Evolutionary Stable Strategies are behavioural strategies that if adopted by all individuals in a population then it cannot be replaced by a different strategy through natural selection. I was very fascinated by an article that explores how evolutionary stable strategies develop within a population over the span of generations using Game Theory and can help understand why it is important to help others for our own long-term survival. Moreover, the article also touches on concepts of Game Theory discussed in class such as payoff matrix and shows the implications of cooperation.
The articles observes two organisms that have a mutually beneficial relationship and develops a payoff matrix . Legume (bean plant) depends on bacteria that lives within the plant for nitrogen that the plant can use for photosynthesis to produce more sugars and the bacteria relies on the plant for energy in the form of sugar. If both organisms cooperate, they both can benefit creating a positive feedback for cooperation. The payoff matrix defined for the interaction is defined below:
If an organism cheats, the benefit in the next interaction is reduced by modifier value (m) – result for cheating. Whereas, if both organisms cooperate, their benefit is increased by (m) in the next interaction. Modifier values in payoffs can greatly impact behaviour allowing organisms to cooperate for better results.
The image on the right shows that even though only ~25% of the population of organisms were cooperating at the beginning, that quickly jumped to almost the entire population over the span of 1000 generations of both organisms showing the power of payoff modification in developing Evolutionary Stable Strategies if the partners honestly reciprocate cooperation from the other organism.
Game Theory provides us a framework to understand evolution of complex biological interactions across multiple generations and explains tendency for altruistic behavioural strategies like a bird providing warning call to other birds temporarily putting itself in danger and hoping that other birds will give it a warning call in future of an immediate threat – therefore it prepares to be at a disadvantage for a short amount of time hoping it will improve the bird’s chances of survival over its life span. Therefore, Game Theory helps to demonstrate that evolution of cooperation is necessary for long-term survival.
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