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At least 19 recordsLinked to original sources
PubMed1997

On the instability of evolutionary stable strategies.

Evolutionary stable strategies (ESSs) are often used to explain the behaviors of individuals and species. The analysis of ESSs determines which, if any, combinations of behaviors cannot be invaded by alternative strategies. However, two of the assumptions required to generate ESSs, an infinite population and payoffs described only on the average, are not particularly realistic in natural situations. Previous experiments have indicated that under more natural conditions of finite populations and stochastic payoffs, populations may evolve in trajectories that are unrelated to an ESS, even in very simple evolutionary games. Those earlier simulations are extended here under a variety of conditions. The results suggest that ESSs may not provide a good explanation of a finite population's behavior even when the conditions correspond closely with the infinite population model. The implications of these results are discussed briefly in light of previous literature claiming that ESSs generated suitable explanations of real-world data.

Animals↗
PubMed1994

The necessary and sufficient conditions of density-dependent evolutionary stable strategy (DDESS) in the two-phenotype model.

In this paper, we discuss the stability conditions of both the density-dependent pure and mixed strategy models of a polymorphic haploid population with only two pure strategies. Our results show that for the definition of density dependent evolutionary stable strategy DDESS and its stability. Cressman's frequency conditions are necessary and sufficient, and Cressman's density condition is not required.

Animals↗
PubMed1998

Evolutionary Stable Strategies and Trade-Offs in Generalized Beverton and Holt Growth Models.

A generalized Beverton-Holt model is considered in which a parameter gamma characterizes the onset of density dependence. An evolutionary stable strategy analysis of this parameter, reported in Getz (1996), is developed further here, using invasion exponents and the strategy dynamics of Vincent et al. (1993). The parameter gamma is also allowed to be density dependent, and it is shown that the most successful strategies of this type are those for which gamma is large for low densities and close to its minimum for high densities. A biological interpretation is given in the context of mobile females depositing their relatively sessile young on patches of resource, namely, females should overdisperse their young on resources when adult densities are high and underdisperse them when these densities are low. Finally the per capita growth rate parameter is also allowed to depend on gamma. It is shown that this dependence provides a mechanism by which periodic or chaotic attractor dynamics could evolve towards equilibrium attractor dynamics. Copyright 1998 Academic Press.

Journal Article↗
PubMed2003

Split sex ratios in perennial social Hymenoptera: a mixed evolutionary stable strategy from the queens' perspective?

In social Hymenoptera, relatedness asymmetries due to haplodiploidy often generate conflicts of genetic interest between queens and workers. Split sex ratios are common in ant populations and may result from such conflicts, with workers favoring the production of males in some colonies and of gynes in others. Such intercolonial differences may result from variations in relatedness asymmetries among colony members, but several examples are now known in which this hypothesis does not hold. We develop here a simple model assuming monogynous, monoandrous, worker-sterile, perennial colonies without dispersal restrictions. Workers may eliminate eggs of either sex and determine the caste of the female brood, but the queen controls the number of eggs of each sex she lays. In such conditions, we demonstrate that split sex ratios can result from queens adopting a mixed evolutionary stable strategy (ESS), with one option being to put a strict limit to the number of diploid eggs available and the alternative one to provide diploid eggs ad lib. In the former situation, workers should raise all diploid eggs as workers and release only male sexuals. In the latter, workers should adjust the caste ratio so as to reach the maximum sexual productivity for the colony, which is entirely invested into gynes. For a particular relative investment in gynes at the population level, between 0.5 (ESS under full queen control) and 0.75 (ESS under full worker control), an equilibrium is reached at which both strategies yield an equal genetic payoff to the queen. Male-specialized colonies are predicted to be equally abundant but less populous and less productive than gyne-specialized ones. Available data on the monogyne form of the fire ant, Solenopsis invicta, suggest that this model may apply in this case, although more specific studies are required to test these predictions.

Animals↗
PubMed2000

Evolutionary stable strategy: a test for theories of retroviral pathology which are based upon the concept of molecular mimicry.

The genetic makeup of animal and plant populations is determined by established principles and concepts. Ecology and evolution provide a basic theoretical framework for understanding how genetic changes occur in populations. Whether these rules can be applied to host retroviral populations is unknown. Individuals infected with the human immunodeficiency virus (HIV) contain within their bodies a viral population. This population is known as a viral quasispecies. Located in the transmembrane protein of HIV-1 is the viral sequence Gly-Thr-Asp-Arg-Val. Previous immunological studies have shown that viral antibody is produced in response to this five-amino-acid sequence. Antibody to this viral sequence also crossreacts and binds to a related peptide sequence found on certain immune cells. This related sequence, Gly-Thr-Glu-Arg-Val, is found on immune cells bearing a structure known as the major histocompatibility complex (MHC). The viral transmembrane sequence, Gly-Thr-Asp-Arg-Val, can be substituted with alanine residues utilizing site-directed mutagenesis. This creates a viral clone devoid of the genetic similarity with the MHC. Chimpanzees progressing to AIDS contain both sequences of interest. Suppression of the chimpanzee quasispecies utilizing anti-retroviral drugs is proposed. This action serves to suppress the presence of the viruses containing the sequence Gly-Thr-Asp-Arg-Val. When viral load has been reduced significantly, a drug resistant, alanine altered clone is to be introduced in large numbers. The concept of evolutionary stable strategy predicts that a viable HIV clone with alanine residues can genetically dominate the viral population. Immune system recognition of the alanine sequence is likely to result in renewed antibody production. Antibodies to the alanine containing viral sequence should not recognize or bind to the MHC. Immunological parameters can then be measured to determine the physiological impact of eliminating a sequence responsible for molecular mimicry between virus and host.

Acquired Immunodeficiency Syndrome↗
PubMed1990

An ESS-analysis for ensembles of prisoner's dilemma strategies.

The ESS (Evolutionary Stable Strategy) concept of Maynard Smith can be applied in its weak form to ensembles of competing PD ("Prisoner's Dilemma") strategies memorizing two to three of one's own and one's opponent's moves. The format of our study is: (1) games have very long duration; (2) Taylor-Jonker dynamics applies; (3) Effects of finite population size can be ignored. It is shown that in the case R greater than (T + S)/2 a set of strategies can be singled out which do not lose against any other strategy while co-operating with themselves. Such a set is uninvadable by other PD strategies if it constitutes more than half of the total population.

Biological Evolution↗
PubMed2002

Energy storage and the evolution of population dynamics.

We explore the mutual dependence of life history evolution and population dynamics by modeling a structured rotifer population that preys on a dynamic food supply. We focus on the ecological role of energy storage. A physiologically based submodel describes how individual predators allocate assimilated energy among growth, reproduction, and storage. We use invasibility analyses to predict evolutionary stable strategies for energy allocation. Various proxy measures of fitness based on measurable biological quantities, such as average population size or average per-capita fecundity, fail to predict evolutionary stable strategies. The predicted strategies indicate that selection strongly favors storage allocation for juveniles, but only for adults when prey densities are high. With the evolution of energy storage, population dynamics can shift from aperiodic to stable cycles without any need to invoke group selection.

Animals↗
PubMed1988

Sex ratio polymorphism: the impact of mutation and drift on evolution.

This paper addresses the question, which sex ratio will evolve in a population that is subject to mutation and drift. The problem is analyzed using a simulation model as well as analytical methods. A detailed simulation model for the evolution of a population's allele distribution shows that for the sex ratio game a wide spectrum of different population states may evolve from on the one hand a monomorphic state with one predominant allele and with all other alleles suppressed by the forces of selection, to on the other hand a polymorphism determined by recurrent mutations. Which of these states will evolve depends on the population size, the mating system and the rate of mutations. For the sex ratio game the evolutionary stable strategy (ESS), as defined by evolutionary game theory, can only predict the population sex ratio but not the underlying stable population state. A comparison of different approaches to the problem shows that false predictions of the stable population states might result from two simplifying assumptions that are fairly common in evolutionary biology: a) it is assumed that mutations are rare events and there is never more than one mutant gene present in a population at any one time; b) a deterministic relationship is assumed between the fitness assigned to an individual's strategy and the individual's contribution to the gene pool of future generations.

Animals↗
PubMed2006

Predation and cathemerality. Comparing the impact of predators on the activity patterns of lemurids and ceboids.

The removal, or absence, of predatory species could be a contributing proximate factor to the rise of primate cathemerality. But predators themselves can also be cathemeral, so cathemerality could well be an evolutionary stable strategy. From a comparative perspective, it appears that the effect of predatory species cannot provide a unitary explanation for cathemerality. Varying distributions and population densities of predators, especially raptors, may be key factors in owl monkey (Aotus) cathemerality, but temperature and lunar cycle variation have also been implicated. In Madagascar, while raptors are potential predators of lemur species, the cathemerality of Eulemur species coincides with that of the fossa (Cryptoprocta ferox), a major predatory threat to lemurs. Thus, lemurid cathemerality may be more parsimoniously explained as an evolutionary stable strategy.

Animals↗
PubMed1982

Assortment of encounters and evolution of cooperativeness.

The method of evolutionary stable strategies (ESS), in its current form, is confronted with a difficulty when it tries to explain how some social behaviors initiate their evolution. We show that this difficulty may be removed by changing the assumption made tacitly in game theory (and in ESS) of randomness of meetings or encounters. In reality, such randomness seems to be rare in nature. Family, population and social structure, customs, and habits impose various types of deviation from randomness. Introducing nonrandomness of meeting in a way formally similar to assortative mating, we show that the bar to initial increase of inherited cooperative or altruistic behaviors can be removed, provided there is sufficient assortment of meetings. Family structure may cause contacts predominantly between certain types of relatives, and one can reconstruct some results of classical kin selection in terms of evolutionary stable strategy with assortative meetings. Neighbor effects and group selection might be similarly treated. Assortment need not be a passive consequence of population and social structure, but it can also be actively pursued. Behaviors favoring the choice of cooperative companions will have the effect of favoring the evolution of cooperativeness. It can be shown that discrimination in the choice of companions, especially if combined with assortment, can favor the development of cooperativeness, making initial increase of cooperative behavior possible even at levels of assortment passively imposed which would not be adequate, per se, to guarantee the increase of cooperativeness. It is possible that, in some cases, cooperativeness and behavior favoring some type of assortment are coselected.

Journal Article↗
PubMedDate not supplied

Required parental investment and mating patterns: a quantitative analysis in the context of evolutionarily stable strategies.

Much social psychological research has been dedicated to understanding mating strategies from the standpoint of genetic-fitness payout (e.g., Simpson and Gangestad, 2000). The current work is designed to provide a coherent, quantitative model for predicting different classes of mating strategies in both males and females. Specifically, the framework developed in this paper is an elaboration of Dawkins' (1989) quantitative assessment of different male and female mating strategies. Dawkins suggests that the prevalence of different strategies employed should be predictable in terms of evolutionary stable strategies. In the current work, a quantitative analysis predicting the prevalence of different mating strategies within each sex was conducted. The mathematical functions derived suggest that variability in the costs associated with raising offspring affects the expected prevalence of mating strategies differently for males and females. According to the present model, variability in female strategies should be less affected by changes in parental investment (PI) than variability in male strategies. Important predictions regarding male and female mating strategies across cultures are discussed.

Biological Evolution↗
PubMed1994

Koinophilia.

This paper is concerned with the evolution of the species phenotype (morphology and behaviour) when sexual organisms identify mutant traits by their unusual (or rare) appearance. Mate-seeking individuals are assumed, however, to have no means of distinguishing the occasional beneficial mutation from the others. We show that the resulting preference for mates with predominantly common traits (koinophilia) transforms the prevailing phenotype (as perceived by conspecifics) into an evolutionary stable strategy (ESS), as defined by Maynard-Smith (1974). This has far reaching evolutionary implications, permitting, in particular, the evolution of true "group adaptations". A subsidiary finding shows that koinophilia always has a substantial, immediate, selective advantage over panmixis, rendering koinophilia, itself, an ESS with respect to panmixis. This is particularly pronounced when the mutation rate is high, but beneficial mutations with high fitnesses are rare. The mean fitness of mutations has only a minor effect on the relative advantage of koinophilia.

Adaptation, Physiological↗
PubMed2002

Evolution of cannibalistic traits: scenarios derived from adaptive dynamics.

The evolution of cannibalistic traits in consumer populations is studied in this paper with the approach of adaptive dynamics theory. The model is kept at its minimum complexity by eliminating some environmental characteristics, like heterogeneity and seasonalities, and by hiding the size-structure of the population. Evolutionary dynamics are identified through numerical bifurcation analysis, applied both to the ecological (resident-mutant) model and to the canonical equation of adaptive dynamics. The result is a rich catalog of evolutionary scenarios involving evolutionary stable strategies and branching points both in the monomorphic and dimorphic dynamics. The possibility of evolutionary extinction of highly cannibalistic populations is also ascertained. This allows one to explain why cannibalism can be a transient stage of evolution.

Adaptation, Physiological↗
PubMed1997

Revisiting Strategic Models of Evolution: The Concept of Neighborhood Invader Strategies

In game-theoretic or strategic models of species evolution, the phenotype of individual organisms in a population are regarded as alternate strategies for playing a competitive game. The evolutionary outcome is predicted to conform to the "solution" of that game. The most usual solution concept adopted for the evolutionary game is that of Maynard Smith, the so-called "evolutionary stable strategies" (ESS). In this paper we explore an alternative solution concept. We call it neighborhood invader strategy (NIS). A NIS is a phenotype which is capable of invading all established populations of its neighbors. This phenotype need not be, at the same time, an ESS; and the reverse is true as well. We shall analyze this concept for a single species whose evolutionary-possibility set is a one-dimensional continuum. Copyright 1997 Academic Press

Journal Article↗