"I have a hunch that we may come to look back on the invention of the ESS concept as one of the most important advances in evolutionary theory since Darwin."
Intra species interactions between individuals in a population tend to occur more often then those with other species. This is because they live almost identical lives, half the population are potential mates, and they compete for all the same resources. This chapter is about agression, it discusses the complex reasons why a particular individual might be better off not killing one of its own species to get a leg up in the short term. Without using excessive mathematics, Dawkins introduces how Game Theory can be used to better understand the cost-benefit relationship with aggression between organisms.
The concept of evolutionarily stable strategy (ESS) is defined as "a strategy which, if most members of a population adopt it, cannot be bettered by an alternative strategy."Now in his first example, he discusses how two fighting strategies (hawk and dove) within a population would become genetically stable in a specific (7:5) ratio. Although having the entire population solely using the dove strategy would be much more productive, unconscious gene machines do not have foresight in the long term and thus using a single strategy would be very easy to exploit by one individual.
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Dawkins then adds a conditional strategist called the retaliator that acts in response to what he is matched up with. He also adds a bully to the mix that acts like a hawk in all situations until someone fights back as well as a prober-retaliator which acts basically like the retaliator but tends to escalate the fight as a hawk. In a mixed population of all of these individuals we would find that retaliator would prove the most stable strategy, with prober-retaliator not far behind. Smaller proportions of each other type would then oscillate in the population. These types do not have to be seen as distinct polymorphisms but as a combined mix of all in each individual.
What is usually misconceived here is that group selection would drive the alleles of the most productive strategy to spread across the population thus increasing the population. Unfortunately ESS shows us that the most productive strategy might not be completely stable.
We then move on to an explanation of the war of attrition and how one's knowing another's strategy is unstable and is easily exploited by a mutant. Then comes along the poker face, we have a general average price that one should pay (fight, stand-ground for) but each individual has no idea what another will pay. The poker face is stable in this way.
Now, how does asymmetrical contests mont up with ESS? One example is a resident vs. an intruder. On one side, if intruded, fight back and on the other, if intruded, retreat. In this case, it depends on who gets to the majority first, after that deviations are penalized. In reality, we see that a territorial defense of a resident is naturally the ESS for many reasons.
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