Social evolution 4

Byproduct benefits

Non-enforced benefit of cooperation. When benefit to others occurs as a side effect of acting selfishly.

Grouping/herding animals less likely to be attacked in larger groups and when clustered together. Vultures gain food left over from lion kills.

Example of byproduct benefits

Feedback benefits

Non-enforced benefit of cooperation. When aiding another generates benefits which are returned. Benefits returned must outweigh costs of cooperating.

Honey guides leading humans to beehives. Endosymbiosis in eukaryotic cells. Chromosomes and genes acting in same direction.

Examples of feedback benefits

Reciprocal altruism

Enforced benefit of cooperation. Where partners exchange benefits.

Vampire bats form partnerships and feed each other blood if one has drunk more than necessary and the other hasn't fed.

Example of reciprocal altruism.

Reward-based cooperation

Enforced benefit of cooperation. Where cooperation on the part of the actor is rewarded by the recipient.

Nectar in return for pollination in plant-pollinator relationships. Female Japanese macaques reward grooming by their partner with sex.

Examples of reward-based cooperation

Punishment and policing

Enforced benefit of cooperation. Where failure to cooperate on the part of the actor is punished by the recipient. Possibly cheaper than rewards as must only bear cost of punishing when cooperation doesn't occur.

Dominant male pig-tailed macaques break up fights and troublesome coalitions. Bobtail squid house luminous Vibrio fischeri bacteria and produce enzymes which are toxic when the bacteria do not produce luciferase. CRISPR in E. coli enforces genetic integri

Examples of punishment and policing.

Workers with monogamous queens have relatedness of 0.75 to the queen's daughters, while those with polyandrous queens have relatedness of 0.25 to the queen's daughters. Monogamy is ancestral to all 8 groups of eusocial insects.

Reason for origins of eusociality in insects.

In single-mated colonies, workers are more related to other workers' sons than queen's sons, so kill queen's sons. In multiple-mated colonies, workers more related to queen's sons than workers' sons, so police other workers.

Reason for derived polyandry in eusocial insects.