1
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Hesse E, O’Brien S. Ecological dependencies and the illusion of cooperation in microbial communities. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001442. [PMID: 38385784 PMCID: PMC10924460 DOI: 10.1099/mic.0.001442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 02/09/2024] [Indexed: 02/23/2024]
Abstract
Ecological dependencies - where organisms rely on other organisms for survival - are a ubiquitous feature of life on earth. Multicellular hosts rely on symbionts to provide essential vitamins and amino acids. Legume plants similarly rely on nitrogen-fixing rhizobia to convert atmospheric nitrogen to ammonia. In some cases, dependencies can arise via loss-of-function mutations that allow one partner to benefit from the actions of another. It is common in microbiology to label ecological dependencies between species as cooperation - making it necessary to invoke cooperation-specific frameworks to explain the phenomenon. However, in many cases, such traits are not (at least initially) cooperative, because they are not selected for because of the benefits they confer on a partner species. In contrast, dependencies in microbial communities may originate from fitness benefits gained from genomic-streamlining (i.e. Black Queen Dynamics). Here, we outline how the Black Queen Hypothesis predicts the formation of metabolic dependencies via loss-of-function mutations in microbial communities, without needing to invoke any cooperation-specific explanations. Furthermore we outline how the Black Queen Hypothesis can act as a blueprint for true cooperation as well as discuss key outstanding questions in the field. The nature of interactions in microbial communities can predict the ability of natural communities to withstand and recover from disturbances. Hence, it is vital to gain a deeper understanding of the factors driving these dynamic interactions over evolutionary time.
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Affiliation(s)
- Elze Hesse
- College of Life and Environmental Science, University of Exeter, Penryn, Cornwall, TR10 9FE, UK
| | - Siobhán O’Brien
- Moyne Institute of Preventive Medicine, Department of Microbiology, School of Genetics and Microbiology, Trinity College Dublin, Dublin 2, Ireland
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2
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Luo ZH, Li Q, Chen N, Tang LY, Liao B, Yang TT, Huang LN. Genome-resolved metagenomics reveals depth-related patterns of microbial community structure and functions in a highly stratified, AMD overlaying mine tailings. JOURNAL OF HAZARDOUS MATERIALS 2023; 447:130774. [PMID: 36641850 DOI: 10.1016/j.jhazmat.2023.130774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 01/04/2023] [Accepted: 01/09/2023] [Indexed: 06/17/2023]
Abstract
Acid mine drainage (AMD) is a worldwide environmental problem, yet bioremediation is hampered by a limited knowledge of the reductive microbial processes in the AMD ecosystem. Here, we generate extensive metagenome and geochemical datasets to investigate how microbial populations and metabolic capacities driving major element cycles are structured in a highly stratified, AMD overlaying tailings environment. The results demonstrated an explicit depth-dependent differentiation of microbial community composition and function profiles between the surface and deeper tailings layers, paralleling the dramatic shifts in major physical and geochemical properties. Specifically, key genes involved in sulfur and iron oxidation were significantly enriched in the surface tailings, whereas those associated with reductive nitrogen, sulfur, and iron processes were enriched in the deeper layers. Genome-resolved metagenomics retrieved 406 intermediate or high-quality genomes spanning 26 phyla, including major new groups (e.g., Patescibacteria and DPANN). Metabolic models involving nitrogen, sulfur, iron, and carbon cycles were proposed based on the functional potentials of the abundant microbial genomes, emphasizing syntrophy and the importance of lesser-known taxa in the degradation of complex carbon compounds. These results have implications for in situ AMD bioremediation.
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Affiliation(s)
- Zhen-Hao Luo
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Qi Li
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Nan Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Ling-Yun Tang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Bin Liao
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Tao-Tao Yang
- Guangdong Heavy Metal Mine Ecological Restoration Engineering Technology Research Center, Shaoguan, China
| | - Li-Nan Huang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
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3
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Iron acquisition strategies in pseudomonads: mechanisms, ecology, and evolution. Biometals 2022:10.1007/s10534-022-00480-8. [PMID: 36508064 PMCID: PMC10393863 DOI: 10.1007/s10534-022-00480-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
AbstractIron is important for bacterial growth and survival, as it is a common co-factor in essential enzymes. Although iron is very abundant in the earth crust, its bioavailability is low in most habitats because ferric iron is largely insoluble under aerobic conditions and at neutral pH. Consequently, bacteria have evolved a plethora of mechanisms to solubilize and acquire iron from environmental and host stocks. In this review, I focus on Pseudomonas spp. and first present the main iron uptake mechanisms of this taxa, which involve the direct uptake of ferrous iron via importers, the production of iron-chelating siderophores, the exploitation of siderophores produced by other microbial species, and the use of iron-chelating compounds produced by plants and animals. In the second part of this review, I elaborate on how these mechanisms affect interactions between bacteria in microbial communities, and between bacteria and their hosts. This is important because Pseudomonas spp. live in diverse communities and certain iron-uptake strategies might have evolved not only to acquire this essential nutrient, but also to gain relative advantages over competitors in the race for iron. Thus, an integrative understanding of the mechanisms of iron acquisition and the eco-evolutionary dynamics they drive at the community level might prove most useful to understand why Pseudomonas spp., in particular, and many other bacterial species, in general, have evolved such diverse iron uptake repertoires.
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4
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Gangan MS, Vasconcelos MM, Mitra U, Câmara O, Boedicker JQ. Intertemporal trade-off between population growth rate and carrying capacity during public good production. iScience 2022; 25:104117. [PMID: 35391831 PMCID: PMC8980746 DOI: 10.1016/j.isci.2022.104117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 01/14/2022] [Accepted: 03/16/2022] [Indexed: 11/19/2022] Open
Abstract
Public goods are biomolecules that benefit cellular populations, such as by providing access to previously unutilized resources. Public good production is energetically costly. To reduce this cost, populations control public good biosynthesis, for example using density-dependent regulation accomplished by quorum sensing. Fitness costs and benefits of public good production must be balanced, similar to optimal investment decisions used in economics. We explore the regulation of a public good that increases the carrying capacity, through experimental measurements of growth in Escherichia coli and analysis using a modified logistic growth model. The timing of public good production showed a sharply peaked optimum in population fitness. The cell density associated with maximum public good benefits was determined by the trade-off between the cost of public good production, in terms of reduced growth rate, and benefits received from public goods, in the form of increased carrying capacity. Public good production creates trade-off between growth rate and carrying capacity Cell density-dependent regulation times the production to optimize this trade-off At this time, benefits of public good are maximum and received instantaneously
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Affiliation(s)
- Manasi S. Gangan
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA, USA
| | - Marcos M. Vasconcelos
- Commonweath Cyber-Initiative and Bradley Department of Electrical Engineering, Virginia Polytechnic Institute and State University, Arlington, VA, USA
| | - Urbashi Mitra
- Ming Hsieh Department of Electrical & Computer Engineering, Department of Computer Science, University of Southern California, Los Angeles, CA, USA
| | - Odilon Câmara
- USC Marshall School of Business, University of Southern California, Los Angeles, CA, USA
| | - James Q. Boedicker
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA, USA
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
- Corresponding author
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5
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Cummins EA, Hall RJ, McInerney JO, McNally A. Prokaryote pangenomes are dynamic entities. Curr Opin Microbiol 2022; 66:73-78. [PMID: 35104691 DOI: 10.1016/j.mib.2022.01.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 11/24/2022]
Abstract
Prokaryote pangenomes are influenced heavily by environmental factors and the opportunity for gene gain and loss events. As the field of pangenome analysis has expanded, so has the need to fully understand the complexity of how eco-evolutionary dynamics shape pangenomes. Here, we describe current models of pangenome evolution and discuss their suitability and accuracy. We suggest that pangenomes are dynamic entities under constant flux, highlighting the influence of two-way interactions between pangenome and environment. New classifications of core and accessory genes are also considered, underscoring the need for continuous evaluation of nomenclature in a fast-moving field. We conclude that future models of pangenome evolution should incorporate eco-evolutionary dynamics to fully encompass their dynamic, changeable nature.
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Affiliation(s)
- Elizabeth A Cummins
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Rebecca J Hall
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
| | - James O McInerney
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Alan McNally
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
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6
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Figueiredo ART, Wagner A, Kümmerli R. Ecology drives the evolution of diverse social strategies in Pseudomonas aeruginosa. Mol Ecol 2021; 30:5214-5228. [PMID: 34390514 PMCID: PMC9291133 DOI: 10.1111/mec.16119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 06/03/2021] [Accepted: 07/28/2021] [Indexed: 11/27/2022]
Abstract
Bacteria often cooperate by secreting molecules that can be shared as public goods between cells. Because the production of public goods is subject to cheating by mutants that exploit the good without contributing to it, there has been great interest in elucidating the evolutionary forces that maintain cooperation. However, little is known about how bacterial cooperation evolves under conditions where cheating is unlikely to be of importance. Here we use experimental evolution to follow changes in the production of a model public good, the iron‐scavenging siderophore pyoverdine, of the bacterium Pseudomonas aeruginosa. After 1200 generations of evolution in nine different environments, we observed that cheaters only reached high frequency in liquid medium with low iron availability. Conversely, when adding iron to reduce the cost of producing pyoverdine, we observed selection for pyoverdine hyperproducers. Similarly, hyperproducers also spread in populations evolved in highly viscous media, where relatedness between interacting individuals is increased. Whole‐genome sequencing of evolved clones revealed that hyperproduction is associated with mutations involving genes encoding quorum‐sensing communication systems, while cheater clones had mutations in the iron‐starvation sigma factor or in pyoverdine biosynthesis genes. Our findings demonstrate that bacterial social traits can evolve rapidly in divergent directions, with particularly strong selection for increased levels of cooperation occurring in environments where individual dispersal is reduced, as predicted by social evolution theory. Moreover, we establish a regulatory link between pyoverdine production and quorum‐sensing, showing that increased cooperation with respect to one trait (pyoverdine) can be associated with the loss (quorum‐sensing) of another social trait.
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Affiliation(s)
- Alexandre R T Figueiredo
- Department of Quantitative Biomedicine, University of Zurich, 8057, Zurich, Switzerland.,Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057, Zurich, Switzerland.,Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Andreas Wagner
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057, Zurich, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland.,The Santa Fe Institute, Santa Fe, New Mexico, United States of America
| | - Rolf Kümmerli
- Department of Quantitative Biomedicine, University of Zurich, 8057, Zurich, Switzerland.,Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
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7
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Gitschlag BL, Tate AT, Patel MR. Nutrient status shapes selfish mitochondrial genome dynamics across different levels of selection. eLife 2020; 9:56686. [PMID: 32959778 PMCID: PMC7508553 DOI: 10.7554/elife.56686] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 08/17/2020] [Indexed: 12/23/2022] Open
Abstract
Cooperation and cheating are widespread evolutionary strategies. While cheating confers an advantage to individual entities within a group, competition between groups favors cooperation. Selfish or cheater mitochondrial DNA (mtDNA) proliferates within hosts while being selected against at the level of host fitness. How does environment shape cheater dynamics across different selection levels? Focusing on food availability, we address this question using heteroplasmic Caenorhabditis elegans. We find that the proliferation of selfish mtDNA within hosts depends on nutrient status stimulating mtDNA biogenesis in the developing germline. Interestingly, mtDNA biogenesis is not sufficient for this proliferation, which also requires the stress-response transcription factor FoxO/DAF-16. At the level of host fitness, FoxO/DAF-16 also prevents food scarcity from accelerating the selection against selfish mtDNA. This suggests that the ability to cope with nutrient stress can promote host tolerance of cheaters. Our study delineates environmental effects on selfish mtDNA dynamics at different levels of selection.
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Affiliation(s)
- Bryan L Gitschlag
- Department of Biological Sciences, Vanderbilt University, Nashville, United States
| | - Ann T Tate
- Department of Biological Sciences, Vanderbilt University, Nashville, United States
| | - Maulik R Patel
- Department of Biological Sciences, Vanderbilt University, Nashville, United States.,Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States.,Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, United States
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8
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Leventhal GE, Ackermann M, Schiessl KT. Why microbes secrete molecules to modify their environment: the case of iron-chelating siderophores. J R Soc Interface 2020; 16:20180674. [PMID: 30958157 DOI: 10.1098/rsif.2018.0674] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Many microorganisms secrete molecules that interact with resources outside of the cell. This includes, for example, enzymes that degrade polymers like chitin, and chelators that bind trace metals like iron. In contrast to direct uptake via the cell surface, such release strategies entail the risk of losing the secreted molecules to environmental sinks, including 'cheating' genotypes. Nevertheless, such secretion strategies are widespread, even in the well-mixed marine environment. Here, we investigate the benefits of a release strategy whose efficiency has frequently been questioned: iron uptake in the ocean by secretion of iron chelators called siderophores. We asked the question whether the release itself is essential for the function of siderophores, which could explain why this risky release strategy is widespread. We developed a reaction-diffusion model to determine the impact of siderophore release on iron uptake from the predominant iron sources in marine environments, colloidal or particulate iron, formed due to poor iron solubility. We found that release of siderophores is essential to accelerate iron uptake, as secreted siderophores transform slowly diffusing large iron particles to small, quickly diffusing iron-siderophore complexes. In addition, we found that cells can synergistically share their siderophores, depending on their distance and the size of the iron sources. Our study helps understand why release of siderophores is so widespread: even though a large fraction of siderophores is lost, the solubilization of iron through secreted siderophores can efficiently increase iron uptake, especially if siderophores are produced cooperatively by several cells. Overall, resource uptake mediated via release of molecules transforming their substrate could be essential to overcome diffusion limitation specifically in the cases of large, aggregated resources. In addition, we find that including the reaction of the released molecule with the substrate can impact the result of cooperative and competitive interactions, making our model also relevant for release-based uptake of other substrates.
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Affiliation(s)
- Gabriel E Leventhal
- 1 Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (MIT) , Cambridge, MA , USA.,2 Institute of Integrative Biology, Swiss Federal Institute of Technology Zurich (ETH Zurich) , Zurich , Switzerland
| | - Martin Ackermann
- 3 Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology Zurich (ETH Zurich) , Zurich , Switzerland.,4 Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag) , Dübendorf , Switzerland
| | - Konstanze T Schiessl
- 3 Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology Zurich (ETH Zurich) , Zurich , Switzerland.,4 Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag) , Dübendorf , Switzerland.,5 Department of Biological Sciences, Columbia University , New York, NY , USA
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9
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Stilwell P, O'Brien S, Hesse E, Lowe C, Gardner A, Buckling A. Resource heterogeneity and the evolution of public goods cooperation. Evol Lett 2020; 4:155-163. [PMID: 32313690 PMCID: PMC7156101 DOI: 10.1002/evl3.158] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 01/12/2020] [Accepted: 01/13/2020] [Indexed: 11/26/2022] Open
Abstract
Heterogeneity in resources is a ubiquitous feature of natural landscapes affecting many aspects of biology. However, the effect of environmental heterogeneity on the evolution of cooperation has been less well studied. Here, using a mixture of theory and experiments measuring siderophore production by the bacterium Pseudomonas aeruginosa as a model for public goods based cooperation, we explore the effect of heterogeneity in resource availability. We show that cooperation in metapopulations that were spatially heterogeneous in terms of resources can be maintained at a higher level than in homogeneous metapopulations of the same average resource value. The results can be explained by a positive covariance between fitness of cooperators, population size, and local resource availability, which allowed cooperators to have a disproportionate advantage within the heterogeneous metapopulations. These results suggest that natural environmental variation may help to maintain cooperation.
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Affiliation(s)
- Peter Stilwell
- Department of Biosciences University of Exeter Penryn TR10 9FE United Kingdom
| | - Siobhan O'Brien
- Institute of Integrative Biology University of Liverpool Liverpool L69 7ZB United Kingdom
| | - Elze Hesse
- Department of Biosciences University of Exeter Penryn TR10 9FE United Kingdom
| | - Chris Lowe
- Department of Biosciences University of Exeter Penryn TR10 9FE United Kingdom
| | - Andy Gardner
- School of Biology University of St Andrews St Andrews KY16 9TH United Kingdom
| | - Angus Buckling
- Department of Biosciences University of Exeter Penryn TR10 9FE United Kingdom
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10
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Wang X, Zheng Z, Fu F. Steering eco-evolutionary game dynamics with manifold control. Proc Math Phys Eng Sci 2020; 476:20190643. [PMID: 32082066 PMCID: PMC7016546 DOI: 10.1098/rspa.2019.0643] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 11/18/2019] [Indexed: 01/06/2023] Open
Abstract
Feedback loops between population dynamics of individuals and their ecological environment are ubiquitously found in nature and have shown profound effects on the resulting eco-evolutionary dynamics. By incorporating linear environmental feedback law into the replicator dynamics of two-player games, recent theoretical studies have shed light on understanding the oscillating dynamics of the social dilemma. However, the detailed effects of more general nonlinear feedback loops in multi-player games, which are more common especially in microbial systems, remain unclear. Here, we focus on ecological public goods games with environmental feedbacks driven by a nonlinear selection gradient. Unlike previous models, multiple segments of stable and unstable equilibrium manifolds can emerge from the population dynamical systems. We find that a larger relative asymmetrical feedback speed for group interactions centred on cooperators not only accelerates the convergence of stable manifolds but also increases the attraction basin of these stable manifolds. Furthermore, our work offers an innovative manifold control approach: by designing appropriate switching control laws, we are able to steer the eco-evolutionary dynamics to any desired population state. Our mathematical framework is an important generalization and complement to coevolutionary game dynamics, and also fills the theoretical gap in guiding the widespread problem of population state control in microbial experiments.
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Affiliation(s)
- Xin Wang
- LMIB, NLSDE, BDBC, PCL and School of Mathematical Sciences, Beihang University, Beijing 100191, People’s Republic of China
- Department of Mathematics, Dartmouth College, Hanover, NH 03755, USA
| | - Zhiming Zheng
- LMIB, NLSDE, BDBC, PCL and School of Mathematical Sciences, Beihang University, Beijing 100191, People’s Republic of China
| | - Feng Fu
- Department of Mathematics, Dartmouth College, Hanover, NH 03755, USA
- Department of Biomedical Data Science, Dartmouth College, Lebanon, NH 03756, USA
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11
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Bergk Pinto B, Maccario L, Dommergue A, Vogel TM, Larose C. Do Organic Substrates Drive Microbial Community Interactions in Arctic Snow? Front Microbiol 2019; 10:2492. [PMID: 31749784 PMCID: PMC6842950 DOI: 10.3389/fmicb.2019.02492] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Accepted: 10/16/2019] [Indexed: 12/19/2022] Open
Abstract
The effect of nutrients on microbial interactions, including competition and collaboration, has mainly been studied in laboratories, but their potential application to complex ecosystems is unknown. Here, we examined the effect of changes in organic acids among other parameters on snow microbial communities in situ over 2 months. We compared snow bacterial communities from a low organic acid content period to that from a higher organic acid period. We hypothesized that an increase in organic acids would shift the dominant microbial interaction from collaboration to competition. To evaluate microbial interactions, we built taxonomic co-variance networks from OTUs obtained from 16S rRNA gene sequencing. In addition, we tracked marker genes of microbial cooperation (plasmid backbone genes) and competition (antibiotic resistance genes) across both sampling periods in metagenomes and metatranscriptomes. Our results showed a decrease in the average connectivity of the network during late spring compared to the early spring that we interpreted as a decrease of cooperation. This observation was strengthened by the significantly more abundant plasmid backbone genes in the metagenomes from the early spring. The modularity of the network from the late spring was also found to be higher than the one from the early spring, which is another possible indicator of increased competition. Antibiotic resistance genes were significantly more abundant in the late spring metagenomes. In addition, antibiotic resistance genes were also positively correlated to the organic acid concentration of the snow across both seasons. Snow organic acid content might be responsible for this change in bacterial interactions in the Arctic snow community.
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Affiliation(s)
- Benoît Bergk Pinto
- Environmental Microbial Genomics, Laboratoire Ampère, École Centrale de Lyon, UMR CNRS 5005, Université de Lyon, Lyon, France
| | - Lorrie Maccario
- Environmental Microbial Genomics, Laboratoire Ampère, École Centrale de Lyon, UMR CNRS 5005, Université de Lyon, Lyon, France
| | - Aurélien Dommergue
- Univ Grenoble Alpes, CNRS, IRD, Grenoble INP, Institut des Géosciences de l'Environnement, Grenoble, France
| | - Timothy M Vogel
- Environmental Microbial Genomics, Laboratoire Ampère, École Centrale de Lyon, UMR CNRS 5005, Université de Lyon, Lyon, France
| | - Catherine Larose
- Environmental Microbial Genomics, Laboratoire Ampère, École Centrale de Lyon, UMR CNRS 5005, Université de Lyon, Lyon, France
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12
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Smith RP, Doiron A, Muzquiz R, Fortoul MC, Haas M, Abraham T, Quinn RJ, Barraza I, Chowdhury K, Nemzer LR. The public and private benefit of an impure public good determines the sensitivity of bacteria to population collapse in a snowdrift game. Environ Microbiol 2019; 21:4330-4342. [DOI: 10.1111/1462-2920.14796] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/28/2019] [Accepted: 08/29/2019] [Indexed: 01/05/2023]
Affiliation(s)
- Robert P. Smith
- Department of Biological Sciences Halmos College of Natural Sciences and Oceanography, Nova Southeastern University Fort Lauderdale FL USA
| | - Aimee Doiron
- Department of Biological Sciences Halmos College of Natural Sciences and Oceanography, Nova Southeastern University Fort Lauderdale FL USA
| | - Rodrigo Muzquiz
- Department of Biological Sciences Halmos College of Natural Sciences and Oceanography, Nova Southeastern University Fort Lauderdale FL USA
| | - Marla C. Fortoul
- Department of Biological Sciences Halmos College of Natural Sciences and Oceanography, Nova Southeastern University Fort Lauderdale FL USA
| | - Meghan Haas
- Department of Biological Sciences Halmos College of Natural Sciences and Oceanography, Nova Southeastern University Fort Lauderdale FL USA
| | - Tom Abraham
- Department of Biological Sciences Halmos College of Natural Sciences and Oceanography, Nova Southeastern University Fort Lauderdale FL USA
| | - Rebecca J. Quinn
- Department of Biological Sciences Halmos College of Natural Sciences and Oceanography, Nova Southeastern University Fort Lauderdale FL USA
| | - Ivana Barraza
- Department of Biological Sciences Halmos College of Natural Sciences and Oceanography, Nova Southeastern University Fort Lauderdale FL USA
| | - Khadija Chowdhury
- Department of Biological Sciences Halmos College of Natural Sciences and Oceanography, Nova Southeastern University Fort Lauderdale FL USA
| | - Louis R. Nemzer
- Department of Chemistry and Physics Halmos College of Natural Sciences and Oceanography, Nova Southeastern University Fort Lauderdale FL USA
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13
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Zhao K, Li J, Huang T, Yuan Y, Lin J, Yue B, Wang X, Chu Y. Coexistence of Microbial Species in Structured Communities by Forming a Hawk-Dove Game Like Interactive Relationship. Front Microbiol 2019; 10:807. [PMID: 31057514 PMCID: PMC6477097 DOI: 10.3389/fmicb.2019.00807] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 03/29/2019] [Indexed: 11/13/2022] Open
Abstract
Microorganisms evolve kinds of elaborate interaction models that can form relatively stable communities in a wide range of ecosystems. It is recognized that the spatial genetic structure of microbes in surface-attached environments lays a good foundation for the persistence of polymicrobial communities in adverse conditions. However, the interacting dynamics of microbes in facilitating the formation and stabilization of community structure still remains elusive. In this study, we identify a hawk-dove game like interspecific relationship between the two Gram-negative opportunistic pathogens Pseudomonas aeruginosa and Klebsiella pneumoniae, which naturally coexist in insect gut and can cocolonize human tissues. Specifically, although P. aeruginosa had significant competitive advantage over cocultured K. pneumoniae on solid medium with rich nutrient factors, K. pneumoniae could resist the suppression of P. aeruginosa by enhancing the expression of membrane transporters induced by the extracellular metabolites of P. aeruginosa. By contrast, under the condition that K. pneumoniae had a growth advantage but P. aeruginosa met a metabolic burden in producing quorum-sensing-controlled extracellular products, the frequency of K. pneumoniae would be slightly higher than P. aeruginosa during the coexistence because K. pneumoniae was also capable of exploiting the extracellular metabolite from P. aeruginosa. In addition, P. aeruginosa quorum-sensing variant could reap benefits from K. pneumoniae in turn and reach a relatively stable two species equilibrium. These findings provide an explanation for the formation and maintenance of polymicrobial communities in different spatially structured environments, and thus may contribute to understanding the complex interspecific interactions of microbes in local communities and shed new light on the development of social microbiology.
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Affiliation(s)
- Kelei Zhao
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China
| | - Jing Li
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China
| | - Ting Huang
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China
| | - Yang Yuan
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China
| | - Jiafu Lin
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China
| | - Bisong Yue
- Key Laboratory of Bio-Resources and Eco-Environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu, China
| | - Xinrong Wang
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China
| | - Yiwen Chu
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, China
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14
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Schiessl KT, Ross-Gillespie A, Cornforth DM, Weigert M, Bigosch C, Brown SP, Ackermann M, Kümmerli R. Individual- versus group-optimality in the production of secreted bacterial compounds. Evolution 2019; 73:675-688. [PMID: 30793292 DOI: 10.1111/evo.13701] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 02/01/2019] [Indexed: 01/10/2023]
Abstract
How unicellular organisms optimize the production of compounds is a fundamental biological question. While it is typically thought that production is optimized at the individual-cell level, secreted compounds could also allow for optimization at the group level, leading to a division of labor where a subset of cells produces and shares the compound with everyone. Using mathematical modeling, we show that the evolution of such division of labor depends on the cost function of compound production. Specifically, for any trait with saturating benefits, linear costs promote the evolution of uniform production levels across cells. Conversely, production costs that diminish with higher output levels favor the evolution of specialization-especially when compound shareability is high. When experimentally testing these predictions with pyoverdine, a secreted iron-scavenging compound produced by Pseudomonas aeruginosa, we found linear costs and, consistent with our model, detected uniform pyoverdine production levels across cells. We conclude that for shared compounds with saturating benefits, the evolution of division of labor is facilitated by a diminishing cost function. More generally, we note that shifts in the level of selection from individuals to groups do not solely require cooperation, but critically depend on mechanistic factors, including the distribution of compound synthesis costs.
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Affiliation(s)
- Konstanze T Schiessl
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, 8600, Switzerland.,Department of Environmental Systems Science, Swiss Federal Institute of Technology (ETH Zurich), Zürich, 8092, Switzerland.,Current Address: Department of Biological Sciences, Columbia University, 1212 Amsterdam Avenue, New York, 10027, New York
| | - Adin Ross-Gillespie
- Department of Plant and Microbial Biology, University of Zürich, Zürich, 8057, Switzerland
| | - Daniel M Cornforth
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, 30332, Georgia
| | - Michael Weigert
- Department of Plant and Microbial Biology, University of Zürich, Zürich, 8057, Switzerland
| | - Colette Bigosch
- Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH Zurich), Zürich, 8092, Switzerland
| | - Sam P Brown
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, 30332, Georgia
| | - Martin Ackermann
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, 8600, Switzerland.,Department of Environmental Systems Science, Swiss Federal Institute of Technology (ETH Zurich), Zürich, 8092, Switzerland
| | - Rolf Kümmerli
- Department of Plant and Microbial Biology, University of Zürich, Zürich, 8057, Switzerland.,Department of Quantitative Biomedicine, University of Zürich, Zürich, 8057, Switzerland
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15
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Butaitė E, Kramer J, Wyder S, Kümmerli R. Environmental determinants of pyoverdine production, exploitation and competition in natural Pseudomonas communities. Environ Microbiol 2018; 20:3629-3642. [PMID: 30003663 DOI: 10.1111/1462-2920.14355] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 06/20/2018] [Accepted: 06/25/2018] [Indexed: 11/28/2022]
Abstract
Many bacteria rely on the secretion of siderophores to scavenge iron from the environment. Laboratory studies revealed that abiotic and biotic factors together determine how much siderophores bacteria make, and whether siderophores can be exploited by non-producing cheaters or be deployed by producers to inhibit competitors. Here, we explore whether these insights apply to natural communities, by comparing the production of the siderophore pyoverdine among 930 Pseudomonas strains from 48 soil and pond communities. We found that pH, iron content, carbon concentration and community diversity determine pyoverdine production levels, and the extent to which strains are either stimulated or inhibited by heterologous (non-self) pyoverdines. While pyoverdine non-producers occurred in both habitats, their prevalence was higher in soils. Environmental and genetic analyses suggest that non-producers can evolve as cheaters, exploiting heterologous pyoverdine, but also due to pyoverdine disuse in environments with increased iron availability. Overall, we found that environmental factors explained between-strain variation in pyoverdine production much better in soils than in ponds, presumably because high strain mixing in ponds impedes local adaption. Our study sheds light on the complexity of natural bacterial communities, and provides first insights into the multivariate nature of siderophore-based iron acquisition and competition among environmental pseudomonads.
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Affiliation(s)
- Elena Butaitė
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
| | - Jos Kramer
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
| | - Stefan Wyder
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
| | - Rolf Kümmerli
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
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16
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Cheating on Cheaters Stabilizes Cooperation in Pseudomonas aeruginosa. Curr Biol 2018; 28:2070-2080.e6. [DOI: 10.1016/j.cub.2018.04.093] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 03/27/2018] [Accepted: 04/27/2018] [Indexed: 01/07/2023]
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17
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Quintero-Galvis JF, Paleo-López R, Solano-Iguaran JJ, Poupin MJ, Ledger T, Gaitan-Espitia JD, Antoł A, Travisano M, Nespolo RF. Exploring the evolution of multicellularity in Saccharomyces cerevisiae under bacteria environment: An experimental phylogenetics approach. Ecol Evol 2018; 8:4619-4630. [PMID: 29760902 PMCID: PMC5938455 DOI: 10.1002/ece3.3979] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 01/23/2018] [Accepted: 02/11/2018] [Indexed: 01/27/2023] Open
Abstract
There have been over 25 independent unicellular to multicellular evolutionary transitions, which have been transformational in the complexity of life. All of these transitions likely occurred in communities numerically dominated by unicellular organisms, mostly bacteria. Hence, it is reasonable to expect that bacteria were involved in generating the ecological conditions that promoted the stability and proliferation of the first multicellular forms as protective units. In this study, we addressed this problem by analyzing the occurrence of multicellularity in an experimental phylogeny of yeasts (Sacharomyces cerevisiae) a model organism that is unicellular but can generate multicellular clusters under some conditions. We exposed a single ancestral population to periodic divergences, coevolving with a cocktail of environmental bacteria that were inoculated to the environment of the ancestor, and compared to a control (no bacteria). We quantified culturable microorganisms to the level of genera, finding up to 20 taxa (all bacteria) that competed with the yeasts during diversification. After 600 generations of coevolution, the yeasts produced two types of multicellular clusters: clonal and aggregative. Whereas clonal clusters were present in both treatments, aggregative clusters were only present under the bacteria treatment and showed significant phylogenetic signal. However, clonal clusters showed different properties if bacteria were present as follows: They were more abundant and significantly smaller than in the control. These results indicate that bacteria are important modulators of the occurrence of multicellularity, providing support to the idea that they generated the ecological conditions-promoting multicellularity.
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Affiliation(s)
| | - Rocío Paleo-López
- Instituto de Ciencias Ambientales y Evolutivas Universidad Austral de Chile Valdivia Chile
| | | | - María Josefina Poupin
- Center of Applied Ecology and Sustainability (CAPES-UC) Facultad de Ciencias Biológicas Universidad Católica de Chile Santiago Chile.,Laboratorio de Bioingeniería Facultad de Ingeniería y Ciencias Universidad Adolfo Ibáñez Santiago Chile
| | - Thomas Ledger
- Center of Applied Ecology and Sustainability (CAPES-UC) Facultad de Ciencias Biológicas Universidad Católica de Chile Santiago Chile.,Laboratorio de Bioingeniería Facultad de Ingeniería y Ciencias Universidad Adolfo Ibáñez Santiago Chile
| | - Juan Diego Gaitan-Espitia
- The Swire Institute of Marine Science and School of Biological Sciences The University of Hong Kong Hong Kong China.,CSIRO Oceans & Atmosphere Hobart TAS Australia
| | - Andrzej Antoł
- Institute of Environmental Sciences Jagiellonian University Kraków Poland
| | - Michael Travisano
- Department of Ecology, Evolution and Behavior University of Minnesota Minneapolis MN USA
| | - Roberto F Nespolo
- Instituto de Ciencias Ambientales y Evolutivas Universidad Austral de Chile Valdivia Chile.,Center of Applied Ecology and Sustainability (CAPES-UC) Facultad de Ciencias Biológicas Universidad Católica de Chile Santiago Chile.,Millennium Institute for Integrative Systems and Synthetic Biology (MIISSB) Santiago Chile
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18
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Harrison F, McNally A, da Silva AC, Heeb S, Diggle SP. Optimised chronic infection models demonstrate that siderophore 'cheating' in Pseudomonas aeruginosa is context specific. THE ISME JOURNAL 2017; 11:2492-2509. [PMID: 28696423 PMCID: PMC5649161 DOI: 10.1038/ismej.2017.103] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/15/2017] [Accepted: 05/17/2017] [Indexed: 12/25/2022]
Abstract
The potential for siderophore mutants of Pseudomonas aeruginosa to attenuate virulence during infection, and the possibility of exploiting this for clinical ends, have attracted much discussion. This has largely been based on the results of in vitro experiments conducted in iron-limited growth medium, in which siderophore mutants act as social 'cheats:' increasing in frequency at the expense of the wild type to result in low-productivity, low-virulence populations dominated by mutants. We show that insights from in vitro experiments cannot necessarily be transferred to infection contexts. First, most published experiments use an undefined siderophore mutant. Whole-genome sequencing of this strain revealed a range of mutations affecting phenotypes other than siderophore production. Second, iron-limited medium provides a very different environment from that encountered in chronic infections. We conducted cheating assays using defined siderophore deletion mutants, in conditions designed to model infected fluids and tissue in cystic fibrosis lung infection and non-healing wounds. Depending on the environment, siderophore loss led to cheating, simple fitness defects, or no fitness effect at all. Our results show that it is crucial to develop defined in vitro models in order to predict whether siderophores are social, cheatable and suitable for clinical exploitation in specific infection contexts.
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Affiliation(s)
- Freya Harrison
- School of Life Sciences, Gibbet Hill Campus, University of Warwick, Coventry, UK
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Alan McNally
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Ana C da Silva
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Stephan Heeb
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Stephen P Diggle
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham, Nottingham, UK
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19
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Schiessl KT, Janssen EML, Kraemer SM, McNeill K, Ackermann M. Magnitude and Mechanism of Siderophore-Mediated Competition at Low Iron Solubility in the Pseudomonas aeruginosa Pyochelin System. Front Microbiol 2017; 8:1964. [PMID: 29085345 PMCID: PMC5649157 DOI: 10.3389/fmicb.2017.01964] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 09/25/2017] [Indexed: 01/28/2023] Open
Abstract
A central question in microbial ecology is whether microbial interactions are predominantly cooperative or competitive. The secretion of siderophores, microbial iron chelators, is a model system for cooperative interactions. However, siderophores have also been shown to mediate competition by sequestering available iron and making it unavailable to competitors. The details of how siderophores mediate competition are not well understood, especially considering the complex distribution of iron phases in the environment. One pertinent question is whether sequestering iron through siderophores can indeed be effective in natural conditions; many natural environments are characterized by large pools of precipitated iron, and it is conceivable that any soluble iron that is sequestered by siderophores is replenished by the dissolution of these precipitated iron sources. Our goal here was to address this issue, and investigate the magnitude and mechanism of siderophore-mediated competition in the presence of precipitated iron. We combined experimental work with thermodynamic modeling, using Pseudomonas aeruginosa as a model system and ferrihydrite precipitates as the iron source with low solubility. Our experiments show that competitive growth inhibition by the siderophore pyochelin is indeed efficient, and that inhibition of a competitor can even have a stronger growth-promoting effect than solubilization of precipitated iron. Based on the results of our thermodynamic models we conclude that the observed inhibition of a competitor is effective because sequestered iron is only very slowly replenished by the dissolution of precipitated iron. Our research highlights the importance of competitive benefits mediated by siderophores, and underlines that the dynamics of siderophore production and uptake in environmental communities could be a signature of competitive, not just cooperative, dynamics.
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Affiliation(s)
- Konstanze T Schiessl
- Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology, Zurich, Switzerland.,Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - Elisabeth M-L Janssen
- Department of Environmental Chemistry, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - Stephan M Kraemer
- Department of Environmental Geosciences, University of Vienna, Vienna, Austria
| | - Kristopher McNeill
- Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Martin Ackermann
- Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology, Zurich, Switzerland.,Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
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20
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Sexton DJ, Schuster M. Nutrient limitation determines the fitness of cheaters in bacterial siderophore cooperation. Nat Commun 2017; 8:230. [PMID: 28794499 PMCID: PMC5550491 DOI: 10.1038/s41467-017-00222-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 06/09/2017] [Indexed: 11/28/2022] Open
Abstract
Cooperative behaviors provide a collective benefit, but are considered costly for the individual. Here, we report that these costs vary dramatically in different contexts and have opposing effects on the selection for non-cooperating cheaters. We investigate a prominent example of bacterial cooperation, the secretion of the peptide siderophore pyoverdine by Pseudomonas aeruginosa, under different nutrient-limiting conditions. Using metabolic modeling, we show that pyoverdine incurs a fitness cost only when its building blocks carbon or nitrogen are growth-limiting and are diverted from cellular biomass production. We confirm this result experimentally with a continuous-culture approach. We show that pyoverdine non-producers (cheaters) enjoy a large fitness advantage in co-culture with producers (cooperators) and spread to high frequency when limited by carbon, but not when limited by phosphorus. The principle of nutrient-dependent fitness costs has implications for the stability of cooperation in pathogenic and non-pathogenic environments, in biotechnological applications, and beyond the microbial realm. Cooperative behaviour among individuals provides a collective benefit, but is considered costly. Using Pseudomonas aeruginosa as a model system, the authors show that secretion of the siderophore pyoverdine only incurs a fitness cost and favours cheating when its building blocks carbon or nitrogen are growth-limiting.
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Affiliation(s)
- D Joseph Sexton
- Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, OR, 97331, USA
| | - Martin Schuster
- Department of Microbiology, Oregon State University, 226 Nash Hall, Corvallis, OR, 97331, USA.
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21
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Zhu Y, Zhang J, Sun Q, Chen Z. Evolutionary dynamics of strategies for threshold snowdrift games on complex networks. Knowl Based Syst 2017. [DOI: 10.1016/j.knosys.2017.05.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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22
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Sexton DJ, Glover RC, Loper JE, Schuster M. Pseudomonas protegens
Pf‐5 favours self‐produced siderophore over free‐loading in interspecies competition for iron. Environ Microbiol 2017. [DOI: 10.1111/1462-2920.13836] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- D. Joseph Sexton
- Department of MicrobiologyOregon State UniversityCorvallis, OR 97331 USA
| | - Rochelle C. Glover
- Department of MicrobiologyOregon State UniversityCorvallis, OR 97331 USA
| | - Joyce E. Loper
- US Department of AgricultureAgricultural Research Service, 3420 N.W. Orchard AveCorvallis, OR 97330 USA
- Department of Botany and Plant PathologyOregon State UniversityCorvallis, OR 97331 USA
| | - Martin Schuster
- Department of MicrobiologyOregon State UniversityCorvallis, OR 97331 USA
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23
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Abstract
Abstract
We study the evolution of cooperation in an interacting particle system with two types. The model we investigate is an extension of a two-type biased voter model. One type (called defector) has a (positive) bias α with respect to the other type (called cooperator). However, a cooperator helps a neighbor (either defector or cooperator) to reproduce at rate γ. We prove that the one-dimensional nearest-neighbor interacting dynamical system exhibits a phase transition at α = γ. A special choice of interaction kernels yield that for α > γ cooperators always die out, but if γ > α, cooperation is the winning strategy.
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24
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Connelly BD, Bruger EL, McKinley PK, Waters CM. Resource abundance and the critical transition to cooperation. J Evol Biol 2017; 30:750-761. [PMID: 28036143 DOI: 10.1111/jeb.13039] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 12/27/2016] [Indexed: 01/06/2023]
Abstract
Cooperation is abundant in nature, occurring at all levels of biological complexity. Yet cooperation is continually threatened by subversion from noncooperating cheaters. Previous studies have shown that cooperation can nevertheless be maintained when the benefits that cooperation provides to relatives outweigh the associated costs. These fitness costs and benefits are not fixed properties, but can be affected by the environment in which populations reside. Here, we describe how one environmental factor, resource abundance, decisively affects the evolution of cooperative public goods production in two independent evolving systems. In the Avida digital evolution platform, populations evolved in environments with different levels of a required resource, whereas populations of Vibrio cholerae evolved in the presence of different nutrient concentrations. In both systems, cooperators and cheaters co-existed stably in resource-rich environments, whereas cheaters dominated in resource-poor environments. These two outcomes were separated by a sharp transition that occurred at a critical level of resource. These results offer new insights into how the environment affects the evolution of cooperation and highlight the challenges that populations of cooperators face when they experience environmental change.
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Affiliation(s)
- B D Connelly
- Department of Computer Science and Engineering, Michigan State University, East Lansing, MI, USA.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA
| | - E L Bruger
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - P K McKinley
- Department of Computer Science and Engineering, Michigan State University, East Lansing, MI, USA.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA
| | - C M Waters
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
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25
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Azevedo AS, Almeida C, Melo LF, Azevedo NF. Impact of polymicrobial biofilms in catheter-associated urinary tract infections. Crit Rev Microbiol 2016; 43:423-439. [PMID: 28033847 DOI: 10.1080/1040841x.2016.1240656] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Recent reports have demonstrated that most biofilms involved in catheter-associated urinary tract infections are polymicrobial communities, with pathogenic microorganisms (e.g. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae) and uncommon microorganisms (e.g. Delftia tsuruhatensis, Achromobacter xylosoxidans) frequently co-inhabiting the same urinary catheter. However, little is known about the interactions that occur between different microorganisms and how they impact biofilm formation and infection outcome. This lack of knowledge affects CAUTIs management as uncommon bacteria action can, for instance, influence the rate at which pathogens adhere and grow, as well as affect the overall biofilm resistance to antibiotics. Another relevant aspect is the understanding of factors that drive a single pathogenic bacterium to become prevalent in a polymicrobial community and subsequently cause infection. In this review, a general overview about the IMDs-associated biofilm infections is provided, with an emphasis on the pathophysiology and the microbiome composition of CAUTIs. Based on the available literature, it is clear that more research about the microbiome interaction, mechanisms of biofilm formation and of antimicrobial tolerance of the polymicrobial consortium are required to better understand and treat these infections.
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Affiliation(s)
- Andreia S Azevedo
- a Department of Chemical Engineering, Faculty of Engineering , Laboratory for Process Engineering, Environment, and Energy and Biotechnology Engineering (LEPABE), University of Porto , Porto , Portugal
| | - Carina Almeida
- a Department of Chemical Engineering, Faculty of Engineering , Laboratory for Process Engineering, Environment, and Energy and Biotechnology Engineering (LEPABE), University of Porto , Porto , Portugal.,b Institute for Biotechnology and Bioengineering (IBB), Centre of Biological Engineering, Universidade do Minho , Braga , Portugal
| | - Luís F Melo
- a Department of Chemical Engineering, Faculty of Engineering , Laboratory for Process Engineering, Environment, and Energy and Biotechnology Engineering (LEPABE), University of Porto , Porto , Portugal
| | - Nuno F Azevedo
- a Department of Chemical Engineering, Faculty of Engineering , Laboratory for Process Engineering, Environment, and Energy and Biotechnology Engineering (LEPABE), University of Porto , Porto , Portugal
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26
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Nutrient reduction induced stringent responses promote bacterial quorum-sensing divergence for population fitness. Sci Rep 2016; 6:34925. [PMID: 27713502 PMCID: PMC5054682 DOI: 10.1038/srep34925] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 09/20/2016] [Indexed: 02/05/2023] Open
Abstract
Bacteria use a cell-cell communication system termed quorum-sensing (QS) to adjust population size by coordinating the costly but beneficial cooperative behaviors. It has long been suggested that bacterial social conflict for expensive extracellular products may drive QS divergence and cause the “tragedy of the commons”. However, the underlying molecular mechanism of social divergence and its evolutionary consequences for the bacterial ecology still remain largely unknown. By using the model bacterium Pseudomonas aeruginosa PAO1, here we show that nutrient reduction can promote QS divergence for population fitness during evolution but requiring adequate cell density. Mechanically, decreased nutrient supplies can induce RpoS-directed stringent response and enhance the selection pressure on lasR gene, and lasR mutants are evolved in association with the DNA mismatch repair “switch-off”. The lasR mutants have higher relative fitness than QS-intact individuals due to their energy-saving characteristic under nutrient decreased condition. Furthermore an optimal incorporation of lasR mutants is capable of maximizing the fitness of entire population during in vitro culture and the colonization in mouse lung. Consequently, rather than worsen the population health, QS-coordinated social divergence is an elaborate evolutionary strategy that renders the entire bacterial population more fit in tough times.
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27
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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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28
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Abstract
Microbial adaptation is conspicuous in essentially every environment, but the mechanisms of adaptive evolution are poorly understood. Studying evolution in the laboratory under controlled conditions can be a tractable approach, particularly when new, discernible phenotypes evolve rapidly. This is especially the case in the spatially structured environments of biofilms, which promote the occurrence and stability of new, heritable phenotypes. Further, diversity in biofilms can give rise to nascent social interactions among coexisting mutants and enable the study of the emerging field of sociomicrobiology. Here, we review findings from laboratory evolution experiments with either Pseudomonas fluorescens or Burkholderia cenocepacia in spatially structured environments that promote biofilm formation. In both systems, ecotypes with overlapping niches evolve and produce competitive or facilitative interactions that lead to novel community attributes, demonstrating the parallelism of adaptive processes captured in the lab.
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29
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Abstract
A trait-based approach focuses on attributes of taxa that influence the structure and function of communities. Biofilm production is a common trait among microorganisms in a wide range of environmental, engineered, and host-associated ecosystems. Here, we used Pseudomonas aeruginosa to link biofilm production to moisture availability, a common stressor for microorganisms in soil. First, we demonstrate that biofilm production is a response trait that influences the desiccation phenotype by increasing survivorship, shifting the niche space, and reducing the minimum water potential needed to sustain a net-positive growth rate (Ψ*). Although the allocation of resources to biofilms is thought to be costly, we found no evidence for a trade-off between fitness and biofilm production along a soil moisture gradient. Second, we demonstrated that biofilm production is an effect trait. Specifically, biofilm production increased water retention in soils that were exposed to a series of drying and rewetting cycles. Although this form of niche construction should affect species interactions, we found no evidence that the benefits of biofilm production were extended to another co-occurring soil bacterium. Together, our results support the view that biofilm production is an important trait that may contribute to the distribution, abundance, and functioning of microorganisms in soils.
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Affiliation(s)
- Jay T Lennon
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Brent K Lehmkuhl
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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30
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smith J, Strassmann JE, Queller DC. Fine-scale spatial ecology drives kin selection relatedness among cooperating amoebae. Evolution 2016; 70:848-59. [DOI: 10.1111/evo.12895] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 02/09/2016] [Accepted: 02/11/2016] [Indexed: 12/29/2022]
Affiliation(s)
- jeff smith
- Department of Biology; Washington University in St. Louis; Saint Louis Missouri 63130
| | - Joan E. Strassmann
- Department of Biology; Washington University in St. Louis; Saint Louis Missouri 63130
| | - David C. Queller
- Department of Biology; Washington University in St. Louis; Saint Louis Missouri 63130
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31
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Waite AJ, Cannistra C, Shou W. Defectors Can Create Conditions That Rescue Cooperation. PLoS Comput Biol 2015; 11:e1004645. [PMID: 26690946 PMCID: PMC4687000 DOI: 10.1371/journal.pcbi.1004645] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Accepted: 11/05/2015] [Indexed: 11/18/2022] Open
Abstract
Cooperation based on the production of costly common goods is observed throughout nature. This is puzzling, as cooperation is vulnerable to exploitation by defectors which enjoy a fitness advantage by consuming the common good without contributing fairly. Depletion of the common good can lead to population collapse and the destruction of cooperation. However, population collapse implies small population size, which, in a structured population, is known to favor cooperation. This happens because small population size increases variability in cooperator frequency across different locations. Since individuals in cooperator-dominated locations (which are most likely cooperators) will grow more than those in defector-dominated locations (which are most likely defectors), cooperators can outgrow defectors globally despite defectors outgrowing cooperators in each location. This raises the possibility that defectors can lead to conditions that sometimes rescue cooperation from defector-induced destruction. We demonstrate multiple mechanisms through which this can occur, using an individual-based approach to model stochastic birth, death, migration, and mutation events. First, during defector-induced population collapse, defectors occasionally go extinct before cooperators by chance, which allows cooperators to grow. Second, empty locations, either preexisting or created by defector-induced population extinction, can favor cooperation because they allow cooperator but not defector migrants to grow. These factors lead to the counterintuitive result that the initial presence of defectors sometimes allows better survival of cooperation compared to when defectors are initially absent. Finally, we find that resource limitation, inducible by defectors, can select for mutations adaptive to resource limitation. When these mutations are initially present at low levels or continuously generated at a moderate rate, they can favor cooperation by further reducing local population size. We predict that in a structured population, small population sizes precipitated by defectors provide a "built-in" mechanism for the persistence of cooperation.
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Affiliation(s)
- Adam James Waite
- Molecular and Cellular Biology Program, University of Washington, Seattle, Washington, United States of America
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- * E-mail: (AJW); (WS)
| | - Caroline Cannistra
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Wenying Shou
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- * E-mail: (AJW); (WS)
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Vasse M, Torres-Barceló C, Hochberg ME. Phage selection for bacterial cheats leads to population decline. Proc Biol Sci 2015; 282:20152207. [PMID: 26538598 PMCID: PMC4650167 DOI: 10.1098/rspb.2015.2207] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 10/08/2015] [Indexed: 11/12/2022] Open
Abstract
While predators and parasites are known for their effects on bacterial population biology, their impact on the dynamics of bacterial social evolution remains largely unclear. Siderophores are iron-chelating molecules that are key to the survival of certain bacterial species in iron-limited environments, but their production can be subject to cheating by non-producing genotypes. In a selection experiment conducted over approximately 20 bacterial generations and involving 140 populations of the pathogenic bacterium Pseudomonas aeruginosa PAO1, we assessed the impact of a lytic phage on competition between siderophore producers and non-producers. We show that the presence of lytic phages favours the non-producing genotype in competition, regardless of whether iron use relies on siderophores. Interestingly, phage pressure resulted in higher siderophore production, which constitutes a cost to the producers and may explain why they were outcompeted by non-producers. By the end of the experiment, however, cheating load reduced the fitness of mixed populations relative to producer monocultures, and only monocultures of producers managed to grow in the presence of phage in situations where siderophores were necessary to access iron. These results suggest that public goods production may be modulated in the presence of natural enemies with consequences for the evolution of social strategies.
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Affiliation(s)
- Marie Vasse
- Institut des Sciences de l'Evolution, CNRS-Université de Montpellier, Place Eugène Bataillon, Montpellier Cedex 5 34095, France
| | - Clara Torres-Barceló
- Institut des Sciences de l'Evolution, CNRS-Université de Montpellier, Place Eugène Bataillon, Montpellier Cedex 5 34095, France
| | - Michael E Hochberg
- Institut des Sciences de l'Evolution, CNRS-Université de Montpellier, Place Eugène Bataillon, Montpellier Cedex 5 34095, France Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA
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Kümmerli R, Santorelli LA, Granato ET, Dumas Z, Dobay A, Griffin AS, West SA. Co-evolutionary dynamics between public good producers and cheats in the bacterium Pseudomonas aeruginosa. J Evol Biol 2015; 28:2264-74. [PMID: 26348785 DOI: 10.1111/jeb.12751] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 08/17/2015] [Indexed: 01/20/2023]
Abstract
The production of beneficial public goods is common in the microbial world, and so is cheating--the exploitation of public goods by nonproducing mutants. Here, we examine co-evolutionary dynamics between cooperators and cheats and ask whether cooperators can evolve strategies to reduce the burden of exploitation, and whether cheats in turn can improve their exploitation abilities. We evolved cooperators of the bacterium Pseudomonas aeruginosa, producing the shareable iron-scavenging siderophore pyoverdine, together with cheats, defective in pyoverdine production but proficient in uptake. We found that cooperators managed to co-exist with cheats in 56% of all replicates over approximately 150 generations of experimental evolution. Growth and competition assays revealed that co-existence was fostered by a combination of general adaptions to the media and specific adaptions to the co-evolving opponent. Phenotypic screening and whole-genome resequencing of evolved clones confirmed this pattern, and suggest that cooperators became less exploitable by cheats because they significantly reduced their pyoverdine investment. Cheats, meanwhile, improved exploitation efficiency through mutations blocking the costly pyoverdine-signalling pathway. Moreover, cooperators and cheats evolved reduced motility, a pattern that likely represents adaptation to laboratory conditions, but at the same time also affects social interactions by reducing strain mixing and pyoverdine sharing. Overall, we observed parallel evolution, where co-existence of cooperators and cheats was enabled by a combination of adaptations to the abiotic and social environment and their interactions.
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Affiliation(s)
- R Kümmerli
- Microbial Evolutionary Ecology, Institute of Plant Biology, University of Zürich, Zürich, Switzerland.,Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
| | | | - E T Granato
- Microbial Evolutionary Ecology, Institute of Plant Biology, University of Zürich, Zürich, Switzerland
| | - Z Dumas
- Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland.,Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - A Dobay
- Institute of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland
| | - A S Griffin
- Department of Zoology, University of Oxford, Oxford, UK
| | - S A West
- Department of Zoology, University of Oxford, Oxford, UK
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Asfahl KL, Walsh J, Gilbert K, Schuster M. Non-social adaptation defers a tragedy of the commons in Pseudomonas aeruginosa quorum sensing. THE ISME JOURNAL 2015; 9:1734-46. [PMID: 25615439 PMCID: PMC4511930 DOI: 10.1038/ismej.2014.259] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Revised: 12/04/2014] [Accepted: 12/05/2014] [Indexed: 02/02/2023]
Abstract
In a process termed quorum sensing (QS), the opportunistic bacterial pathogen Pseudomonas aeruginosa uses diffusible signaling molecules to regulate the expression of numerous secreted factors or public goods that are shared within the population. But not all cells respond to QS signals. These social cheaters typically harbor a mutation in the QS receptor gene lasR and exploit the public goods produced by cooperators. Here we show that non-social adaptation under growth conditions that require QS-dependent public goods increases tolerance to cheating and defers a tragedy of the commons. The underlying mutation is in the transcriptional repressor gene psdR. This mutation has no effect on public goods expression but instead increases individual fitness by derepressing growth-limiting intracellular metabolism. Even though psdR mutant populations remain susceptible to invasion by isogenic psdR lasR cheaters, they bear a lower cheater load than do wild-type populations, and they are completely resistant to invasion by lasR cheaters with functional psdR. Mutations in psdR also sustain growth near wild-type levels when paired with certain partial loss-of-function lasR mutations. Targeted sequencing of multiple evolved isolates revealed that mutations in psdR arise before mutations in lasR, and rapidly sweep through the population. Our results indicate that a QS-favoring environment can lead to adaptations in non-social, intracellular traits that increase the fitness of cooperating individuals and thereby contribute to population-wide maintenance of QS and associated cooperative behaviors.
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Affiliation(s)
- Kyle L Asfahl
- Department of Microbiology, Oregon State University, Corvallis, OR, USA
| | - Jessica Walsh
- Department of Microbiology, Oregon State University, Corvallis, OR, USA
| | - Kerrigan Gilbert
- Department of Microbiology, Oregon State University, Corvallis, OR, USA
| | - Martin Schuster
- Department of Microbiology, Oregon State University, Corvallis, OR, USA
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Ducasse H, Arnal A, Vittecoq M, Daoust SP, Ujvari B, Jacqueline C, Tissot T, Ewald P, Gatenby RA, King KC, Bonhomme F, Brodeur J, Renaud F, Solary E, Roche B, Thomas F. Cancer: an emergent property of disturbed resource-rich environments? Ecology meets personalized medicine. Evol Appl 2015; 8:527-40. [PMID: 26136819 PMCID: PMC4479509 DOI: 10.1111/eva.12232] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 10/17/2015] [Indexed: 12/13/2022] Open
Abstract
For an increasing number of biologists, cancer is viewed as a dynamic system governed by evolutionary and ecological principles. Throughout most of human history, cancer was an uncommon cause of death and it is generally accepted that common components of modern culture, including increased physiological stresses and caloric intake, favor cancer development. However, the precise mechanisms for this linkage are not well understood. Here, we examine the roles of ecological and physiological disturbances and resource availability on the emergence of cancer in multicellular organisms. We argue that proliferation of 'profiteering phenotypes' is often an emergent property of disturbed, resource-rich environments at all scales of biological organization. We review the evidence for this phenomenon, explore it within the context of malignancy, and discuss how this ecological framework may offer a theoretical background for novel strategies of cancer prevention. This work provides a compelling argument that the traditional separation between medicine and evolutionary ecology remains a fundamental limitation that needs to be overcome if complex processes, such as oncogenesis, are to be completely understood.
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Affiliation(s)
- Hugo Ducasse
- MIVEGEC, UMR IRD/CNRS/UM 5290Montpellier Cedex 5, France
- CREEC, Université Montpellier 2Montpellier Cedex 5, France
| | - Audrey Arnal
- MIVEGEC, UMR IRD/CNRS/UM 5290Montpellier Cedex 5, France
- CREEC, Université Montpellier 2Montpellier Cedex 5, France
| | - Marion Vittecoq
- MIVEGEC, UMR IRD/CNRS/UM 5290Montpellier Cedex 5, France
- CREEC, Université Montpellier 2Montpellier Cedex 5, France
- Centre de Recherche de la Tour du ValatArles, France
| | - Simon P Daoust
- Department of Biology, John Abbott CollegeSainte-Anne-de-Bellevue, QC, Canada
| | - Beata Ujvari
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin UniversityWaurn Ponds, Vic., Australia
| | - Camille Jacqueline
- MIVEGEC, UMR IRD/CNRS/UM 5290Montpellier Cedex 5, France
- CREEC, Université Montpellier 2Montpellier Cedex 5, France
| | - Tazzio Tissot
- MIVEGEC, UMR IRD/CNRS/UM 5290Montpellier Cedex 5, France
- CREEC, Université Montpellier 2Montpellier Cedex 5, France
| | - Paul Ewald
- Department of Biology and the Program on Disease Evolution, University of LouisvilleLouisville, KY, USA
| | - Robert A Gatenby
- Department of Radiology, H. Lee Moffitt Cancer Center & Research InstituteTampa, FL, USA
| | - Kayla C King
- Department of Zoology, University of OxfordOxford, UK
| | - François Bonhomme
- ISEM Institut des sciences de l'évolution, Université Montpellier 2, CNRS/IRD/UM2 UMR 5554Montpellier Cedex, France
| | - Jacques Brodeur
- Institut de Recherche en Biologie Végétale, Université de MontréalMontréal, QC, Canada
| | - François Renaud
- MIVEGEC, UMR IRD/CNRS/UM 5290Montpellier Cedex 5, France
- CREEC, Université Montpellier 2Montpellier Cedex 5, France
| | - Eric Solary
- INSERM U1009, Université Paris-Sud, Gustave RoussyVillejuif, France
| | - Benjamin Roche
- MIVEGEC, UMR IRD/CNRS/UM 5290Montpellier Cedex 5, France
- CREEC, Université Montpellier 2Montpellier Cedex 5, France
- Unité mixte internationale de Modélisation Mathématique et Informatique des Systèmes Complexes (UMI IRD/UPMC UMMISCO)BondyCedex, France
| | - Frédéric Thomas
- MIVEGEC, UMR IRD/CNRS/UM 5290Montpellier Cedex 5, France
- CREEC, Université Montpellier 2Montpellier Cedex 5, France
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Brockhurst MA. Experimental evolution can unravel the complex causes of natural selection in clinical infections. MICROBIOLOGY-SGM 2015; 161:1175-9. [PMID: 25957311 DOI: 10.1099/mic.0.000107] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
It is increasingly clear that rapid evolutionary dynamics are an important process in microbial ecology. Experimental evolution, wherein microbial evolution is observed in real-time, has revealed many instances of appreciable evolutionary change occurring on very short timescales of a few days or weeks in response to a variety of biotic and abiotic selection pressures. From clinical infections, including the chronic bacterial lung infections associated with cystic fibrosis that form a focus of my research, there is now abundant evidence suggesting that rapid evolution by infecting microbes contributes to host adaptation, treatment failure and worsening patient prognosis. However, disentangling the drivers of natural selection in complex infection environments is extremely challenging and limits our understanding of the selective pressures acting upon microbes in infections. Controlled evolution experiments can make a vital contribution to this by determining the causal links between predicted drivers of natural selection and the evolutionary responses of microbes. Integration of experimental evolution into studies of clinical infections is a key next step towards a better understanding of the causes and consequences of rapid microbial evolution in infections, and discovering how these evolutionary processes might be influenced to improve patient health.A video of this Prize Lecture, presented at the Society for General Microbiology Annual Conference 2015, can be viewed via this link: Michael A. Brockhurst https://www.youtube.com/watch?v=N1bodVSl27E.
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O'Brien S, Hodgson DJ, Buckling A. Social evolution of toxic metal bioremediation in Pseudomonas aeruginosa. Proc Biol Sci 2015; 281:rspb.2014.0858. [PMID: 24898376 PMCID: PMC4071558 DOI: 10.1098/rspb.2014.0858] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Bacteria are often iron-limited, and hence produce extracellular iron-scavenging siderophores. A crucial feature of siderophore production is that it can be an altruistic behaviour (individually costly but benefitting neighbouring cells), thus siderophore producers can be invaded by non-producing social 'cheats'. Recent studies have shown that siderophores can also bind other heavy metals (such as Cu and Zn), but in this case siderophore chelation actually reduces metal uptake by bacteria. These complexes reduce heavy metal toxicity, hence siderophore production may contribute to toxic metal bioremediation. Here, we show that siderophore production in the context of bioremediation is also an altruistic trait and can be exploited by cheating phenotypes in the opportunistic pathogen Pseudomonas aeruginosa. Specifically, we show that in toxic copper concentrations (i) siderophore non-producers evolve de novo and reach high frequencies, and (ii) producing strains are fitter than isogenic non-producing strains in monoculture, and vice versa in co-culture. Moreover, we show that the evolutionary effect copper has on reducing siderophore production is greater than the reduction observed under iron-limited conditions. We discuss the relevance of these results to the evolution of siderophore production in natural communities and heavy metal bioremediation.
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Affiliation(s)
- Siobhán O'Brien
- Department of Biosciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - David J Hodgson
- Department of Biosciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Angus Buckling
- Department of Biosciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
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38
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Dobay A, Bagheri HC, Messina A, Kümmerli R, Rankin DJ. Interaction effects of cell diffusion, cell density and public goods properties on the evolution of cooperation in digital microbes. J Evol Biol 2014; 27:1869-77. [PMID: 24962623 DOI: 10.1111/jeb.12437] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 05/12/2014] [Accepted: 05/21/2014] [Indexed: 11/30/2022]
Abstract
Microbial cooperation typically consists in the sharing of secreted metabolites (referred to as public goods) within the community. Although public goods generally promote population growth, they are also vulnerable to exploitation by cheating mutants, which no longer contribute, but still benefit from the public goods produced by others. Although previous studies have identified a number of key factors that prevent the spreading of cheaters, little is known about how these factors interact and jointly shape the evolution of microbial cooperation. Here, we address this issue by investigating the interaction effects of cell diffusion, cell density, public good diffusion and durability (factors known to individually influence costs and benefits of public goods production) on selection for cooperation. To be able to quantify these effects across a wide parameter space, we developed an individual-based simulation platform, consisting of digital cooperator and cheater bacteria inhabiting a finite two-dimensional continuous toroidal surface. Our simulations, which closely mimic microbial microcolony growth, revealed that: (i) either reduced cell diffusion (which keeps cooperators together) or reduced public good diffusion (which keeps the public goods closer to the producer) is not only essential but also sufficient for cooperation to be promoted; (ii) the sign of selection for or against cooperation can change as a function of cell density and in interaction with diffusion parameters; and (iii) increased public goods durability has opposing effects on the evolution of cooperation depending on the level of cell and public good diffusion. Our work highlights that interactions between key parameters of public goods cooperation give rise to complex fitness landscapes, a finding that calls for multifactorial approaches when studying microbial cooperation in natural systems.
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Affiliation(s)
- A Dobay
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
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Bourke AFG. Hamilton's rule and the causes of social evolution. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130362. [PMID: 24686934 DOI: 10.1098/rstb.2013.0362] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Hamilton's rule is a central theorem of inclusive fitness (kin selection) theory and predicts that social behaviour evolves under specific combinations of relatedness, benefit and cost. This review provides evidence for Hamilton's rule by presenting novel syntheses of results from two kinds of study in diverse taxa, including cooperatively breeding birds and mammals and eusocial insects. These are, first, studies that empirically parametrize Hamilton's rule in natural populations and, second, comparative phylogenetic analyses of the genetic, life-history and ecological correlates of sociality. Studies parametrizing Hamilton's rule are not rare and demonstrate quantitatively that (i) altruism (net loss of direct fitness) occurs even when sociality is facultative, (ii) in most cases, altruism is under positive selection via indirect fitness benefits that exceed direct fitness costs and (iii) social behaviour commonly generates indirect benefits by enhancing the productivity or survivorship of kin. Comparative phylogenetic analyses show that cooperative breeding and eusociality are promoted by (i) high relatedness and monogamy and, potentially, by (ii) life-history factors facilitating family structure and high benefits of helping and (iii) ecological factors generating low costs of social behaviour. Overall, the focal studies strongly confirm the predictions of Hamilton's rule regarding conditions for social evolution and their causes.
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Affiliation(s)
- Andrew F G Bourke
- School of Biological Sciences, University of East Anglia, , Norwich Research Park, Norwich NR4 7TJ, UK
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40
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Kümmerli R, Ross-Gillespie A. EXPLAINING THE SOCIOBIOLOGY OF PYOVERDIN PRODUCINGPSEUDOMONAS: A COMMENT ON ZHANG AND RAINEY (2013). Evolution 2013; 68:3337-43. [DOI: 10.1111/evo.12311] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Accepted: 10/30/2013] [Indexed: 01/10/2023]
Affiliation(s)
- Rolf Kümmerli
- Institute of Plant Biology; University of Zürich; Winterthurerstrasse 190 8057 Zürich Switzerland
| | - Adin Ross-Gillespie
- Institute of Plant Biology; University of Zürich; Winterthurerstrasse 190 8057 Zürich Switzerland
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41
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Harrison F. Dynamic social behaviour in a bacterium: pseudomonas aeruginosa partially compensates for siderophore loss to cheats. J Evol Biol 2013; 26:1370-8. [PMID: 23662904 DOI: 10.1111/jeb.12126] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 12/20/2012] [Accepted: 01/10/2013] [Indexed: 11/28/2022]
Abstract
Cooperation underlies diverse phenomena including the origins of multicellular life, human behaviour in economic markets and the mechanisms by which pathogenic bacteria cause disease. Experiments with microorganisms have advanced our understanding of how, when and why cooperation evolves, but the extent to which microbial cooperation can recapitulate aspects of animal behaviour is debated. For instance, understanding the evolution of behavioural response rules (how should one individual respond to another's decision to cooperate or defect?) is a key part of social evolution theory, but the possible existence of such rules in social microbes has not been explored. In one specific context (biparental care in animals), cooperation is maintained if individuals respond to a partner's defection by increasing their own investment into cooperation, but not so much that this fully compensates for the defector's lack of investment. This is termed 'partial compensation'. Here, I show that partial compensation for the presence of noncooperating 'cheats' is also observed in a microbial social behaviour: the cooperative production of iron-scavenging siderophores by the bacterium Pseudomonas aeruginosa. A period of evolution in the presence of cheats maintains this response, whereas evolution in the absence of cheats leads to a loss of compensatory behaviour. These results demonstrate (i) the remarkable flexibility of bacterial social behaviour, (ii) the potential generality of partial compensation as a social response rule and (iii) the need for mathematical models to explore the evolution of response rules in multi-player social interactions.
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Affiliation(s)
- F Harrison
- Department of Zoology, University of Oxford, Oxford, United Kingdom.
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42
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Sanchez A, Gore J. feedback between population and evolutionary dynamics determines the fate of social microbial populations. PLoS Biol 2013; 11:e1001547. [PMID: 23637571 PMCID: PMC3640081 DOI: 10.1371/journal.pbio.1001547] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 03/14/2013] [Indexed: 11/24/2022] Open
Abstract
A new study finds that the evolution of social genes may be coupled with population dynamics, and may dramatically affect ecological resilience, particularly in the face of rapidly deteriorating environments. The evolutionary spread of cheater strategies can destabilize populations engaging in social cooperative behaviors, thus demonstrating that evolutionary changes can have profound implications for population dynamics. At the same time, the relative fitness of cooperative traits often depends upon population density, thus leading to the potential for bi-directional coupling between population density and the evolution of a cooperative trait. Despite the potential importance of these eco-evolutionary feedback loops in social species, they have not yet been demonstrated experimentally and their ecological implications are poorly understood. Here, we demonstrate the presence of a strong feedback loop between population dynamics and the evolutionary dynamics of a social microbial gene, SUC2, in laboratory yeast populations whose cooperative growth is mediated by the SUC2 gene. We directly visualize eco-evolutionary trajectories of hundreds of populations over 50–100 generations, allowing us to characterize the phase space describing the interplay of evolution and ecology in this system. Small populations collapse despite continual evolution towards increased cooperative allele frequencies; large populations with a sufficient number of cooperators “spiral” to a stable state of coexistence between cooperator and cheater strategies. The presence of cheaters does not significantly affect the equilibrium population density, but it does reduce the resilience of the population as well as its ability to adapt to a rapidly deteriorating environment. Our results demonstrate the potential ecological importance of coupling between evolutionary dynamics and the population dynamics of cooperatively growing organisms, particularly in microbes. Our study suggests that this interaction may need to be considered in order to explain intraspecific variability in cooperative behaviors, and also that this feedback between evolution and ecology can critically affect the demographic fate of those species that rely on cooperation for their survival. The fact that rapid evolution within a species can cause dramatic ecological changes has only recently begun to be appreciated. In particular, it has often been assumed that population dynamics, controlled by ecological circumstances such as the presence of predators or disease, occur at such different timescales compared with evolutionary dynamics that they are effectively de-coupled. Recent studies, however, have found that evolution can occur over ecological timescales and thus may have important effects on ecological dynamics. Here, we demonstrate the presence of a tight coupling between population dynamics and the evolutionary dynamics of a “social” microbial gene, which allows a laboratory population of budding yeast to cooperatively break down sucrose and grow on the simpler sugars released from it. In such cooperative populations, evolution may favor non-cooperative, or “cheater” individuals that do not contribute to the public good (in this case, the products of sucrose break down), but still use that public good to grow at the expense of the individuals that do cooperate. Our study shows that a population of cooperators that is invaded by cheaters does not collapse as a result of cheater proliferation but can evolve to a viable equilibrium. However, the coexisting population is less resilient to perturbations.
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Affiliation(s)
- Alvaro Sanchez
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * E-mail: (AS); (JG)
| | - Jeff Gore
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * E-mail: (AS); (JG)
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Triggle DJ. Nous Sommes Tous des Bacteries: Implications for medicine, pharmacology and public health. Biochem Pharmacol 2012; 84:1543-50. [DOI: 10.1016/j.bcp.2012.08.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 08/01/2012] [Accepted: 08/06/2012] [Indexed: 02/08/2023]
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44
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Hoffmann K, Foster KR, Korb J. Nest value mediates reproductive decision making within termite societies. Behav Ecol 2012. [DOI: 10.1093/beheco/ars103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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45
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Celiker H, Gore J. Cellular cooperation: insights from microbes. Trends Cell Biol 2012; 23:9-15. [PMID: 22999189 DOI: 10.1016/j.tcb.2012.08.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 08/24/2012] [Accepted: 08/30/2012] [Indexed: 11/30/2022]
Abstract
Cooperation between cells is a widespread phenomenon in nature, found across diverse systems ranging from microbial populations to multicellular organisms. For cooperation to evolve and be maintained within a population of cells, costs due to competition have to be outweighed by the benefits gained through cooperative actions. Because cooperation generally confers a cost to the cooperating cells, defector cells that do not cooperate but reap the benefits of cooperation can thrive and eventually drive the cooperating phenotypes to extinction. Here we summarize recent advances made in understanding how cooperation and multicellularity can evolve in microbial populations in the face of such conflicts and discuss parallels with cell populations within multicellular organisms.
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Monson R, Burr T, Carlton T, Liu H, Hedley P, Toth I, Salmond GP. Identification of genes in the VirR regulon ofPectobacterium atrosepticumand characterization of their roles in quorum sensing-dependent virulence. Environ Microbiol 2012; 15:687-701. [DOI: 10.1111/j.1462-2920.2012.02822.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Dumas Z, Kümmerli R. Cost of cooperation rules selection for cheats in bacterial metapopulations. J Evol Biol 2011; 25:473-84. [PMID: 22168669 DOI: 10.1111/j.1420-9101.2011.02437.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Bacteria secrete a large variety of beneficial metabolites into the environment, which can be shared as public goods among producing bacteria, but also be exploited by nonproducing cheats. Here, we focus on cooperative production of iron-chelating molecules (siderophores) in the bacterium Pseudomonas aeruginosa to study how relevant ecological factors influence selection for cheating. We designed patch-structured metapopulations that allowed us introducing among-patch ecological variation. We found that cheating readily evolved in uniform iron-limited environments. This finding is explained by severe iron limitation demanding high siderophore-production efforts, which results in high metabolic costs accruing to cooperators, and thereby facilitates the spread of cheats. In contrast, we observed a significant reduction or even negation of selection for cheating in metapopulations where we introduced patches with increased iron availability and/or opportunities to recycle siderophores. These findings are compatible with the view that cheats are less likely to invade in environments that allow bacteria to reduce siderophore-production efforts, as this lowers the overall metabolic costs accruing to cooperators. Because we increased iron availability and siderophore recycling opportunities moderately, and only in some patches, our findings demonstrate that already-small local variations in ecological conditions as occurring in nature can significantly affect selection for public-goods secretion in microbes. In addition, we found that most (84.6%) of the evolved cheats were partially deficient for siderophore production and not loss-of-function mutants. Genetic considerations indicate that mutations leading to partial deficiency occur more frequent than mutations leading to loss of function, but also suggest that partially deficient mutants might often be the more competitive cheats.
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Affiliation(s)
- Z Dumas
- Swiss Federal Institute of Aquatic Science and Technology (Eawag), Environmental Microbiology, Dübendorf, Switzerland
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Tzamali E, Poirazi P, Tollis IG, Reczko M. A computational exploration of bacterial metabolic diversity identifying metabolic interactions and growth-efficient strain communities. BMC SYSTEMS BIOLOGY 2011; 5:167. [PMID: 22008379 PMCID: PMC3212978 DOI: 10.1186/1752-0509-5-167] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 10/18/2011] [Indexed: 12/31/2022]
Abstract
Background Metabolic interactions involve the exchange of metabolic products among microbial species. Most microbes live in communities and usually rely on metabolic interactions to increase their supply for nutrients and better exploit a given environment. Constraint-based models have successfully analyzed cellular metabolism and described genotype-phenotype relations. However, there are only a few studies of genome-scale multi-species interactions. Based on genome-scale approaches, we present a graph-theoretic approach together with a metabolic model in order to explore the metabolic variability among bacterial strains and identify and describe metabolically interacting strain communities in a batch culture consisting of two or more strains. We demonstrate the applicability of our approach to the bacterium E. coli across different single-carbon-source conditions. Results A different diversity graph is constructed for each growth condition. The graph-theoretic properties of the constructed graphs reflect the inherent high metabolic redundancy of the cell to single-gene knockouts, reveal mutant-hubs of unique metabolic capabilities regarding by-production, demonstrate consistent metabolic behaviors across conditions and show an evolutionary difficulty towards the establishment of polymorphism, while suggesting that communities consisting of strains specifically adapted to a given condition are more likely to evolve. We reveal several strain communities of improved growth relative to corresponding monocultures, even though strain communities are not modeled to operate towards a collective goal, such as the community growth and we identify the range of metabolites that are exchanged in these batch co-cultures. Conclusions This study provides a genome-scale description of the metabolic variability regarding by-production among E. coli strains under different conditions and shows how metabolic differences can be used to identify metabolically interacting strain communities. This work also extends the existing stoichiometric models in order to describe batch co-cultures and provides the extent of metabolic interactions in a strain community revealing their importance for growth.
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Affiliation(s)
- Eleftheria Tzamali
- Computer Science Department, University of Crete, P.O. Box 2208, Heraklion, 71409, Greece.
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A fitness trade-off between local competition and dispersal in Vibrio cholerae biofilms. Proc Natl Acad Sci U S A 2011; 108:14181-5. [PMID: 21825170 DOI: 10.1073/pnas.1111147108] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Bacteria commonly grow in densely populated surface-bound communities, termed biofilms, where they gain benefits including superior access to nutrients and resistance to environmental insults. The secretion of extracellular polymeric substances (EPS), which bind bacterial collectives together, is ubiquitously associated with biofilm formation. It is generally assumed that EPS secretion is a cooperative phenotype that benefits all neighboring cells, but in fact little is known about the competitive and evolutionary dynamics of EPS production. By studying Vibrio cholerae biofilms in microfluidic devices, we show that EPS-producing cells selectively benefit their clonemates and gain a dramatic advantage in competition against an isogenic EPS-deficient strain. However, this advantage carries an ecological cost beyond the energetic requirement for EPS production: EPS-producing cells are impaired for dispersal to new locations. Our study establishes that a fundamental tradeoff between local competition and dispersal exists among bacteria. Furthermore, this tradeoff can be governed by a single phenotype.
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Abstract
Although cooperation is a widespread phenomenon in nature, human cooperation exceeds that of all other species with regard to the scale and range of cooperative activities. Here we review and discuss differences between humans and non-humans in the strategies employed to maintain cooperation and control free-riders. We distinguish forms of cooperative behaviour based on their influence on the immediate payoffs of actor and recipient. If the actor has immediate costs and only the recipient obtains immediate benefits, we term this investment. If the behaviour has immediate positive effects for both actor and recipient, we call this a self-serving mutually beneficial behaviour or mutual cooperation. We argue that humans, in contrast to all other species, employ a wider range of enforcement mechanisms, which allow higher levels of cooperation to evolve and stabilize among unrelated individuals and in large groups. We also discuss proximate mechanisms underlying cooperative behaviour and focus on our experimental work with humans and our closest primate relatives. Differences in the proximate mechanisms also seem to contribute to explaining humans' greater ability to cooperate and enforce cooperation.
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Affiliation(s)
- Alicia P Melis
- Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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