1
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Liu M, West SA, Wild G. The evolution of manipulative cheating. eLife 2022; 11:e80611. [PMID: 36193888 PMCID: PMC9633066 DOI: 10.7554/elife.80611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 10/03/2022] [Indexed: 01/07/2023] Open
Abstract
A social cheat is typically assumed to be an individual that does not perform a cooperative behaviour, or performs less of it, but can still exploit the cooperative behaviour of others. However, empirical data suggests that cheating can be more subtle, involving evolutionary arms races over the ability to both exploit and resist exploitation. These complications have not been captured by evolutionary theory, which lags behind empirical studies in this area. We bridge this gap with a mixture of game-theoretical models and individual-based simulations, examining what conditions favour more elaborate patterns of cheating. We found that as well as adjusting their own behaviour, individuals can be selected to manipulate the behaviour of others, which we term 'manipulative cheating'. Further, we found that manipulative cheating can lead to dynamic oscillations (arms races), between selfishness, manipulation, and suppression of manipulation. Our results can help explain both variation in the level of cheating, and genetic variation in the extent to which individuals can be exploited by cheats.
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Affiliation(s)
- Ming Liu
- Department of Biology, University of OxfordOxfordUnited Kingdom
| | | | - Geoff Wild
- Department of Mathematics, The University of Western OntarioLondonCanada
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2
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Rodrigues AMM, Estrela S, Brown SP. Community lifespan, niche expansion and the evolution of interspecific cooperation. J Evol Biol 2020; 34:352-363. [PMID: 33238064 DOI: 10.1111/jeb.13739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 09/25/2020] [Accepted: 11/06/2020] [Indexed: 11/29/2022]
Abstract
Microbes live in dense and diverse communities where they deploy many traits that promote the growth and survival of neighbouring species, all the while also competing for shared resources. Because microbial communities are highly dynamic, the costs and benefits of species interactions change over the growth cycle of a community. How mutualistic interactions evolve under such demographic and ecological conditions is still poorly understood. Here, we develop an eco-evolutionary model to explore how different forms of helping with distinct fitness effects (rate-enhancing and yield-enhancing) affect the multiple phases of community growth, and its consequences for the evolution of mutualisms. We specifically focus on a form of yield-enhancing trait in which cooperation augments the common pool of resources, termed niche expansion. We show that although mutualisms in which cooperation increases partners growth rate are generally favoured at early stages of community growth, niche expansion can evolve at later stages where densities are high. Further, we find that niche expansion can promote the evolution of reproductive restraint, in which a focal species adaptively reduces its own growth rate to increase the density of partner species. Our findings suggest that yield-enhancing mutualisms are more prevalent in stable habitats with a constant supply of resources, and where populations typically live at high densities. In general, our findings highlight the need to integrate different components of population growth in the analysis of mutualisms to understand the composition and function of microbial communities.
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Affiliation(s)
| | - Sylvie Estrela
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT, USA
| | - Sam P Brown
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.,Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA, USA
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3
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Gorter FA, Manhart M, Ackermann M. Understanding the evolution of interspecies interactions in microbial communities. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190256. [PMID: 32200743 DOI: 10.1098/rstb.2019.0256] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Microbial communities are complex multi-species assemblages that are characterized by a multitude of interspecies interactions, which can range from mutualism to competition. The overall sign and strength of interspecies interactions have important consequences for emergent community-level properties such as productivity and stability. It is not well understood how interspecies interactions change over evolutionary timescales. Here, we review the empirical evidence that evolution is an important driver of microbial community properties and dynamics on timescales that have traditionally been regarded as purely ecological. Next, we briefly discuss different modelling approaches to study evolution of communities, emphasizing the similarities and differences between evolutionary and ecological perspectives. We then propose a simple conceptual model for the evolution of interspecies interactions in communities. Specifically, we propose that to understand the evolution of interspecies interactions, it is important to distinguish between direct and indirect fitness effects of a mutation. We predict that in well-mixed environments, traits will be selected exclusively for their direct fitness effects, while in spatially structured environments, traits may also be selected for their indirect fitness effects. Selection of indirectly beneficial traits should result in an increase in interaction strength over time, while selection of directly beneficial traits should not have such a systematic effect. We tested our intuitions using a simple quantitative model and found support for our hypotheses. The next step will be to test these hypotheses experimentally and provide input for a more refined version of the model in turn, thus closing the scientific cycle of models and experiments. This article is part of the theme issue 'Conceptual challenges in microbial community ecology'.
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Affiliation(s)
- Florien A Gorter
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland.,Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
| | - Michael Manhart
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland.,Institute of Integrative Biology, Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland.,Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
| | - Martin Ackermann
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland.,Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
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4
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Patel M, Raymond B, Bonsall MB, West SA. Crystal toxins and the volunteer's dilemma in bacteria. J Evol Biol 2019; 32:310-319. [PMID: 30672052 PMCID: PMC6487926 DOI: 10.1111/jeb.13415] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 01/11/2019] [Accepted: 01/15/2019] [Indexed: 11/28/2022]
Abstract
The growth and virulence of the bacteria Bacillus thuringiensis depend on the production of Cry toxins, which are used to perforate the gut of its host. Successful invasion of the host relies on producing a threshold amount of toxin, after which there is no benefit from producing more toxin. Consequently, the production of Cry toxin appears to be a different type of social problem compared with the public goods scenarios that bacteria usually encounter. We show that selection for toxin production is a volunteer's dilemma. We make specific predictions that (a) selection for toxin production depends upon an interplay between the number of bacterial cells that each host ingests and the genetic relatedness between those cells; (b) cheats that do not produce toxin gain an advantage when at low frequencies, and at high bacterial density, allowing them to be maintained in a population alongside toxin‐producing cells. More generally, our results emphasize the diversity of the social games that bacteria play.
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Affiliation(s)
| | - Ben Raymond
- College of Life and Environmental Science, University of Exeter, Penryn, Cornwall, UK
| | | | - Stuart A West
- Department of Zoology, University of Oxford, Oxford, UK
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5
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dos Santos M, Ghoul M, West SA. Pleiotropy, cooperation, and the social evolution of genetic architecture. PLoS Biol 2018; 16:e2006671. [PMID: 30359363 PMCID: PMC6219813 DOI: 10.1371/journal.pbio.2006671] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 11/06/2018] [Accepted: 10/11/2018] [Indexed: 02/06/2023] Open
Abstract
Pleiotropy has been suggested as a novel mechanism for stabilising cooperation in bacteria and other microbes. The hypothesis is that linking cooperation with a trait that provides a personal (private) benefit can outweigh the cost of cooperation in situations when cooperation would not be favoured by mechanisms such as kin selection. We analysed the theoretical plausibility of this hypothesis, with analytical models and individual-based simulations. We found that (1) pleiotropy does not stabilise cooperation, unless the cooperative and private traits are linked via a genetic architecture that cannot evolve (mutational constraint); (2) if the genetic architecture is constrained in this way, then pleiotropy favours any type of trait and not especially cooperation; (3) if the genetic architecture can evolve, then pleiotropy does not favour cooperation; and (4) there are several alternative explanations for why traits may be linked, and causality can even be predicted in the opposite direction, with cooperation favouring pleiotropy. Our results suggest that pleiotropy could only explain cooperation under restrictive conditions and instead show how social evolution can shape the genetic architecture.
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Affiliation(s)
| | - Melanie Ghoul
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Stuart A. West
- Department of Zoology, University of Oxford, Oxford, United Kingdom
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6
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Bruce JB, Cooper GA, Chabas H, West SA, Griffin AS. Cheating and resistance to cheating in natural populations of the bacteriumPseudomonas fluorescens. Evolution 2017; 71:2484-2495. [DOI: 10.1111/evo.13328] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 07/14/2017] [Accepted: 08/08/2017] [Indexed: 12/11/2022]
Affiliation(s)
- John B. Bruce
- Department of Zoology; University of Oxford; Oxford UK
| | - Guy A. Cooper
- Department of Zoology; University of Oxford; Oxford UK
| | - Hélène Chabas
- CEFE UMR 5175, CNRS-Université de Montpellier; Université Paul-Valéry Montpellier; Montpellier Cedex 5 France
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7
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An age-dependent model to analyse the evolutionary stability of bacterial quorum sensing. J Theor Biol 2016; 405:104-15. [PMID: 26796220 DOI: 10.1016/j.jtbi.2015.12.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 12/07/2015] [Accepted: 12/16/2015] [Indexed: 01/13/2023]
Abstract
Bacterial communication is enabled through the collective release and sensing of signalling molecules in a process called quorum sensing. Cooperative processes can easily be destabilized by the appearance of cheaters, who contribute little or nothing at all to the production of common goods. This especially applies for planktonic cultures. In this study, we analyse the dynamics of bacterial quorum sensing and its evolutionary stability under two levels of cooperation, namely signal and enzyme production. The model accounts for mutation rates and switches between planktonic and biofilm state of growth. We present a mathematical approach to model these dynamics using age-dependent colony models. We explore the conditions under which cooperation is stable and find that spatial structuring can lead to long-term scenarios such as coexistence or bistability, depending on the non-linear combination of different parameters like death rates and production costs.
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8
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Hummert S, Bohl K, Basanta D, Deutsch A, Werner S, Theissen G, Schroeter A, Schuster S. Evolutionary game theory: cells as players. MOLECULAR BIOSYSTEMS 2015; 10:3044-65. [PMID: 25270362 DOI: 10.1039/c3mb70602h] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In two papers we review game theory applications in biology below the level of cognitive living beings. It can be seen that evolution and natural selection replace the rationality of the actors appropriately. Even in these micro worlds, competing situations and cooperative relationships can be found and modeled by evolutionary game theory. Also those units of the lowest levels of life show different strategies for different environmental situations or different partners. We give a wide overview of evolutionary game theory applications to microscopic units. In this first review situations on the cellular level are tackled. In particular metabolic problems are discussed, such as ATP-producing pathways, secretion of public goods and cross-feeding. Further topics are cyclic competition among more than two partners, intra- and inter-cellular signalling, the struggle between pathogens and the immune system, and the interactions of cancer cells. Moreover, we introduce the theoretical basics to encourage scientists to investigate problems in cell biology and molecular biology by evolutionary game theory.
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Affiliation(s)
- Sabine Hummert
- Fachhochschule Schmalkalden, Faculty of Electrical Engineering, Blechhammer, 98574 Schmalkalden, Germany
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9
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Abstract
Microbes produce many compounds that are costly to a focal cell but promote the survival and reproduction of neighboring cells. This observation has led to the suggestion that microbial strains and species will commonly cooperate by exchanging compounds. Here, we examine this idea with an ecoevolutionary model where microbes make multiple secretions, which can be exchanged among genotypes. We show that cooperation between genotypes only evolves under specific demographic regimes characterized by intermediate genetic mixing. The key constraint on cooperative exchanges is a loss of autonomy: strains become reliant on complementary genotypes that may not be reliably encountered. Moreover, the form of cooperation that we observe arises through mutual exploitation that is related to cheating and "Black Queen" evolution for a single secretion. A major corollary is that the evolution of cooperative exchanges reduces community productivity relative to an autonomous strain that makes everything it needs. This prediction finds support in recent work from synthetic communities. Overall, our work suggests that natural selection will often limit cooperative exchanges in microbial communities and that, when exchanges do occur, they can be an inefficient solution to group living.
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10
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Frank SA. Microbial metabolism: optimal control of uptake versus synthesis. PeerJ 2014; 2:e267. [PMID: 24795846 PMCID: PMC3940620 DOI: 10.7717/peerj.267] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 01/20/2014] [Indexed: 11/20/2022] Open
Abstract
Microbes require several complex organic molecules for growth. A species may obtain a required factor by taking up molecules released by other species or by synthesizing the molecule. The patterns of uptake and synthesis set a flow of resources through the multiple species that create a microbial community. This article analyzes a simple mathematical model of the tradeoff between uptake and synthesis. Key factors include the influx rate from external sources relative to the outflux rate, the rate of internal decay within cells, and the cost of synthesis. Aspects of demography also matter, such as cellular birth and death rates, the expected time course of a local resource flow, and the associated lifespan of the local population. Spatial patterns of genetic variability and differentiation between populations may also strongly influence the evolution of metabolic regulatory controls of individual species and thus the structuring of microbial communities. The widespread use of optimality approaches in recent work on microbial metabolism has ignored demography and genetic structure.
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Affiliation(s)
- Steven A Frank
- Department of Ecology and Evolutionary Biology, University of California , Irvine , CA , USA
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11
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Abstract
Mutant lineages may cause cancer-like overgrowths in microbial populations. Theory predicts that microbial regulatory controls may be designed to limit the origin and competitive potential of rogue lineages. A new study shows how a Salmonella species protects itself against overgrowths.
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12
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Ghoul M, Griffin AS, West SA. Toward an evolutionary definition of cheating. Evolution 2013; 68:318-31. [PMID: 24131102 DOI: 10.1111/evo.12266] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 08/27/2013] [Indexed: 12/17/2022]
Abstract
The term "cheating" is used in the evolutionary and ecological literature to describe a wide range of exploitative or deceitful traits. Although many find this a useful short hand, others have suggested that it implies cognitive intent in a misleading way, and is used inconsistently. We provide a formal justification of the use of the term "cheat" from the perspective of an individual as a maximizing agent. We provide a definition for cheating that can be applied widely, and show that cheats can be broadly classified on the basis of four distinctions: (i) whether cooperation is an option; (ii) whether deception is involved; (iii) whether members of the same or different species are cheated; and (iv) whether the cheat is facultative or obligate. Our formal definition and classification provide a framework that allow us to resolve and clarify a number of issues, regarding the detection and evolutionary consequences of cheating, as well as illuminating common principles and similarities in the underlying selection pressures.
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Affiliation(s)
- Melanie Ghoul
- Department of Zoology, Oxford University, Oxford, OX1 3PS, United Kingdom.
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13
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Taylor TB, Rodrigues AMM, Gardner A, Buckling A. The social evolution of dispersal with public goods cooperation. J Evol Biol 2013; 26:2644-53. [DOI: 10.1111/jeb.12259] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 08/27/2013] [Accepted: 09/02/2013] [Indexed: 01/18/2023]
Affiliation(s)
- T. B. Taylor
- Department of Zoology; University of Oxford; Oxford UK
- School of Biological Sciences; University of Reading; Reading UK
| | | | - A. Gardner
- Department of Zoology; University of Oxford; Oxford UK
- Balliol College, University of Oxford; Oxford UK
- School of Biology; University of St Andrews; St Andrews UK
| | - A. Buckling
- Department of Zoology; University of Oxford; Oxford UK
- Biosciences; University of Exeter; Penryn UK
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14
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Van Dyken JD, Wade MJ. Detecting the molecular signature of social conflict: theory and a test with bacterial quorum sensing genes. Am Nat 2012; 179:436-50. [PMID: 22437174 DOI: 10.1086/664609] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Extending social evolution theory to the molecular level opens the door to an unparalleled abundance of data and statistical tools for testing alternative hypotheses about the long-term evolutionary dynamics of cooperation and conflict. To this end, we take a collection of known sociality genes (bacterial quorum sensing [QS] genes), model their evolution in terms of patterns that are detectable using gene sequence data, and then test model predictions using available genetic data sets. Specifically, we test two alternative hypotheses of social conflict: (1) the "adaptive" hypothesis that cheaters are maintained in natural populations by frequency-dependent balancing selection as an evolutionarily stable strategy and (2) the "evolutionary null" hypothesis that cheaters are opposed by purifying kin selection yet exist transiently because of their recurrent introduction into populations by mutation (i.e., kin selection-mutation balance). We find that QS genes have elevated within- and among-species sequence variation, nonsignificant signatures of natural selection, and putatively small effect sizes of mutant alleles, all patterns predicted by our evolutionary null model but not by the stable cheater hypothesis. These empirical findings support our theoretical prediction that QS genes experience relaxed selection due to nonclonality of social groups, conditional expression, and the individual-level advantage enjoyed by cheaters. Furthermore, cheaters are evolutionarily transient, persisting in populations because of their recurrent introduction by mutation and not because they enjoy a frequency-dependent fitness advantage.
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Affiliation(s)
- J David Van Dyken
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
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15
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Bonsall M, Charlesworth B. Genetics and the causes of evolution: 150 years of progress since Darwin. Philos Trans R Soc Lond B Biol Sci 2010; 365:2427-9. [PMID: 20643731 DOI: 10.1098/rstb.2010.0109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Michael Bonsall
- Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
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