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Microbiomes have profound effects on host fitness, yet we struggle to understand the implications for host ecology. Microbiome influence on host ecology has been investigated using two independent frameworks. Classical ecological theory powerfully represents mechanistic interactions predicting environmental dependence of microbiome effects on host ecology, but these models are notoriously difficult to evaluate empirically. Alternatively, host-microbiome feedback theory represents impacts of microbiome dynamics on host fitness as simple net effects that are easily amenable to experimental evaluation. The feedback framework enabled rapid progress in understanding microbiomes' impacts on plant ecology, and can also be applied to animal hosts. We conceptually integrate these two frameworks by deriving expressions for net feedback in terms of mechanistic model parameters. This generates a precise mapping between net feedback theory and classic population modelling, thereby merging mechanistic understanding with experimental tractability, a necessary step for building a predictive understanding of microbiome influence on host ecology.

The accumulation of knowledge that explains universities’ contributions to innovation and entrepreneurship’s regional eco-systems has mainly adopted a perspective based on technology transfer processes from academia to markets. Alternatively, in this study, we assume the notion of mutualism, based on the biomimetic rationale of eco-system studies that involve bidirectional flows of resources and capabilities to generate interactions and value co-creation among agents. This study theorizes about the interrelation between universities and eco-system actors in two directions: (a) universities fostering and improving eco-systems through their core activities; and (b) eco-system actors shaping capabilities and access to resources for universities. Based on the analysis of five eco-systems in the state of Sao Paulo, Brazil, our results underscore the existence of mutualism in the relationships established between universities and eco-system agents. The findings also highlighted implications related to the coordination of policies and the need for strategic management practices in mutualistic interactions.

Funder: Leibniz Gemeinschaft, The domestication of plants and the origin of agricultural societies has been the focus of much theoretical discussion on why, how, when, and where these happened. The 'when' and 'where' have been substantially addressed by different branches of archaeology, thanks to advances in methodology and the broadening of the geographical and chronological scope of evidence. However, the 'why' and 'how' have lagged behind, holding on to relatively old models with limited explanatory power. Armed with the evidence now available, we can return to theory by revisiting the mechanisms allegedly involved, disentangling their connection to the diversity of trajectories, and identifying the weight and role of the parameters involved. We present the Human-Plant Coevolution (HPC) model, which represents the dynamics of coevolution between a human and a plant population. The model consists of an ecological positive feedback system (mutualism), which can be reinforced by positive evolutionary feedback (coevolution). The model formulation is the result of wiring together relatively simple simulation models of population ecology and evolution, through a computational implementation in R. The HPC model captures a variety of potential scenarios, though which conditions are linked to the degree and timing of population change and the intensity of selective pressures. Our results confirm that the possible trajectories leading to neolithisation are diverse and involve multiple factors. However, simulations also show how some of those factors are entangled, what are their effects on human and plant populations under different conditions, and what might be the main causes fostering agriculture and domestication.

This paper is concerned with the stationary problem for a diffusive Lotka-Volterra predator-prey-mutualist model with a protection zone under homogeneous Neumann boundary conditions. Compared with the case where the mutualist is absent in [12] , this paper aims to reveal the effects of mutualism coefficients α and β on the existence, number and stability of steady states. It turns out that when α is large, the model has at most one steady state and it is stable (if it exists); however existence of multiple steady states is examined for large β, moreover asymptotic profiles of steady states are established as β tends to infinity.

Wildlife value orientations (WVOs) are used to address human–wildlife conflicts by developing value-framed messaging. However, little is known about whether WVOs (i.e., mutualism, domination) are useful in distance-related wildlife safety communication strategies. This study explores the predictive ability of mutualism and domination value orientations on study participants’ levels of agreement with distance-related safety messages. Distance-related wildlife safety messages were crafted to appeal to the four WVO typologies (i.e., traditionalist, mutualist, pluralist, and distanced). Undergraduate students were asked to rate their levels of agreement with a series of distance-related messages. Confirmatory factor analyses were used to create domination and mutualism dimension scores. Multiple regressions predicted levels of agreement with each of the messages from domination and mutualism. Study results indicated that in this sample of undergraduate student participants, only mutualism values predicted distance-related wildlife safety message agreement. This information can be used to help frame communications about distance-related wildlife issues.

This paper considers a two-patch mutualism system derived from exchange of resource for resource, where the obligate mutualist can diffuse asymmetrically between patches. First, we give a complete analysis on dynamics of the system without diffusion, which exhibit how resource production of the obligate mutualist leads to its survival/extinction. Using monotone dynamics theory, we show global stability of a positive equilibrium in the three-dimensional system with diffusion. A novel finding of this work is that the obligate species' final abundance is explicitly expressed as a function of the diffusion rate and asymmetry, which demonstrates precise mechanisms by which the diffusion and asymmetry lead to the abundance higher than if non-diffusing, even though the facultative species declines. It is shown that for a fixed diffusion rate, intermediate asymmetry is favorable while extremely large asymmetry is unfavorable; For a fixed asymmetry, small diffusion is favorable while extremely large asymmetry is unfavorable. Initial densities of the species are also shown to be important in species' persistence and abundance. Numerical simulations confirm and extend our results.

The fragility of the postcolonial Zimbabwean state and concomitant failed governance has opened crevices through which alternative forms of self-organising and social formation are emerging. In the...

In times of water shortage, it becomes increasingly relevant for policymakers to understand the existing relationships between different types of water use, so as to encourage efficient water management. This article makes use of yearly data on agricultural, industrial, and household water use in the Balkan countries of Bulgaria, Romania, and Serbia. It does so to identify the potential interactions among these three categories of water use. Using a deterministic model based on differential equations, we provide an analysis of the interactions among these different sectors of water use for the period between 2008 and 2017. Results show that interactions among these different categories do not remain constant over periods of time, either across or within the countries analysed. We find that, for most countries, industrial and household water uses are more likely to be characterised by mutualism and competition, instead of a predator-prey relationship. Agricultural water use, on the other hand, takes on the role of predator against the other two.

We perform a stability analysis on a discrete analogue of a known, continuous model of mutualism. We illustrate how the introduction of delays affects the asymptotic stability of the system's positive nontrivial equilibrium point. In the second part of the paper we explore the insights that the model can provide when it is used in relation to interacting financial markets. We also note the limitations of such an approach.

Fungus-growing attine ants are under constant threat from fungal pathogens such as the specialized mycoparasite Escovopsis, which uses combined physical and chemical attack strategies to prey on the fungal gardens of the ants. In defence, some species assemble protective microbiomes on their exoskeletons that contain antimicrobial-producing Actinobacteria. Underlying this network of mutualistic and antagonistic interactions are an array of chemical signals. Escovopsis weberi produces the shearinine terpene-indole alkaloids, which affect ant behaviour, diketopiperazines to combat defensive bacteria, and other small molecules that inhibit the fungal cultivar. Pseudonocardia and Streptomyces mutualist bacteria produce depsipeptide and polyene macrolide antifungals active against Escovopsis spp. The ant nest metabolome is further complicated by competition between defensive bacteria, which produce antibacterials active against even closely related species., Highlights • Specialist fungal pathogens attack the nests of fungus-growing ants. • Ants form mutualistic relationships with defensive actinomycete bacteria. • Specialised metabolites underpin these mutualistic and antagonistic interactions.

Eusociality represents an extreme form of social behavior characterized by a reproductive division of labor. Eusociality necessarily evolved through kin selection, which requires interactions among related individuals. However, many eusocial taxa also show cooperation between non-kin groups, challenging the idea that cooperative actions should only occur among relatives. This review explores the causes and consequences of non-kin cooperation in ants. Ants display a diversity of behaviors that lead to non-kin cooperation within and between species. These interactions occur among both reproductive and non-reproductive individuals. The proximate and ultimate mechanisms leading to non-kin cooperative interactions differ substantially depending on the biotic and abiotic environment. We end this review with directions for future research and suggest that the investigation of non-kin cooperative actions provides insight into processes leading to social evolution.

Fungal secondary metabolites (FSMs) are capable of manipulating plant community dynamics by inhibiting or facilitating the establishment of co-habitating organisms. Although production of FSMs is not crucial for survival of the producer, their absence can indirectly impair growth and/or niche competition of these fungi on the plant. The presence of FSMs with no obvious consequence on the fitness of the producer leaves questions regarding ecological impact. This review investigates how fungi employ FSMs as a platform to mediate fungal-fungal, fungal-bacterial and fungal-animal interactions associated with the plant community. We discuss how the biological function of FSMs may indirectly benefit the producer by altering the dynamics of surrounding organisms. We introduce several instances where FSMs influence antagonistic- or alliance-driven interactions. Part of our aim is to decipher the meaning of the FSM 'language' as it is widely noted to impact the surrounding community. Here, we highlight the contribution of FSMs to plant-associated interaction networks that affect the host either broadly or in ways that may have previously been unclear.

It is true that film as media can reflect a lot significant values in society, one of them is tolerance. It is crucial to discuss about tolerance because more societies have become diverse. Therefore, exploring tolerance from films can be fascinating and useful. By using American superhero films (Fantastic 4 (2005), Fantastic 4: Rise of the Silver Surfer (2007), and Black Panther (2018) to depict the how tolerance is represented, this study is useful to enhance understanding of tolerance which has always become one of important vales to have. By applying Hall’s theory of representation, this study exposes two essential points. Tolerance must be conceptualized by incorporating mutualism, understanding, and peace. Besides, that tolerance shown on American superhero movies is represented through the portrait of race and gender.

Fungal pathogenicity toward insects has independently evolved several times, resulting in specialist and generalist pathogens, some of whom have maintained aspects of their previous lifestyles. Being able to grow as an endophyte (engaging in a mutualistic interaction with plants) or saprophyte (recycling nutrients back into the environment), the generalist (broad-host-range) fungus Beauveria bassiana does not need to rely on insect hosts to complete its life cycle. The diverse lifestyles of this fungus, saprophyte, pathogen, and symbiont, provide a unique system, with available genetic tools, to examine host-pathogen interactions, plant-fungus mutualistic relationships, and fungal development. This commentary highlights overlooked pathogenic and mutualistic aspects of B. bassiana that assist this fungus in shifting along the saprobe/parasite/mutualist continuum. Addressing these knowledge gaps and scrutinizing valuable players driving such a spectrum of ecological interactions will enrich our knowledge of fundamental environmental microbiology and help develop new approaches to pest control and sustainable farming.

Value orientations can predict attitudes and possibly behaviors. Wildlife value orientations (WVOs) are useful constructs for predicting differences in attitudes among segments of the public towards issues in the wildlife domain. We carried out face-to-face interviews with a representative sample of the Greek population (n = 2392) to investigate two basic WVOs, domination and mutualism and the four WVO types that result from their combination: traditionalist (high domination, low mutualism), mutualist (high mutualism, low domination), distanced (low mutualism, low domination) and pluralist (high mutualism, high domination), and how they relate to sociodemographics. Based on basic WVOs, the Greek population was predominantly mutualism-oriented. The analysis of WVO types also revealed that mutualists were the most abundant (41.0%) followed by the distanced (31.1%). Traditionalists (17.9%) and pluralists (10.0%) occupied smaller proportions of the population. Younger individuals were more mutualist-oriented, while older individuals (&gt, 35 years old) were more traditionalist and distanced-oriented. Females were more mutualist than males, the latter being more traditionalist. Those with higher education were more mutualist and less traditionalist and distanced than those with lower education. Pet owners were more mutualist and less distanced than non-pet owners. WVO types did not vary with current residence. The produced knowledge would inform about differences in WVOs among segments of the public and would be therefore useful for implementing successful wildlife conservation and management plans.

Understanding why individuals carry out behaviours that benefit others, especially genetically unrelated others, has been a major undertaking in many fields and particularly in biology. Here, we focus on the cooperation literature from natural populations and present the benefits of a social network approach in terms of how it can help to identify and understand factors that influence the maintenance and spread of cooperation, but are not easily captured when solely considering independent dyadic interactions. We describe how various routes to cooperation can be tested within the social network framework. Applying the social network approach to data from natural populations can help to uncover the evolutionary and ecological pressures that lead to differences in cooperation and other social processes.

Plants due to their non-motile nature rely heavily on mutualistic interactions to obtain resources and carry out services. One key mutualism is the plant-microbial mutualism in which a plant trades away carbon to a microbial partner for nutrients like nitrogen and phosphorous. Plants show much variation in the use of this partnership from the individual level to entire lineages depending upon ecological, evolutionary, and environmental context. We sought to determine how this context dependency could result in the promotion, exclusion, or coexistence of the microbial mutualism by seeing if and when the partnership provided a competitive advantage to the plant. To that end, we created a simple 2 × 2 evolutionary game in which plants could either be a mutualist and pair with a microbe or a non-mutualist and forgo the partnership. This model included nutrients freely available to the plant, nutrients obtained only through mutualism with microbes, the cost of producing roots, the cost of trade with microbes, and the size of the local competitive neighborhood. Not surprisingly, we found that mutualism could offer a competitive advantage if its net benefit was positive. Coexistence between strategies is possible though due to competition between mutualists over the microbially obtained nutrient. In addition, the greater the size of the local competitive neighborhood, the greater the region of coexistence but only at the expense of mutualist fixation (non-mutualist fixation was unaffected). Our model, though simple, shows that plants can gain a competitive advantage from using a mutualism depending upon the context and points to basic experiments that can be done to verify the results.

During the last 15 years, the number of institutions for collective action has risen significantly in Europe, and especially in the Netherlands. Where market- or government arrangements are deemed insufficients, goods and services are provided locally in energy, care, and food coops. Of particular interest is the revival of self-organized insurance in mutual insurance associations (mutuals), which require cooperation and trust under uncertainty. Members share risk and pay monthly contributions to support each other without knowing whether they ever need support, how many others need support, and whether these others remain a member to repay the favor in the future. Uncertainty severely complicates collective action and makes cooperation more fragile. At any moment members can decide to withdraw when support requests are too high. Why do some risk-sharing initiatives succeed, while others don't? To what extent does success depend on the individuals involved or the initiative's social and institutional properties? This dissertation answers these questions using a multidisciplinary approach. The results of agent-based simulations, abstract experiments and surveys among members of a Dutch risk-sharing organization are integrated to derive multi-faceted evidence on success factors for collective action and uncover institutional opportunities for optimizing success of mutuals.

This article explains how 19th-century radical republicans answered the following question: how is it possible to be free in a social order that fosters economic dependence on others? I focus on the writings of a group of French thinkers called the solidarists who advocated “liberty organized for everyone.” Mutualism and social right were two components of the solidarist strategy for limiting domination in commercial/industrial society. While the doctrine of mutualism was rooted in pre-industrial artisan culture, social right was a novel idea that built on Durkheim’s analysis of the division of labour. In this article, I describe the main features of the solidarist account: solidarity, social property, quasi-contractual debt, and restorative justice. Classical republicanism was deeply concerned with citizen participation and the balance between popular and elite power, but 19th-century radical republicans thought that these goals must be approached differently in market societies in which enormous power is exercised outside the state. The solidarists cautiously embraced the state as a mechanism for regulating the market in order to ensure equal liberty. Social right and mutualism were also conceived as ways of limiting the centralization of state power.

1. Ecological stoichiometry theory was applied to investigate how a consumer contends with an extreme elemental mismatch between its food and its body via symbiotic facilitation. 2. The beetle Dendroctonus brevicomis LeConte develops in bark, a substrate extremely low in nitrogen (N) and phosphorus (P). Its survival there depends on interactions with mutualist and antagonist fungi. 3. This study found that mutualists transfer N and P from sapwood and phloem into bark, where beetles feed, whereas the antagonist moves these elements only to phloem, resulting in starvation of the insect. However, even with mutualists, N and P concentrations remained low in bark, resulting in low N and extremely low P concentrations in the beetle. 4. The N:P ratios found in D. brevicomis larvae were the highest thus far reported for beetles and among the highest for insects and invertebrates. This suggests that the beetle has evolved additional, nutrient‐sparing adaptations.

A three-species population system under a facultative mutualistic relationship of one of the species is studied. The considered interactions are as follows: facultative between the first species and the second species, obligatory mutualism between the second species and the first one, and the third species is a predator of the first species. For this purpose, we extend the model proposed by Morozov et al., originally used to describe obligatory mutualism, to consider obligatory and facultative mutualism and prove that under adequately selected parameters this system produces a spatial patchy spread of populations or continuous wave fronts. Since the analytical treatment of a three-species model is often prohibitive, we first analyze the interaction between two mutualist species without diffusion and without the presence of the predator. Some parameters are fixed in the bistable regime of the mutualistic species to further consider the influence of the third species. The remaining parameters are then selected to produce patchy patterns under different mortality rates. Finally, the equations of the final three-species system are numerically solved to test the influence of different initial conditions in the formation of patchy populations. It is confirmed that the velocity and the profile of a traveling front are independent on the initial conditions. Our approach opens the way to study more general biological situations.

Theory suggests that the direct transmission of beneficial endosymbionts (mutualists) from parents to offspring (vertical transmission) in animal hosts is advantageous and evolutionarily stable, yet many host species instead acquire their symbionts from the environment (horizontal acquisition). An outstanding question in marine biology is why some scleractinian corals do not provision their eggs and larvae with the endosymbiotic dinoflagellates that are necessary for a juvenile's ultimate survival. We tested whether the acquisition of photosynthetic endosymbionts (family Symbiodiniaceae) during the planktonic larval stage was advantageous, as is widely assumed, in the ecologically important and threatened Caribbean reef-building coral Orbicella faveolata. Following larval acquisition, similar changes occurred in host energetic lipid use and gene expression regardless of whether their symbionts were photosynthesizing, suggesting the symbionts did not provide the energetic benefit characteristic of the mutualism in adults. Larvae that acquired photosymbionts isolated from conspecific adults on their natal reef exhibited a reduction in swimming, which may interfere with their ability to find suitable settlement substrate, and also a decrease in survival. Larvae exposed to two cultured algal species did not exhibit differences in survival, but decreased their swimming activity in response to one species. We conclude that acquiring photosymbionts during the larval stage confers no advantages and can in fact be disadvantageous to this coral host. The timing of symbiont acquisition appears to be a critical component of a host's life history strategy and overall reproductive fitness, and this timing itself appears to be under selective pressure.

Obligate mutualist interactions appear to be ubiquitous in nature but cannot be described by the simple models that have been so effective for developing the theory of other population interactions...

This paper studies global dynamics of a class of plant–pollinator–robber systems, in which plant is the resource while the pollinator and nectar robber are two competing consumers. The nectar robber is a parasite of plant while the pollinator is the mutualist. Based on the competition–parasitism–mutualism interactions, we established a plant–pollinator–robber model by nectar-mediated consumer–resource theory. By complete analysis on the model, we demonstrate necessary and sufficient conditions for the principle of competitive exclusion to hold and give the global dynamical behavior of the three species in the first octant, in which a three-dimensional saddle–node bifurcation is exhibited. It is shown that pollination–mutualisms promote survival of the nectar robber, the invasion of nectar robber would mean extinction of both the pollinator and the nectar robber itself, while the pollinator (resp. robber) can drive the robber (resp. pollinator) into extinction. Initial population densities of the species are exhibited to play a role in persistence of the systems. This analysis demonstrates mechanisms by which the pollinator and nectar robber can stably coexist, which is observed in real situations.

Hit by the economic and political crisis, young people in Italy face increased labor precarity and the disillusionment derived from the disappearance of the radical Left from the parliamentary arena. In the Italian context, economic hardship, the decrease of resources available for collective action, and the weakened mobilizing capacity that traditional mass organizations (such as trade unions and political parties) retained in the first decade of the 2000s brought about a general decline in intensity and visibility of street protests, leading to an apparent retreat of activism to the local level of action. Although the crisis had a negative impact on collective action, evidence reveals that more creative and less visible forms of societal and political commitment were adopted by young generations in these years. This article explores how the Italian youth in times of crisis engaged actively in alternative and unconventional forms of political commitment aimed at re-appropriating space, free time, and access to leisure, mainly by means of mutualistic practices. Based on data from qualitative semistructured interviews with key informants and activists, this article sheds light on recreational activism, adopted as a political practice by the Italian youth active in counter-cultural spaces, nowadays at the forefront of the struggle to oppose the commodification of free time and leisure.

Abundant diversity of microbial communities existing in nature follows the rule of coexistence demonstrating interspecies and interkingdom interactions for their proliferation. These communities exhibit highly complex and interwoven web of metabolic communications. They also perform division of labor managing their metabolic load for the survival of different co-inhabitants of that area. These microbial consortia are involved in various interactions such as mutualism and syntropy, commensalism, and antagonistic behavior as a part of their struggle for existence. Due to their unique properties of division of labor, diversified metabolic capacities, and ability of co-survival, microbial consortia can be exploited for approaches applied for maintaining sustainability of the environment. They can be utilized in agricultural practices that can reduce the use of chemical fertilizers and pesticides. Microbial mixed cultures also have potential for waste management and bioremediation. Additionally, they can prove to be an attractive alternative as a source of biofuel and bioenergy generation.

While beneficial plant-microbe interactions are common in nature, direct evidence for the evolution of bacterial mutualism is scarce. Here we use experimental evolution to causally show that initially plant-antagonistic Pseudomonas protegens bacteria evolve into mutualists in the rhizosphere of Arabidopsis thaliana within six plant growth cycles (6 months). This evolutionary transition is accompanied with increased mutualist fitness via two mechanisms: (i) improved competitiveness for root exudates and (ii) enhanced tolerance to the plant-secreted antimicrobial scopoletin whose production is regulated by transcription factor MYB72. Crucially, these mutualistic adaptations are coupled with reduced phytotoxicity, enhanced transcription of MYB72 in roots, and a positive effect on plant growth. Genetically, mutualism is associated with diverse mutations in the GacS/GacA two-component regulator system, which confers high fitness benefits only in the presence of plants. Together, our results show that rhizosphere bacteria can rapidly evolve along the parasitism-mutualism continuum at an agriculturally relevant evolutionary timescale., Beneficial plant-microbe interactions are common in nature, but direct evidence for the evolution of mutualism is scarce. Here, Li et al. experimentally evolve a rhizospheric bacterium and find that it can evolve into a mutualist on a relatively short timescale.

SummaryEven though beneficial plant-microbe interactions are commonly observed in nature, direct evidence for the evolution of bacterial mutualism in the rhizosphere remains elusive. Here we use experimental evolution to causally show that initially plant-antagonistic Pseudomonas protegens bacterium evolves into mutualists in the rhizosphere of Arabidopsis thaliana within six plant growth cycles (6 months). This evolutionary transition was accompanied with increased mutualist fitness via two mechanisms: i) improved competitiveness for root exudates and ii) enhanced capacity for activating the root-specific transcription factor gene MYB72, which triggers the production of plant-secreted scopoletin antimicrobial for which the mutualists evolved relatively higher tolerance to. Genetically, mutualism was predominantly associated with different mutations in the GacS/GacA two-component regulator system, which conferred high fitness benefits only in the presence of plants. Together, our results show that bacteria can rapidly evolve along the parasitism-mutualism continuum in the plant rhizosphere at an agriculturally relevant evolutionary timescale.

International audience; In the last few decades, microbial inoculants have been used as organic fertilizers worldwide. Among the most widely used commercial products are arbuscular mycorrhizal (AM) fungi, as these fungi can associate with a variety of crops. Despite the potential benefits for soil quality and crop yield associated with AM fungal colonization, experiments assessing the persistence of the fungi in the field have yielded inconsistent results. Additionally, it is not yet clear whether or not the introduction of commercial inoculants could lead to changes to the resident fungal community, and eventually to invasion of the commercial products with a possible displacement of resident species. Here we use a partial differential equation model to assess the potential biodiversity risks and productivity benefits deriving from inoculation. We study the impact of AM fungal inoculation on the resident fungal community and on plant growth at a landscape scale. We determine how inoculant persistence and spread is affected by its competition with resident fungal species, by its mutualist quality, and by fungal dispersal. Our findings suggest that the increase in fungal abundance due to inoculation always leads to a short-term increase in host productivity, regardless of inoculant identity. However, the use of strongly competing inoculants constitutes a biodiversity risk, and may result in the invasion of low quality mutualists.

Microorganisms produce materials leaked from the cell which are beneficial for themselves and their neighbors. We modeled the situation when cells can produce different costly secretions which increase the carrying capacity of the population. Strains that lose the function of producing one or more secretions avoid the cost of production and can exhaust the producers. However, secreting substances provides a private benefit for the producers in a density-dependent way. We developed a model to examine the outcome of the selection among different type of producer strains from the non-producer strain to the partial producers, to the full producer one. We were particularly interested in circumstances under which selection maintains partners that produce complementary secreted materials thus forming an interdependent mutualistic interaction.We show that interdependent mutualism is selected under broad range of conditions if private benefit decreases with density. Selection frequently causes the coexistence of more and less generalist cooperative strains, thus cooperation and exploitation co-occur. Interdependent mutual-ism is evolved under more specific circumstances if private benefit increases with density and these general observations are valid in a well-mixed and in a structured deme model. We show that the applied population structure supports cooperation in general, which, depending on the level of private benefit and intensity of mixing helps either the specialist or the generalist cooperators.

Interactions between plants and soil fungi and bacteria are ubiquitous and have large effects on individual plant fitness. However, the degree to which spatial variation in soil microbial communities modulates plant species' distributions remains largely untested. Using the California native plant Clarkia xantiana ssp. xantiana we paired glasshouse and field reciprocal transplants of plant populations and soils to test whether plant-microbe interactions affect the plant's geographic range limit and whether there is local adaptation between plants and soil microbe communities. In the field and glasshouse, one of the two range interior inocula had a positive effect on plant fitness. In the field, this benefit was especially pronounced at the range edge and beyond, suggesting possible mutualist limitation. In the glasshouse, soil inocula from beyond-range tended to increase plant growth, suggesting microbial enemy release beyond the range margin. Amplicon sequencing revealed stark variation in microbial communities across the range boundary. Plants dispersing beyond their range limit are likely to encounter novel microbial communities. In C. x. xantiana, our results suggest that range expansion may be facilitated by fewer pathogens, but could also be hindered by a lack of mutualists. Both negative and positive plant-microbe interactions will likely affect contemporary range shifts.

We want to understand how children get so much better at certain cognitive abilities like reading, writing, and problem solving as they get older. To better understand this, we followed hundreds of children across a period of years, to see how abilities like problem solving and vocabulary changed over time. We found that having good vocabulary to start with made children’s problem solving develop more quickly. It also worked the other way around: being better at problem solving meant children were quicker to learn new words. In other words, each cognitive ability may help other abilities develop. This idea is called mutualism. We were very excited by this discovery, because it can help us understand how children get better at things they never practice directly, and how teachers can better help children who find certain school topics more challenging.

The most common intracellular symbiont on the planet— Wolbachia pipientis —is infamous largely for the reproductive manipulations induced in its host. However, more recent evidence suggests that this bacterium may also serve as a nutritional mutualist in certain host backgrounds and for certain metabolites. We performed a large-scale analysis of conserved gene content across all sequenced Wolbachia genomes to infer potential nutrients made by these symbionts.

Metacommunity membership is influenced by habitat availability and trophic requirements. However, for multitrophic symbiont communities that are closely associated with host plants, symbionts and hosts may additionally influence each other affecting membership criteria in novel ways. For example, failure of beneficial services from a symbiont could elicit a response from the host that impacts the entire community. Understanding such host-symbiont feedback effects on symbiont community membership can be crucial for understanding symbiont community structure and function. We investigate membership for a multitrophic insect symbiont community where symbionts colonize host inflorescences during specific developmental stages termed colonization windows. Inflorescences are host-derived organs and serve as habitat microcosms. Symbionts exhibit a diversity of interactions ranging from mutualism to parasitism. Hosts exhibit immediate feedback by aborting inflorescences not pollinated by mutualistic symbionts and habitats are consequently lost for all other symbiont species. Using relevant empirically measured microcosm parameters, we simulate symbiont dispersal from and colonization of other host inflorescences. We vary host densities and symbiont colonization window lengths, and track the persistence of each symbiont species in the metacommunity based on the temporal availability of the resource and the trophic position of the symbiont. Since the persistence of the microcosm habitat is dictated by pollination performed by the mutualist, the mutualist fares better than all other symbionts. For prey, the length of colonization windows was positively related with colonization success and symbiont persistence. For predators, the cumulative length of the colonization windows of their prey dictated their success; diet breadth or prey colonization success did not influence the persistence of predators. Predators also had a greater host-plant density requirement than prey for persistence in the community. These results offer valuable insights into host density requirements for maintaining symbionts, and have implications for multitrophic symbiont community stability. Synthesis: Factors influencing symbiont community membership can be unique when host-symbiont feedback impacts host microcosm development. Special constraints can govern symbiont community membership, function and structure and symbiont persistence in such metacommunities.

The nature and the strength of plant–frugivore interactions often vary along an antagonism–mutualism continuum and are highly influenced by the local ecological context (e.g. level of environmental disturbances). However, little is known concerning how the local ecological setting where plant–frugivore interactions take place affects the seed dispersal effectiveness (SDE) and, eventually, plant recruitment. This knowledge gap relates to the scarcity of empirical investigations on individual-based plant–frugivore networks. We assessed whether the assembly of interaction modes (antagonist and mutualist) of the dwarf palm Chamaerops humilis (Arecaeae) affect the individual and the population level SDE in two Mediterranean sites differing in perturbation levels. We analysed the frequency distribution of interaction typologies and test its relationship with variation among individual palms in SDE. Additionally, we document how variation in interaction motif frequency (e.g. overrepresented interaction typologies) relates to changes in the SDE landscape of both disturbed study sites. We found that the interaction typologies of individual palms and its frugivores did not occur randomly. In a more complex landscape, interactions were more diverse and less dominated by simpler typologies, which may increase the stability of the plant–disperser interaction over the long term. We demonstrate that plants that interact with a more complex assemblage of frugivores, including both mutualistic and antagonistic partners, had the highest probability of recruitment. We found that the highly variable SDE among individual palms resulted from a few interaction modes occurring at higher than expected frequencies. We suggest this may be a reasonably frequent situation in diversified frugivore assemblages with a high heterogeneity of functional effects among mutualistic and antagonistic partners.

Plant roots are associated with a diverse microbial community that consists of antagonistic, commensal and mutualistic organisms. While beneficial plant-microbe interactions are important for plant performance, direct evidence for the evolution of rhizosphere mutualism remains elusive. Here we experimentally show that initially plant-antagonistic Pseudomonas protegens bacterium can rapidly evolve into a mutualist in the rhizosphere of Arabidopsis thaliana only within six plant growth cycles (6 months). Using an in vivo experimental evolution system, we observed that P. protegens rapidly diversified into distinct phenotypes, with some having clearly positive effects on the plant performance. Crucially, this evolution of plant facilitation was also accompanied with increased bacterial fitness indicative of a mutualistic interaction. At the genetic level, P. protegens mutualism was associated with mutations in the GacS/GacA two-component global regulator system, which is known to affect several aspects of bacterial physiology including carbon metabolism, host-microbe signalling, and downregulation of phytotoxic secondary metabolites. At the phenotypic level, the evolution of mutualism could be explained via two mechanisms: improved competition for root exudates and enhanced capacity for activating the root-specific transcription factor gene MYB72, which is essential for the production and excretion of the antimicrobial scopoletin for which the mutualists evolved enhanced tolerance. Together, these results show that plant-bacteria mutualism can rapidly evolve at an agriculturally relevant evolutionary timescale in the rhizosphere.

Explaining the evolution of cooperation represents one of the greatest challenges in both evolutionary biology and social science. However, asymmetrical interaction, as one typical characteristic of cooperative system, has not been sufficiently considered in the existing literature for the evolution of cooperation. Incorporating the asymmetry in the strategy sets, we here construct an asymmetric game model with the so-called carrot-stick strategy, which is a mixed strategy of reward and punishment. Based on mathematical analyses, it is unveiled that this asymmetric interaction can lower the dilemma of cooperation: the dominant players and recipient players might coexist through cycle frequency. Further analysis shows that the multi-equilibria are possible, which depend on the payoff parameters and the initial conditions. That is to say, by setting up different values of the cost-to-benefit, the punishment-to-benefit, and the reward-to-benefit, we can recover three basic evolutionary dynamics of systems: dominance; bistability and coexistence. These theoretical observations are consistent with existing empirical outcomes that asymmetric sanction or reward of host species might solve the conflicts between the actors in the fig-fig wasp mutualism or in the cleaner fish-client mutualism. It is thus suggested that this asymmetric strategy setup may shed new light into the solution of social dilemmas.

Research on mutualism seeks to explain how cooperation can be maintained when uncooperative mutants co-occur with cooperative kin. Gains and losses of the gene modules required for cooperation punctuate symbiont phylogenies and drive lifestyle transitions between cooperative symbionts and uncooperative free-living lineages over evolutionary time. Yet whether uncooperative symbionts commonly evolve from within cooperative symbiont populations or from within distantly related lineages with antagonistic or free-living lifestyles (i.e., third-party mutualism exploiters or parasites), remains controversial. We use genomic data to show that genotypes that differ in the presence or absence of large islands of symbiosis genes are common within a single wild recombining population of Mesorhizobium symbionts isolated from host tissues and are an important source of standing heritable variation in cooperation in this population. In a focal population of Mesorhizobium, uncooperative variants that lack a symbiosis island segregate at 16% frequency in nodules, and genome size and symbiosis gene number are positively correlated with cooperation. This finding contrasts with the genomic architecture of variation in cooperation in other symbiont populations isolated from host tissues in which the islands of genes underlying cooperation are ubiquitous and variation in cooperation is primarily driven by allelic substitution and individual gene gain and loss events. Our study demonstrates that uncooperative mutants within mutualist populations can comprise a significant component of genetic variation in nature, providing biological rationale for models and experiments that seek to explain the maintenance of mutualism in the face of non-cooperators.

Due to poor technology and lack of proper skills in mineral processing techniques, a greater percentage (about 70%) of gold is lost to the tailings stream in artisanal and small-scale gold mining (ASGM). These tailings, in the last decade, have become a major source of revenue for some large-scale mining (LSM) companies in Ghana because they have advanced technologies to optimize recovery. This paper examines the tailings trade between ASGM and LSM companies in Ghana and determines their associated relationships. It also informs policy decisions regarding gold mining in Ghana. Field visits were made to licensed ASGM sites in the Tarkwa Mining District where the trade is mostly practiced to obtain first-hand information and conduct interviews with diggers. Results indicate that both ASGM operators and LSM companies derive revenue from the tailings trade, exhibiting a relationship that could be described as mutualistic. Based on the tailings price determination, the symbiotic relationship is described as parasitic because the tailings pricing process is largely controlled by the LSM companies to the detriment of the ASGM operators. As a result of the environmental dangers posed by the tailings trade, the interdependency could equally be described as parasitic since both the ASGM operators and the LSM companies benefit to the detriment of the natural ecosystem. It was also observed that while some stakeholders attempt to criminalize the tailings trade, there is presently no law or regulation that prohibits such trade in the Ghanaian mining industry.

Economic studies have shown that there are two types of regulation schemes which can be considered as a vital part of today's global economy: self-regulation enforced by self-regulation organizations to govern industry practices, and government regulation which is considered as another scheme to sustain corporate adherence. An outstanding problem of particular interest is to understand quantitatively the role of these regulation schemes in evolutionary dynamics. Typically, punishment usually occurs for enforcement of regulations. Taking into account both types of punishments to curve the regulations, we develop a game model where six evolutionary situations with corresponding combinations of strategies are considered. Furthermore, a semi-analytical method is developed to allow us to give an accurate estimations of the boundaries between the phases of full defection and nondefection. We find that, associated with the evolutionary dynamics, for infinite well-mixed population, the mix of both punishments performs better than one punishment alone in promoting public cooperation, but for networked population the cooperator-driven punishment turns out to be a better choice. We also uncover monotonous facilitating effects of synergy effect, punishment fine and feedback sensitivity on the public cooperation for infinite well-mixed population. Conversely, for networked population an optimal intermediate range of feedback sensitivity is needed to best promote punishers' populations. Overall, networked structure is overall more favorable for punishers and further for public cooperation, because of both network reciprocity and mutualism between punishers and cooperators who do not punish defectors., 29 pages, 23 figures

In this article, I will identify two key normative principles at the core of Robert L. Simon’s mutualist theory of sport, namely, the respect-for-the-opponent principle and the idea that sport is a...

Mutualism describes the biological phenomenon where two or more species are reciprocally beneficial, regardless of their ecological intimacy or evolutionary history. Classic theory shows that mutualistic benefit must be relatively weak, or else it overpowers the stabilizing influence of intraspecific competition and leads to unrealistic, unbounded population growth. Interestingly, the conclusion that strong positive interactions lead to runaway population growth is strongly grounded in the behavior of a single model. This model—the Lotka–Volterra competition model with a sign change to generate mutualism rather than competition between species—assumes logistic growth of each species plus a linear interaction term to represent the mutualism. While it is commonly held that the linear interaction term is to blame for the model's unrealistic behavior, we show here that a linear mutualism added to a θ-logistic model of population growth can prevent unbounded growth. We find that when density dependence is decelerating, the benefit of mutualism at equilibrium is greater than when density dependence is accelerating. Although there is a greater benefit, however, decelerating density dependence tends to destabilize populations whereas accelerating density dependence is always stable. We interpret these findings tentatively, but with promise for the understanding of the population ecology of mutualism by generating several predictions relating growth rates of mutualist populations and the strength of mutualistic interaction.

Mechanisms that allow for the coexistence of two competing species that share a trophic level can be broadly divided into those that prevent competitive exclusion of one species within a local area, and those that allow for coexistence only at a regional level. While the presence of aphid‐tending ants can change the distribution of aphids among host plants, the role of mutualistic ants has not been fully explored to understand coexistence of multiple aphid species in a community. The tansy plant (Tanacetum vulgare) hosts three common and specialized aphid species, with only one being tended by ants. Often, these aphids species will not coexist on the same plant but will coexist across multiple plant hosts in a field. In this study, we aim to understand how interactions with mutualistic ants and predators affect the coexistence of multiple species of aphid herbivores on tansy. We show that the presence of ants drives community assembly at the level of individual plant, that is, the local community, by favoring one ant‐tended species, Metopeurum fuscoviride, while preying on the untended Macrosiphoniella tanacetaria and, to a lesser extent, Uroleucon tanaceti. Competitive hierarchies without ants were very different from those with ants. At the regional level, multiple tansy plants provide a habitat across which all aphid species can coexist at the larger spatial scale, while being competitively excluded at the local scale. In this case, ant mutualist‐dependent reversal of the competitive hierarchy can drive community dynamics in a plant–aphid system.

Where positive externalities are structural inevitabilities of particular behaviors and strategies (e.g. “Black Queen (BQ) functions”), stable commensalism is both possible and likely even between individuals who would otherwise be in close competition, and the coexistence thus stabilized generates opportunity for the eventual development of mutual and collective benefit. Here we review examples of BQ functions in animal behavior, both in the natural world and in human economies, with a focus on how these functions encourage the evolution of specialization and division of labor. The non-human examples we consider range from microbial systems to vertebrate communities while the human examples consider economic agents ranging from foraging societies to superpowers. With these examples, we discuss four classes of BQ functions: (i) functions that protect against harmful things in the environment; (ii) functions that provide products with value added relative to their constituent parts; (iii) functions that provide structures that can be utilized by other organisms; and (iv) functions that yield information. We also explore a set of examples where BQ-stabilized commensal relationships developed into two-way exchange relationships in human systems: (i) the ancient mutualism between humans and dogs, (ii) the division of labor in human societies between sexes and age groups, and (iii) the dominance of Silicon Valley over other regional technology centers. We conclude that BQ functions are an underappreciated motivator of markets and communities and suggest future experimental evolution research encouraged by our perspective.

In this paper, I defend a general theory of competition and contrast it with a corresponding general theory of cooperation. I then use this analysis to critique mutualism. Building on the work of A...