Evolutionarily Stable Strategies

Ecology ◽  
2019 ◽  
Author(s):  
Michael D. Breed

Evolutionarily stable strategies (ESS) are phenotypes that persist in populations over evolutionary time and cannot be replaced by invading strategies. Cases in which alternative strategies coexist stand as being of particular interest. Evolutionary biologists were introduced to the concept of ESS through the efforts of John Maynard Smith and George R. Price, whose work remains the keystone expression of this concept. Maynard Smith and Price dealt with animal conflicts, in which combatants may have differing strategies and physical abilities. The stability of evolutionary strategies is often analyzed using the tools of game theory, which allows determination of the persistence of strategies when played against one another. Game theory also opens the door to assessing the potential success of novel strategies upon introduction into a population. ESS often coincide with the Nash equilibrium, a game theory concept that describes conditions under which cognitively aware players in a game cannot gain by changing their individual strategy. In addition to animal conflict, analyses of ESS have been applied in a wide variety of evolutionary contexts and indeed are applicable whenever alternative heritable phenotypes are present. One possibility is that ESS occur as alternative genotypes within populations and thus should be analyzed using population-genetic approaches. ESS can also be conditionally expressed by individuals, depending on environmental and social context. This second option also requires a genotypic basis for strategies but allows for more strategical complexity through responses that may shift over developmental time or with experience. Interspecific interactions are an additional context for ESS, in which ESS drive evolutionary arms races between predators and prey or hosts and diseases or parasites. Maynard Smith and Price built on a conceptual framework in evolutionary ecology developed by William D. Hamilton in studies of kin selection, sex ratios, and herding behavior, and by Geoff Parker, working on sperm competition. ESS offer convenient latticework for thinking about many ecological and evolutionary trade-offs in which organisms balance costs and benefits of potential strategic choices in development and behavior, either in within-generation decision-making or between-generation evolution.

2019 ◽  
Vol 21 (04) ◽  
pp. 1950005
Author(s):  
Elvio Accinelli ◽  
Filipe Martins ◽  
Jorge Oviedo

In this paper, we study the concept of Evolutionarily Stable Strategies (ESSs) for symmetric games with [Formula: see text] players. The main properties of these games and strategies are analyzed and several examples are provided. We relate the concept of ESS with previous literature and provide a proof of finiteness of ESS in the context of symmetric games with [Formula: see text] players. We show that unlike the case of [Formula: see text], when there are more than two populations an ESS does not have a uniform invasion barrier, or equivalently, it is not equivalent to the strategy performing better against all strategies in a neighborhood. We also construct the extended replicator dynamics for these games and we study an application to a model of strategic planning of investment.


Author(s):  
Sam Ganzfried

Evolutionarily stable strategy (ESS) is an important solution concept in game theory which has been applied frequently to biology and even cancer. Finding such a strategy has been shown to be difficult from a theoretical complexity perspective. Informally an ESS is a strategy that if followed by the population cannot be taken over by a mutation strategy. We present an algorithm for the case where mutations are restricted to pure strategies. This is the first positive result for computation of ESS, as all prior results are computational hardness and no prior algorithms have been presented.


2020 ◽  
pp. 261-272
Author(s):  
John M. McNamara ◽  
Olof Leimar

Important areas for future developments of game theory in biology are put forward. These include several issues that are dealt with in the book, such as trait co-evolution, the consequences of variation, time structure, and the embedding of games into an ecological context and into the lives of individuals. New areas are also suggested, with Tinbergen’s four questions about the study of animal behaviour serving as a starting point. Game theory could be combined with phylogenetic analysis by examining how Evolutionarily Stable Strategies (ESSs) might change over evolutionary time, including major shifts between different ESSs, which might correspond to different species over evolutionary time. Concerning behavioural mechanisms in large worlds, the question of which mechanism parameters that are tuned by evolution is addressed, with a brief summary of the current knowledge about comparative cognition. The possible importance of limited flexibility in mechanisms is illustrated by outlining a model of a trust game. Finally, the potential for game theory to contribute to the study of cognitive development is discussed, using mutualism between cleaner fish and their client fish as an illustration.


Mathematics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 805
Author(s):  
Leyi Shi ◽  
Xiran Wang ◽  
Huiwen Hou

Honeypot has been regarded as an active defense technology that can deceive attackers by simulating real systems. However, honeypot is actually a static network trap with fixed disposition, which is easily identified by anti-honeypot technology. Thus, honeypot is a “passive” active defense technology. Dynamic honeypot makes up for the shortcomings of honeypot, which dynamically adjusts defense strategies with the attack of hackers. Therefore, the confrontation between defenders and attackers is a strategic game. This paper focuses on the non-cooperative evolutionary game mechanism of bounded rationality, aiming to improve the security of the array honeypot system through the evolutionarily stable strategies derived from the evolutionary game model. First, we construct a three-party evolutionary game model of array honeypot, which is composed of defenders, attackers and legitimate users. Secondly, we formally describe the strategies and revenues of players in the game, and build the three-party game payoff matrices. Then the evolutionarily stable strategy is obtained by analyzing the Replicator Dynamics of various parties. In addition, we discuss the equilibrium condition to get the influence of the number of servers N on the stability of strategy evolution. MATLAB and Gambit simulation experiment results show that deduced evolutionarily stable strategies are valid in resisting attackers.


Genetics ◽  
1989 ◽  
Vol 121 (4) ◽  
pp. 877-889
Author(s):  
A B Harper

Abstract The theory of evolutionarily stable strategies (ESS) predicts the long-term evolutionary outcome of frequency-dependent selection by making a number of simplifying assumptions about the genetic basis of inheritance. I use a symmetrized multilocus model of quantitative inheritance without mutation to analyze the results of interactions between pairs of related individuals and compare the equilibria to those found by ESS analysis. It is assumed that the fitness changes due to interactions can be approximated by the exponential of a quadratic surface. The major results are the following. (1) The evolutionarily stable phenotypes found by ESS analysis are always equilibria of the model studied here. (2) When relatives interact, one of the two conditions for stability of equilibria differs between the two models; this can be accounted for by positing that the inclusive fitness function for quantitative characters is slightly different from the inclusive fitness function for characters determined by a single locus. (3) The inclusion of environmental variance will in general change the equilibrium phenotype, but the equilibria of ESS analysis are changed to the same extent by environmental variance. (4) A class of genetically polymorphic equilibria occur, which in the present model are always unstable. These results expand the range of conditions under which one can validly predict the evolution of pairwise interactions using ESS analysis.


Author(s):  
Swati Srivastava

Abstract This research note unveils new archival evidence from Amnesty International's first twenty-five years (1961–1986) to shed light on the realization of international human rights as Amnesty balanced “nonpolitical politics” through multifaceted government relations. The research draws from minutes and reports of eighty meetings of Amnesty's executive leadership and interviews from the 1983 to 1985 Amnesty Oral History project, all collected from the International Institute of Social History. The records show that during this time Amnesty relied on government and foundation funding to exit a severe financial crisis. Amnesty also cultivated a private diplomatic network with governments for access and advocacy and conducted side bargains with closed countries for access and reforms. In one sense, the new evidence complicates the conventional wisdom that Amnesty was only financed from small, individual donors and stayed away from private government dealings. In another sense, the new data extend existing insights about INGO strategic action by revealing Amnesty's pragmatic trade-offs when maintaining arms–length relations with governments to better appreciate the organization's early challenges and accomplishments. The note ultimately contributes to scholarship on the strategic choices of INGOs and provides new data for future research on the agency of nonstate actors in global governance navigating complex government relations. Esta nota de investigación presenta nueva evidencia documental de los primeros 25 años de Amnistía Internacional (Amnesty International), de 1961 a 1986, para arrojar luz sobre el cumplimiento de las normas internacionales de derechos humanos mientras Amnistía balanceaba la “política no política” mediante relaciones gubernamentales polifacéticas. La investigación incorpora actas e informes de 80 reuniones del liderazgo ejecutivo de Amnistía y entrevistas de 1983 a 1985 del proyecto Historia Oral de Amnistía (Amnesty Oral History), recopiladas del Instituto Internacional de Historia Social. Los documentos muestran que, en ese momento, Amnistía necesitó financiación gubernamental y de fundaciones para salir de una crisis financiera grave. Amnistía también cultivó una red diplomática privada con gobiernos a cambio de acceso y defensa, y tuvo negocios paralelos con países cerrados a cambio de acceso y reformas. En un sentido, la nueva evidencia complica la sabiduría convencional de que Amnistía solo tuvo financiamiento de donantes pequeños e individuos y se mantuvo lejos de los negocios privados con gobiernos. En contraste, los nuevos datos amplían las percepciones existentes sobre la acción estratégica de organizaciones no gubernamentales internacionales (ONGI), revelando las concesiones pragmáticas de Amnistía al mantener relaciones independientes con gobiernos, y permiten apreciar mejor los desafíos y logros iniciales de la organización. La nota, fundamentalmente, contribuye a la investigación sobre las decisiones estratégicas de las ONGI y brinda nuevos datos para futuras investigaciones sobre la autonomía de los actores no estatales que navegan relaciones gubernamentales complejas en la gobernanza global. Cet exposé de recherche dévoile de nouvelles preuves issues des 25 premières années d'archives d'Amnesty International (1961–1986) pour apporter un éclairage sur l'application des droits de l'Homme tandis qu'Amnesty équilibrait la « politique apolitique » par le biais de relations gouvernementales à plusieurs facettes. Cette recherche s'appuie sur des minutes et rapports de 80 réunions de la haute direction d'Amnesty, ainsi que sur des entretiens qui ont eu lieu entre 1983 et 1985 dans le cadre du projet Oral History (Histoire orale) d'Amnesty. Ces données ont toutes été recueillies auprès de l'Institut International d'Histoire Sociale. Les archives montrent que durant cette période, Amnesty a dû compter sur le financement de gouvernements et de fondations pour sortir d'une grave crise financière. Amnesty a également cultivé un réseau diplomatique privé avec des gouvernements pour faciliter son accès et son plaidoyer dans le pays concerné tout en menant des négociations parallèles avec les pays fermés pour y favoriser son accès et les réformes. En un sens, les nouvelles preuves compliquent les idées reçues selon lesquelles Amnesty ne serait financée que par de petits donateurs individuels et resterait à l’écart des affaires gouvernementales privées. Mais en un autre sens, ces nouvelles données enrichissent les renseignements existants sur l'action stratégique des organisations non gouvernementales internationales en révélant qu'Amnesty s’était livrée à des compromis pragmatiques en entretenant des relations avec les gouvernements tout en restant à distance. Ces renseignements nous permettent donc de mieux apprécier les premiers défis et accomplissements de l'organisation. En définitive, cet exposé contribue aux études sur les choix stratégiques des organisations non gouvernementales internationales et fournit de nouvelles données pour les recherches futures sur l'intervention des acteurs non étatiques dans la gouvernance mondiale tandis qu'ils naviguent dans des relations gouvernementales complexes.


1980 ◽  
Vol 17 (2) ◽  
pp. 559-562 ◽  
Author(s):  
Andris Abakuks

It is pointed out that the conditions given by Haigh (1975) for finding evolutionarily stable strategies corresponding to a given matrix are sufficient, but not always necessary. An example is given, and an amended version of the necessary and sufficient conditions is stated.


2021 ◽  
Author(s):  
Xiao Zhang ◽  
Yaqi Hao ◽  
Daizhan Cheng

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