism, and Stage 3= prisoner’s dilemma.

Jays cooperated when the payoff matrix matched byproduct mutualism, but not when it matched the prisoner’s dilemma.

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Skinnerian blue jays

A pair of blue jays, each of whom could peck one of two keys – a cooperate key or a defect key.

After the birds made their decisions, they were given a certain amount of food. The amount of food they obtained depended on what action they took, what action the other bird took, and which of two different payoff matrices the researchers had set up. (Table 9.4) P matrix: prisoner’s dilemma matrix M matrix: byproduct mutualism matrix

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M matrixP matrix P matrix

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House sparrow food calls

House sparrow produce a unique “chirrup” call when they come upon a food resource.

These calls appear to attract other birds to a newly discovered bounty, and as such chirrup calls may be regarded as some type of cooperation.

Chirrup call rates were higher when the food resource was divisible (Fig. 9.18) Chirrup call were associated with larger food

items– that is, those that were too big to remove from the experimental area.

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Path 3: group selection

Within-group selection Selection against cooperators and altruists. Selfish types – those who do not

cooperate– are always favored by within group selection

Between-group selection Favors cooperation

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Group selection in ants

Cooperative colony foundation has been well studied in the desert seed harvester ant Messor pergandei.

Between-group selection: adult ants are very territorial, and “brood raiding” – wherein brood captured by ants from nearby colonies are raised within the victorious nests, and colonies that lose their brood in such interactions die.

Within groups, all co-founding queens in a nest assist in excavating their living quarters, and each produce approximately the same number of offspring. (Table 9.5)

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Group selection in ants

Until workers emerge, queens within a nest do not fight, and no dominance hierarchy exists.

Fig.9.19 from cooperation to aggression Co-founding queens are cooperative during

worker production, with very little queen-queen aggression during this phase of colony development. Once workers are produced- known as “ worker eclosion”, which is when they emerge from eggs, however, queen-queen aggression in nests escalates, as does the queen death rate,

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Acromyrmex versicolor

Many nests are founded by multiple queens, no dominance hierarchy exists among queens, all queens produce workers, and brood raiding among starting nests appears to be common.

Queens forage after colony foundation. As a result of increased predation and

parasitization, foraging is a dangerous activity for a queen. Foraging involves bringing back materials that

increase the productivity of the nest’s fungus garden, which is the food source for the colony.

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A single queen taking on the dangerous role of forager for everyone in the nest. All indications are that reproduction within nests is equal between foragers and nonforagers.

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Coalitions

Dyadic interactions, two individuals interact Polyadic interaction, interactions that involve

more than two individuals. One example of polyadic interactions involving

cooperation is coalition( 聯合 ) behavior, which is typically defined as a cooperative action taken by at least two other individuals or groups against another individual or group.

When coalitions exist for long periods of time, they are often referred to as alliances ( 同盟 ).

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(A) Three male dolphins swim together, forming a long-term coalition (or alliance)

(B) Pairs of male chimps often form coalitions to act against larger, more dominant, individuals.

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Coalitions in baboons

Male reproductive coalitions in baboons (Papio anubis)

Fig.9.22 baboon coalitions. A male baboon (middle) involved in an

aggressive interaction (with male on left) will often solicit ( 請求 ) others to aid him by turning his head in the direction of a potential coalition partner (male on right).

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Alliances and “herding” behavior in cetaceans

Bottlenose dolphins “first-order” alliances in dolphins are

composed of pairs or tros of males acting in a coordinated fashion to keep females by their side, presumably for the purpose of mating.

Different first-order alliances also join together in “second-order” superalliances and aggressively attach and steal females from other alliances.

The complex social interactions inherent in dolphin superalliances, may explain the evolution of large brain size in dolphins.

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Phylogeny and cooperation

Phylogeny and cooperative breeding in birds 166 species of cooperatively breeding

passerine birds in ninety-seven genera The distribution of cooperative breeding

species in nature differed significantly from the random distributions generated by computer simulations, with some genera having more than the expected number of cooperatively breeding species, and others less than the expected number (Fig. 9.23)

Phylogeny and cooperative in social spiders

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Phylogeny and cooperative in social spiders

social spider species: 23 out of about 39,000 species

In these species, individuals build very large communal webs, jointly maintain these webs, cooperatively hunt for prey, and cooperate in raising brood born in their colonies (Fig. 9.24) With respect to foraging, this sort of

cooperation allows spiders to obtain more and larger prey.

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Phylogeny and cooperative in social spiders

Phylogenetic analysis found that sociality had evolved either 18 or 19 different times in spiders. This (18 or 19) is a remarkably high

number of evolutionary origins for cooperation.

Social spider life may be “evolutionary dead ends” (high rates of extinction) Inbreeding and skewed sex ratios

(females dramatically outnumbering males, sometimes in a 10:1 ratio)

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Interspecific mutualisms

Ants and butterflies – mutualism with communication?

In numerous species of butterflies and ants, a mutualistic relationship has developed in which butterfly pupae and larvae produce a sugary secretion that ants readily consume, and ants protect the larvae from predators such as certain species of wasps and flies. (Fig. 9.25)

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Imperial blue butterfly and ants

The benefits to both parties in this mutualism are enormous.

Butterfly larvae are much less likely to survive when ants are experimentally removed from their environment (Fig. 9.26).

Stridulating attracts ants (Fig. 9.27) Muted pupae, the experimenters applied

nail polish to its stridulatiory organs. Stridulating pupae attracted more ants

than muted pupae.

Stridulate 發尖銳的摩擦聲 ( 尤指昆蟲如蟋蟀所發 )

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Ayo NUTN website:http://myweb.nutn.edu.tw/~hycheng/

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