Editing Evolutionarily stable strategy (section)

{{Short description|Solution concept in game theory}}
{{Infobox equilibrium
|name          = Evolutionarily stable strategy
|subsetof      = [[Nash equilibrium]]
|supersetof    = [[Stochastically stable equilibrium]], Stable [[Strong Nash equilibrium]]
|intersectwith = [[Subgame perfect equilibrium]], [[Trembling hand perfect equilibrium]], [[Perfect Bayesian equilibrium]]|
|discoverer    = [[John Maynard Smith]] and [[George R. Price]]
|example       = [[Hawk-dove]]
|usedfor       = [[Biology|Biological modeling]] and [[Evolutionary game theory]]
}}
{{Redirect-distinguish|Evolutionary strategy|Evolution strategy}}
An '''evolutionarily stable strategy''' ('''ESS''') is a [[strategy (game theory)|strategy]] (or set of strategies) that is ''impermeable'' when adopted by a [[population genetics|population]] in adaptation to a specific environment, that is to say it cannot be displaced by an alternative strategy (or set of strategies) which may be novel or initially rare. Introduced by [[John Maynard Smith]] and [[George R. Price]] in 1972/3,<ref name="OEJMS">{{cite book |author=Maynard Smith, J. |author-link=John Maynard Smith |chapter=Game Theory and The Evolution of Fighting |title=On Evolution |publisher=Edinburgh University Press |year=1972 |isbn=0-85224-223-9 |url-access=registration |url=https://archive.org/details/onevolution0000mayn }}</ref><ref name="JMSandP73">{{cite journal |doi=10.1038/246015a0 |author1=Maynard Smith, J. |author-link1=John Maynard Smith |author2=Price, G.R. |author-link2=George R. Price |title=The logic of animal conflict |journal=Nature |volume=246 |issue=5427 |pages=15–8 |year=1973 |bibcode=1973Natur.246...15S}}</ref> it is an important concept in [[behavioural ecology]], [[evolutionary psychology]], [[Game theory|mathematical game theory]] and [[economics]], with applications in other fields such as [[anthropology]], [[philosophy]] and [[political science]].

In game-theoretical terms, an ESS is an [[equilibrium refinement]] of the [[Nash equilibrium]], being a Nash equilibrium that is also "evolutionarily [[Ecological stability|stable]]." Thus, once [[Fixation (population genetics)|fixed]] in a population, [[natural selection]] alone is sufficient to prevent alternative ([[mutant]]) strategies from replacing it (although this does not preclude the possibility that a better strategy, or set of strategies, will emerge in response to selective pressures resulting from environmental change).