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Papers by István Scheuring

Ecology Letters, 2011

We review recent work at the interface of economic game theory and evolutionary biology that prov... more We review recent work at the interface of economic game theory and evolutionary biology that provides new insights into the evolution of partner choice, host sanctions, partner fidelity feedback and public goods. (1) The theory of games with asymmetrical information shows that the right incentives allow hosts to screen-out parasites and screen-in mutualists, explaining successful partner choice in the absence of signalling. Applications range from ant-plants to microbiomes. (2) Contract theory distinguishes two longstanding but weakly differentiated explanations of host response to defectors: host sanctions and partner fidelity feedback. Host traits that selectively punish misbehaving symbionts are parsimoniously interpreted as pre-adaptations. Yucca-moth and legume-rhizobia mutualisms are argued to be examples of partner fidelity feedback. The theory of public goods shows that cooperation in multi-player interactions can evolve in the absence of assortment, in one-shot social dilemmas among non-kin. Applications include alarm calls in vertebrates and exoenzymes in microbes.

ABSTRACT A pályázat keretében végzett kutatásaink a következő elméleti témakörökben történtek: 1)... more ABSTRACT A pályázat keretében végzett kutatásaink a következő elméleti témakörökben történtek: 1) Párosodási típusok evolúciója térben explicit modellel 2) Korai evolúciós problémák vizsgálata 3) A diszperzió és a mutualizmus evolúciója 4) Metapopulációk erősen zajos környezetben 5) Az interferencia-kompetíció szerepe mikrobiális élet-közösségek diverzitásának fenntartásában 6) Táplálékhálózatok szerkezete és stabilitása. Ebben a hat témakörben összesen 38, a pályázat azonosító számának feltüntetésével megjelent publikáció született, melyek összesített impakt faktora 113.86. Mindegyik témában folytatjuk a kutatásokat. | We have accomplished research in the following theoretical topics with the support of the present grant: 1) The evolution of mating types in a spatially explicit model 2) Research on problems of early evolution 3) The evolution of dispersal and mutualism 4) The dynamics of metapopulations in very noisy environments 5) The role of interference competition in the maintenance of the diversity of microbial communities 6) The strucure and the stability of food webs We have published 38 papers on these six topics with the number of the grant mentioned in the Acknowledgements of the papers. The cumulative impact factor of these publications is 113.86. We are planning to continue research in all the six topics.

Journal of Theoretical Biology, 2013

The existence of cooperation between species raises a fundamental problem for evolutionary theory... more The existence of cooperation between species raises a fundamental problem for evolutionary theory. Why provide costly services to another species if the feedback of this provision also happens to benefit intra-specific competitors that provide no service? Rewarding cooperators and punishing defectors can help maintain mutualism; this is not possible, however, when one can only respond to the collective action of one's partners, which is likely to be the case in many common symbioses. We show how the theory of public goods can explain the stability of mutualism when discrimination between cooperators and defectors is not possible: if two groups of individuals trade goods that are non-linear, increasing functions of the number of contributions, their mutualistic interaction is maintained by the exchange of these public goods, even when it is not possible to punish defectors, which can persist at relatively high frequencies. This provides a theoretical justification and testable predictions for the evolution of mutualism in the absence of discrimination mechanisms.

ABSTRACT Pályázatunk elsősorban a kooperáció eredetének számos aspektusát, továbbá a komunikációs... more ABSTRACT Pályázatunk elsősorban a kooperáció eredetének számos aspektusát, továbbá a komunikációs rendszerek őszinteségét fenntartó mechanizmusok tanulmányozta. Az elméleti munkák mellett e témakörben humán és állatkísérleteket is elindítottunk. Rámutattunk az olcsó vagy költségmentes kommunikáció őszinteségét fenntartó ökológiai tényezőkre. Megmutattuk például, hogy az emberi kooperáció és az őszinte kommunikáció evolúciója szoros kapcsolatban lehet, illetve állati társadalmakban a kommunikácó őszinteségét a kompetíció erőssége is befolyásolhatja. Vizsgáltuk az ember és a kutya kooperációjának kommunikációs sajátságait. Megmutattuk, hogy a préda-perdátor vagy gazda-parazita kölcsönhatások ismerete szükséges számos kooperatív viselkedés evolúciójának értelmezéséhez. Például a predációs nyomás okozhatja a prédák altruista viselkedését, vagy a kasztrációs parazitát éppen a mutualista társ jelenléte szabályozza. Számos tanulmányban az egyedek térbeli elhelyezkedésének és korlátozott mozgásának a kooperáció evolúciójára kifejtett hatását vizsgáltuk. Több olyan munkánk is született, ahol a humán kommunikáció illetve kooperáció sajátságait a többszintű szelekciós modellek segítségével értelmeztük. Sikerült kiépítsünk egy számítógépes labort, mellyel a jövőben s humán etológiai kísérleteket tudunk végezni. A kutatás legfontosabb eszközének számító evolúciós játékelméletben számos alapkutatás jellegű eredményünk is született, a sztochasztikus elmélet fejlesztésétől a többfajos elméletig. | Our project mainly focused on several aspects of the evolution of cooperation and of the mechanisms maintaining honesty in communicating systems. Beside theoretical works we started animal and human experiments as well. We reveal ecological backgrounds maintaining honesty of cheap or costless communication in numerous systems. It is shown for example that the origin of human cooperation and reliable information processing can be in close connection to each other, and that strength of competition modifies the level of honesty in animal communities. We studied the characteristics of communication in the case of human-dog cooperation. We have shown that characteristics of predator-prey or host-parasite interactions are required to explain evolution of cooperative behaviour in numerous cases. For example, predation load can cause altruistic predator defence among preys, or a mutualistic competitor can control castrating parasites. Several papers focused on the spatial aspects and limited migration of individuals on the evolution of cooperation. Other works emphasized that characteristics of human cooperation can be explained by multilevel selection. We set up a computer lab, which could be a basis of a series of human behavior experiment in the near future. We have significant purely theoretical results in the field of our primary mathematical method, that is of evolutionary game theory; from the development of stochastic theory to the multi-species theory.

Journal of Theoretical Biology, 1997

A simple metapopulation lattice model of two competing phenotypes is presented, where one phenoty... more A simple metapopulation lattice model of two competing phenotypes is presented, where one phenotype reacts more sensitively to overcrowding by migrating to neighboring local habitats. The sensitivity is formulated by means of a threshold density of the subpopulations, above which dispersal is triggered off. If this threshold density is not very far from the local carrying capacity, an increased mobility provides benefits on the metapopulation level. At a surprisingly small difference between migrational triggering thresholds, the phenotype of larger mobility (or lower threshold) squeezes out the less mobile one from the whole system in a wide parameter range. Evolutionary considerations give an optimal threshold level for our model metapopulation.

Chaos, 2002

We have analyzed the dynamics of metabolically coupled replicators in open chaotic flows. Replica... more We have analyzed the dynamics of metabolically coupled replicators in open chaotic flows. Replicators contribute to a common metabolism producing energy-rich monomers necessary for replication. The flow and the biological processes take place on a rectangular grid. There can be at most one molecule on each grid cell, and replication can occur only at localities where all the necessary replicators

Community Ecology, 2003

... However, only little experience has been accumulated on observer errors inherent in field est... more ... However, only little experience has been accumulated on observer errors inherent in field estima-tions (Sykes et al 1983, Gotfryd and Hansell 1985, Ken-nedy and Addison 1987, Lepš and Hadincová 1992, Klimeš et al 2001). ... I. Hahn 1 and I. Scheuring 1,2 ...

A generalized version of the N-person Volunteer's Dilemma Game (NVD) has been suggested recently ... more A generalized version of the N-person Volunteer's Dilemma Game (NVD) has been suggested recently for illustrating the problem of N-person social dilemmas. Using standard replicator dynamics it can be shown that coexistence of cooperators and defectors is typical in this model. However, the question of how a rare mutant cooperator could invade a population of defectors is still open.

Theoretical ecologists have observed chaotic behavior in population models for decades. However, ... more Theoretical ecologists have observed chaotic behavior in population models for decades. However, in the past few years, several studies indicate that complex dynamics, including chaos, become less probable in biologically more sophisticated models. For example, the inclusion of either sexual reproduction, population structure or dispersal generally increases stability. These results can explain the difference between the dynamical complexity of most theoretical models and the relative stability found within real time series.

Journal of theoretical biology, Jan 7, 2005

Laboratory experiments and numerical simulations have shown that the outcome of cyclic competitio... more Laboratory experiments and numerical simulations have shown that the outcome of cyclic competition is significantly affected by the spatial distribution of the competitors. Short-range interaction and limited dispersion allows for coexistence of competing species that cannot coexist in a well-mixed environment. In order to elucidate the mechanisms that destroy species diversity we study the intermediate situation of imperfect mixing, typical in aquatic media, in a model of cyclic competition between toxin producing, sensitive and resistant phenotypes. It is found, that chaotic mixing, by changing the character of the spatial distribution, induces coherent oscillations in the populations. The magnitude of the oscillations increases with the strength of mixing, leading to the extinction of some species beyond a critical mixing rate. When mixing is non-uniform in space, coexistence can be sustained at much stronger mixing by the formation of partially isolated regions, that prevent glo...

Ecology Letters, 2011

We review recent work at the interface of economic game theory and evolutionary biology that prov... more We review recent work at the interface of economic game theory and evolutionary biology that provides new insights into the evolution of partner choice, host sanctions, partner fidelity feedback and public goods. (1) The theory of games with asymmetrical information shows that the right incentives allow hosts to screen-out parasites and screen-in mutualists, explaining successful partner choice in the absence of signalling. Applications range from ant-plants to microbiomes. (2) Contract theory distinguishes two longstanding but weakly differentiated explanations of host response to defectors: host sanctions and partner fidelity feedback. Host traits that selectively punish misbehaving symbionts are parsimoniously interpreted as pre-adaptations. Yucca-moth and legume-rhizobia mutualisms are argued to be examples of partner fidelity feedback. The theory of public goods shows that cooperation in multi-player interactions can evolve in the absence of assortment, in one-shot social dilemmas among non-kin. Applications include alarm calls in vertebrates and exoenzymes in microbes.

ABSTRACT A pályázat keretében végzett kutatásaink a következő elméleti témakörökben történtek: 1)... more ABSTRACT A pályázat keretében végzett kutatásaink a következő elméleti témakörökben történtek: 1) Párosodási típusok evolúciója térben explicit modellel 2) Korai evolúciós problémák vizsgálata 3) A diszperzió és a mutualizmus evolúciója 4) Metapopulációk erősen zajos környezetben 5) Az interferencia-kompetíció szerepe mikrobiális élet-közösségek diverzitásának fenntartásában 6) Táplálékhálózatok szerkezete és stabilitása. Ebben a hat témakörben összesen 38, a pályázat azonosító számának feltüntetésével megjelent publikáció született, melyek összesített impakt faktora 113.86. Mindegyik témában folytatjuk a kutatásokat. | We have accomplished research in the following theoretical topics with the support of the present grant: 1) The evolution of mating types in a spatially explicit model 2) Research on problems of early evolution 3) The evolution of dispersal and mutualism 4) The dynamics of metapopulations in very noisy environments 5) The role of interference competition in the maintenance of the diversity of microbial communities 6) The strucure and the stability of food webs We have published 38 papers on these six topics with the number of the grant mentioned in the Acknowledgements of the papers. The cumulative impact factor of these publications is 113.86. We are planning to continue research in all the six topics.

Journal of Theoretical Biology, 2013

The existence of cooperation between species raises a fundamental problem for evolutionary theory... more The existence of cooperation between species raises a fundamental problem for evolutionary theory. Why provide costly services to another species if the feedback of this provision also happens to benefit intra-specific competitors that provide no service? Rewarding cooperators and punishing defectors can help maintain mutualism; this is not possible, however, when one can only respond to the collective action of one's partners, which is likely to be the case in many common symbioses. We show how the theory of public goods can explain the stability of mutualism when discrimination between cooperators and defectors is not possible: if two groups of individuals trade goods that are non-linear, increasing functions of the number of contributions, their mutualistic interaction is maintained by the exchange of these public goods, even when it is not possible to punish defectors, which can persist at relatively high frequencies. This provides a theoretical justification and testable predictions for the evolution of mutualism in the absence of discrimination mechanisms.

ABSTRACT Pályázatunk elsősorban a kooperáció eredetének számos aspektusát, továbbá a komunikációs... more ABSTRACT Pályázatunk elsősorban a kooperáció eredetének számos aspektusát, továbbá a komunikációs rendszerek őszinteségét fenntartó mechanizmusok tanulmányozta. Az elméleti munkák mellett e témakörben humán és állatkísérleteket is elindítottunk. Rámutattunk az olcsó vagy költségmentes kommunikáció őszinteségét fenntartó ökológiai tényezőkre. Megmutattuk például, hogy az emberi kooperáció és az őszinte kommunikáció evolúciója szoros kapcsolatban lehet, illetve állati társadalmakban a kommunikácó őszinteségét a kompetíció erőssége is befolyásolhatja. Vizsgáltuk az ember és a kutya kooperációjának kommunikációs sajátságait. Megmutattuk, hogy a préda-perdátor vagy gazda-parazita kölcsönhatások ismerete szükséges számos kooperatív viselkedés evolúciójának értelmezéséhez. Például a predációs nyomás okozhatja a prédák altruista viselkedését, vagy a kasztrációs parazitát éppen a mutualista társ jelenléte szabályozza. Számos tanulmányban az egyedek térbeli elhelyezkedésének és korlátozott mozgásának a kooperáció evolúciójára kifejtett hatását vizsgáltuk. Több olyan munkánk is született, ahol a humán kommunikáció illetve kooperáció sajátságait a többszintű szelekciós modellek segítségével értelmeztük. Sikerült kiépítsünk egy számítógépes labort, mellyel a jövőben s humán etológiai kísérleteket tudunk végezni. A kutatás legfontosabb eszközének számító evolúciós játékelméletben számos alapkutatás jellegű eredményünk is született, a sztochasztikus elmélet fejlesztésétől a többfajos elméletig. | Our project mainly focused on several aspects of the evolution of cooperation and of the mechanisms maintaining honesty in communicating systems. Beside theoretical works we started animal and human experiments as well. We reveal ecological backgrounds maintaining honesty of cheap or costless communication in numerous systems. It is shown for example that the origin of human cooperation and reliable information processing can be in close connection to each other, and that strength of competition modifies the level of honesty in animal communities. We studied the characteristics of communication in the case of human-dog cooperation. We have shown that characteristics of predator-prey or host-parasite interactions are required to explain evolution of cooperative behaviour in numerous cases. For example, predation load can cause altruistic predator defence among preys, or a mutualistic competitor can control castrating parasites. Several papers focused on the spatial aspects and limited migration of individuals on the evolution of cooperation. Other works emphasized that characteristics of human cooperation can be explained by multilevel selection. We set up a computer lab, which could be a basis of a series of human behavior experiment in the near future. We have significant purely theoretical results in the field of our primary mathematical method, that is of evolutionary game theory; from the development of stochastic theory to the multi-species theory.

Journal of Theoretical Biology, 1997

A simple metapopulation lattice model of two competing phenotypes is presented, where one phenoty... more A simple metapopulation lattice model of two competing phenotypes is presented, where one phenotype reacts more sensitively to overcrowding by migrating to neighboring local habitats. The sensitivity is formulated by means of a threshold density of the subpopulations, above which dispersal is triggered off. If this threshold density is not very far from the local carrying capacity, an increased mobility provides benefits on the metapopulation level. At a surprisingly small difference between migrational triggering thresholds, the phenotype of larger mobility (or lower threshold) squeezes out the less mobile one from the whole system in a wide parameter range. Evolutionary considerations give an optimal threshold level for our model metapopulation.

Chaos, 2002

We have analyzed the dynamics of metabolically coupled replicators in open chaotic flows. Replica... more We have analyzed the dynamics of metabolically coupled replicators in open chaotic flows. Replicators contribute to a common metabolism producing energy-rich monomers necessary for replication. The flow and the biological processes take place on a rectangular grid. There can be at most one molecule on each grid cell, and replication can occur only at localities where all the necessary replicators

Community Ecology, 2003

... However, only little experience has been accumulated on observer errors inherent in field est... more ... However, only little experience has been accumulated on observer errors inherent in field estima-tions (Sykes et al 1983, Gotfryd and Hansell 1985, Ken-nedy and Addison 1987, Lepš and Hadincová 1992, Klimeš et al 2001). ... I. Hahn 1 and I. Scheuring 1,2 ...

A generalized version of the N-person Volunteer's Dilemma Game (NVD) has been suggested recently ... more A generalized version of the N-person Volunteer's Dilemma Game (NVD) has been suggested recently for illustrating the problem of N-person social dilemmas. Using standard replicator dynamics it can be shown that coexistence of cooperators and defectors is typical in this model. However, the question of how a rare mutant cooperator could invade a population of defectors is still open.

Theoretical ecologists have observed chaotic behavior in population models for decades. However, ... more Theoretical ecologists have observed chaotic behavior in population models for decades. However, in the past few years, several studies indicate that complex dynamics, including chaos, become less probable in biologically more sophisticated models. For example, the inclusion of either sexual reproduction, population structure or dispersal generally increases stability. These results can explain the difference between the dynamical complexity of most theoretical models and the relative stability found within real time series.

Journal of theoretical biology, Jan 7, 2005

Laboratory experiments and numerical simulations have shown that the outcome of cyclic competitio... more Laboratory experiments and numerical simulations have shown that the outcome of cyclic competition is significantly affected by the spatial distribution of the competitors. Short-range interaction and limited dispersion allows for coexistence of competing species that cannot coexist in a well-mixed environment. In order to elucidate the mechanisms that destroy species diversity we study the intermediate situation of imperfect mixing, typical in aquatic media, in a model of cyclic competition between toxin producing, sensitive and resistant phenotypes. It is found, that chaotic mixing, by changing the character of the spatial distribution, induces coherent oscillations in the populations. The magnitude of the oscillations increases with the strength of mixing, leading to the extinction of some species beyond a critical mixing rate. When mixing is non-uniform in space, coexistence can be sustained at much stronger mixing by the formation of partially isolated regions, that prevent glo...