Co-evolutionary dynamics of collective action with signaling for a quorum

Collective signaling for a quorum is found in a wide range of organisms that face collective action problems whose successful solution requires the participation of some quorum of the individuals present. These range from humans, to social insects, to bacteria. The mechanisms involved, the quorum required, and the size of the group may vary. Here we address the general question of the evolution of collective signaling at a high level of abstraction. We investigate the evolutionary dynamics of a population engaging in a signaling N-person game theoretic model. Parameter settings allow for loners and cheaters, and for costly or costless signals. We find a rich dynamics, showing how natural selection, operating on a population of individuals endowed with the simplest strategies, is able to evolve a costly signaling system that allows individuals to respond appropriately to different states of Nature. Signaling robustly promotes cooperative collective action, in particular when coordinated action is most needed and difficult to achieve. Two different signaling systems may emerge depending on Nature's most prevalent states.Funding: This research was supported by FEDER through POFC - COMPETE, FCT-Portugal through grants SFRH/BD/86465/2012, PTDC/MAT/122897/2010, EXPL/EEI-SII/2556/2013, and by multi-annual funding of CMAF-UL, CBMA-UM and INESC-ID (under the projects PEst-OE/BIA/UI4050/2014 and UID/CEC/50021/2013) provided by FCT-Portugal, and by Fundacao Calouste Gulbenkian through the "Stimulus to Research" program for young researchers. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.info:eu-repo/semantics/publishedVersio

Evolution of Cooperation in Public Goods Games with Stochastic Opting-Out

This paper investigates the evolution of strategic play where players drawn from a finite well-mixed population are offered the opportunity to play in a public goods game. All players accept the offer. However, due to the possibility of unforeseen circumstances, each player has a fixed probability of being unable to participate in the game, unlike similar models which assume voluntary participation. We first study how prescribed stochastic opting-out affects cooperation in finite populations. Moreover, in the model, cooperation is favored by natural selection over both neutral drift and defection if return on investment exceeds a threshold value defined solely by the population size, game size, and a player's probability of opting-out. Ultimately, increasing the probability that each player is unable to fulfill her promise of participating in the public goods game facilitates natural selection of cooperators. We also use adaptive dynamics to study the coevolution of cooperation and opting-out behavior. However, given rare mutations minutely different from the original population, an analysis based on adaptive dynamics suggests that the over time the population will tend towards complete defection and non-participation, and subsequently, from there, participating cooperators will stand a chance to emerge by neutral drift. Nevertheless, increasing the probability of non-participation decreases the rate at which the population tends towards defection when participating. Our work sheds light on understanding how stochastic opting-out emerges in the first place and its role in the evolution of cooperation.Comment: 30 pages, 4 figures. This is one of the student project papers arsing from the Mathematics REU program at Dartmouth 2017 Summer. See https://math.dartmouth.edu/~reu/ for more info. Comments are always welcom

Counterfactual thinking in cooperation dynamics

Counterfactual Thinking is a human cognitive ability studied in a wide variety of domains. It captures the process of reasoning about a past event that did not occur, namely what would have happened had this event occurred, or, otherwise, to reason about an event that did occur but what would ensue had it not. Given the wide cognitive empowerment of counterfactual reasoning in the human individual, the question arises of how the presence of individuals with this capability may improve cooperation in populations of self-regarding individuals. Here we propose a mathematical model, grounded on Evolutionary Game Theory, to examine the population dynamics emerging from the interplay between counterfactual thinking and social learning (i.e., individuals that learn from the actions and success of others) whenever the individuals in the population face a collective dilemma. Our results suggest that counterfactual reasoning fosters coordination in collective action problems occurring in large populations, and has a limited impact on cooperation dilemmas in which coordination is not required. Moreover, we show that a small prevalence of individuals resorting to counterfactual thinking is enough to nudge an entire population towards highly cooperative standards.Comment: 18 page

Reward and punishment in climate change dilemmas

Mitigating climate change effects involves strategic decisions by individuals that may choose to limit their emissions at a cost. Everyone shares the ensuing benefits and thereby individuals can free ride on the effort of others, which may lead to the tragedy of the commons. For this reason, climate action can be conveniently formulated in terms of Public Goods Dilemmas often assuming that a minimum collective effort is required to ensure any benefit, and that decision-making may be contingent on the risk associated with future losses. Here we investigate the impact of reward and punishment in this type of collective endeavors - coined as collective-risk dilemmas - by means of a dynamic, evolutionary approach. We show that rewards (positive incentives) are essential to initiate cooperation, mostly when the perception of risk is low. On the other hand, we find that sanctions (negative incentives) are instrumental to maintain cooperation. Altogether, our results are gratifying, given the a-priori limitations of effectively implementing sanctions in international agreements. Finally, we show that whenever collective action is most challenging to succeed, the best results are obtained when both rewards and sanctions are synergistically combined into a single policy.This research was supported by Fundacao para a Ciencia e Tecnologia (FCT) through grants PTDC/EEISII/5081/2014 and PTDC/MAT/STA/3358/2014 and by multiannual funding of INESC-ID and CBMA (under the projects UID/CEC/50021/2019 and UID/BIA/04050/2013). F.P.S. acknowledges support from the James S. McDonnell Foundation 21st Century Science Initiative in Understanding Dynamic and Multi-scale Systems Postdoctoral Fellowship Award. All authors declare no competing financial or non-financial interests in relation to the work described

Dynamics of Interbacterial Cooperation and Cheating

"Bacterial communities face multiple environmental constraints in their environments. One of the most prevalent ways that bacteria overcome these constraints is the production of public goods. By definition, public goods are compounds that generate benefit for the entire population, producer and other individuals alike. Non-producers of public goods can avoid the cost of production of the public goods but can still benefit from them. When mixed with producers, the energy that non-producers save from not producing the public goods allows them to grow at higher rates than the producers. This can cause the non-producer of the public goods to behave as cheaters, increase in frequency in the overall population and eventually diminish the cooperation and thus the production of the public goods. The lack of public goods production can lead to the drastic reduction of the carrying capacity of the overall population. This phenomenon is defined as the tragedy of the commons in evolutionary biology.(...)"FCG: 1/BD/1

The social evolution of religion : modelling genetic and cultural evolution

Abstract redacte

Social Evolution and Regulatory Architecture of Pseudomonas aeruginosa Quorum Sensing

Cell-cell communication in bacteria is understood to facilitate the coordination of population-wide cooperative behavior in the form of concerted gene expression. The opportunistic pathogen Pseudomonas aeruginosa uses such a communication mechanism to regulate a large group of genes important to virulence strategies in this bacterium. This general mechanism of communication is termed quorum sensing (QS) and restricts activation of target genes to high cell density when cooperation is beneficial. QS in P. aeruginosa, like many Gram-negative Proteobacteria, is mediated through the synthesis of diffusible N-acyl-homoserine lactone (AHL) signals by LuxI-type synthases, and recognition by LuxR-type receptors that function as transcriptional regulators. P. aeruginosa harbors two complete AHL QS synthase receptor pairs termed LasI R and RhlI R. Here we use P. aeruginosa QS as a model system to investigate mechanisms that help maintain cooperative, QS-dependent secretion in the face of non-cooperating cheater mutants, and that define the cell density threshold that triggers the activation of QS target gene expression.We begin with analysis of an in vitro evolution system in which P. aeruginosa must express QS-controlled extracellular proteases in order to grow. In this system, QS-deficient cheater mutants evolve over time. They take advantage of protease production by the QS-proficient wild-type. Curiously, QS-deficient cheaters onlyreach a frequency of about 25% during the duration of the experiment. They do not enrich to levels that would cause a collapse of the population, generally referred to as a “tragedy of the commons”. Genomic sequence analysis revealed a previously unknown mutation in this system in the transcriptional regulator PsdR. Mutations in the gene coding for PsdR derepress growth rate limiting nutrient uptake and metabolism, a non-social adaptation. Combining mutational analysis with phenotypic assays and measurements of relative fitness, we show that rapid fixation of PsdR mutation in evolving populations serves to preserve cooperation and prevent a tragedy of the commons.Next, we focus on the mechanisms that determine the threshold of QS induction in P. aeruginosa. We constructed a set of isogenic mutant strains deficient in one, two, or three anti-activator proteins that serve to delay QS activation: QteE, QscR, and QslA. While these anti-activator proteins are understood to bind LasR and RhlR QS receptors, it is yet unclear why multiple anti-activators are needed, and how they work in concert to achieve the QS threshold. Using phenotypic assays, QS gene activation kinetics, and transcriptomic profiling, we found additive effects in the deletion of multiple anti-activator genes with largely overlapping sets of anti-activator-affected genes. Progressive deletion of anti-activators advances the induction threshold and increases expression levels. Our results suggest some anti-activators may even co-associate with R-proteins in exerting their effect.Together, these studies contribute new mechanistic understanding of how P. aeruginosa uses QS to coordinate cooperative behaviors to specific conditions, and how this cooperative communication system may be safeguarded against social exploitation.Keywords: social interactions, evolution, gene regulation, social evolution, quorum sensin

Co-evolutionary dynamics of collective action with signaling for a quorum.

Collective signaling for a quorum is found in a wide range of organisms that face collective action problems whose successful solution requires the participation of some quorum of the individuals present. These range from humans, to social insects, to bacteria. The mechanisms involved, the quorum required, and the size of the group may vary. Here we address the general question of the evolution of collective signaling at a high level of abstraction. We investigate the evolutionary dynamics of a population engaging in a signaling N-person game theoretic model. Parameter settings allow for loners and cheaters, and for costly or costless signals. We find a rich dynamics, showing how natural selection, operating on a population of individuals endowed with the simplest strategies, is able to evolve a costly signaling system that allows individuals to respond appropriately to different states of Nature. Signaling robustly promotes cooperative collective action, in particular when coordinated action is most needed and difficult to achieve. Two different signaling systems may emerge depending on Nature's most prevalent states