Cooperation (evolution)

The diversity of taxa that exhibits cooperation is quite large, ranging from zebra herds to pied babblers to African elephants.

Spending time and resources assisting a related individual may at first seem destructive to an organism's chances of survival but is actually beneficial over the long-term.

Hence, cooperation seemed to pose a challenging problem to the theory of natural selection, which rests on the assumption that individuals compete to survive and maximize their reproductive successes.

For example, when a ground squirrel sounds an alarm call to warn other group members of a nearby coyote, it draws attention to itself and increases its own odds of being eaten.

[4][nb 1] Different theories explaining kin selection have been proposed, including the "pay-to-stay" and "territory inheritance" hypotheses.

The "pay-to-stay" theory suggests that individuals help others rear offspring in order to return the favor of the breeders allowing them to live on their land.

The "territory inheritance" theory contends that individuals help in order to have improved access to breeding areas once the breeders depart.

[9] Studies conducted on red wolves support previous researchers' contention that helpers obtain both immediate and long-term gains from cooperative breeding.

[4] Researchers evaluated the consequences of red wolves' decisions to stay with their packs for extended periods of time after birth.

[11] In their meta-analysis, researchers compiled data on kin selection as mediated by genetic relatedness in 18 species, including the western bluebird, pied kingfisher, Australian magpie, and dwarf mongoose.

They found that different species exhibited varying degrees of kin discrimination, with the largest frequencies occurring among those who have the most to gain from cooperative interactions.

By-product benefit can also arise as a consequence of subordinate animals staying and helping a nest that is dominated by leaders who often suffer high mortality rates.

In a study published in 1995, scientists found that female lions showed individual differences in the extent to which they participated in group-territorial conflict.

There are three major mechanisms that generate this type of fitness benefit: limited dispersal, kin discrimination and the green-beard effect.

Hamilton originally suggested that high relatedness could arise in two ways: direct kin recognition between individuals or limited dispersal, or population viscosity, which can keep relatives together.

[19] The easiest way to generate relatedness between social partners is limited dispersal, a mechanism in which genetic similarity correlates with spatial proximity.

This mechanism has been shown in Pseudomonas aeruginosa bacteria, where cooperation is disfavored when populations are well mixed, but favored when there is high local relatedness.

Therefore, changes to the genome which prevent cancer (for example, by causing damaged cells to act co-operatively by destroying themselves) are favoured.

Multi-level selection theory contends that similar effects can occur, for example, to cause individuals to co-operate to avoid behaviours which favour themselves short-term, but destroy the community (and their descendants) long term.

In this interaction, rhizobia bacteria induce root nodule formation in legume plants via an exchange of molecular signals.

In fact, one-fifth of all known extant fungal species form obligate symbiotic associations with green algae, cyanobacteria or both.

Clearly (d) ("cooperation") is the best mutual strategy, but from the point of view of the individual betrayal is unbeatable (resulting in being set free, or getting only a two-year sentence).

[35] In the light of the iterated prisoner's dilemma game and the reciprocal altruism theory failing to provide full answers to the evolutionary stability of cooperation, several alternative explanations have been proposed.

Similarly, in amateur golf, better golfers have fewer strokes subtracted from their raw scores than the less talented players.

[42][43][44][45][46] This will have the effect of a sexual population rapidly shedding peripheral phenotypic features, thereby canalizing the entire outward appearance and behavior of all of its members.

They will all very quickly begin to look remarkably similar to one another in every detail, as illustrated in the accompanying photograph of the African pygmy kingfisher, Ispidina picta.

Once a population has become as homogeneous in appearance as is typical of most species, its entire repertoire of behaviors will also be rendered evolutionarily stable, including any cooperative, altruistic and social interactions.

[45] Its genes will therefore have only a very small probability of being passed on to the next generation, thus evolutionarily stabilizing cooperation and social interactions at whatever level of complexity is the norm in that population.

[34][47] One of the first references to animal cooperation was made by Charles Darwin, who noted it as a potential problem for his theory of natural selection.

Animals that practice group-living often benefit from assistance in parasite removal, access to more mates, and conservation of energy in foraging.

Rhizobia nodules on Vigna unguiculata
Cooperative hunting by wolves allows them to tackle much larger and more nutritious prey than any individual wolf could handle. However, such cooperation could, potentially, be exploited by selfish individuals who do not expose themselves to the dangers of the hunt, but nevertheless share in the spoils.
A male peacock with its beautiful but clumsy, aerodynamically unsound erectile tail, which Amotz Zahavi believes is a handicap, comparable to a race horse's handicap. The larger the handicap the more intrinsically fit the individual (see text).
The best horses in a handicap race carry the largest weights, so the size of the handicap is a measure of the animal's quality.
An African pygmy kingfisher , showing details of appearance and coloration that are shared by all African pygmy kingfishers to a high degree of fidelity. [ 41 ]