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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.

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.

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.

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 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.

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.

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.

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.

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.

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.

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.

The ecology of the early environment - including microbial diversity, nutrition, nature, social interactions and the totality of exposures in the wider "exposome" - have life-long implications for all aspects of health and resilience. In particular, the emergence of "microbiome science" provides new evidence for vital relationships between biodiversity and health at every level. New perspectives of ecological interdependence connect personal and planetary health; the human health crisis cannot be separated from the social, political and economic "ecosystems" otherwise driving dysbiosis (from its etymological root, "life in distress") at every level. Adverse changes in macroscale ecology - of food systems, lifestyle behaviours, socioeconomic disadvantage and environmental degradation - all impact the microbial systems sitting at the foundations of all ecosystems. In particular, changes in the function and composition of the human-associated microbiome have been implicated in the mounting global burden of noncommunicable diseases (NCDs), exacerbating inflammation and metabolic dysregulation through multiple pathways across the lifespan. This "dysbiotic drift" (adverse shifts in ecology at all scales) underscores the need for ecological approaches aimed at restoring symbiosis, balance and mutualism. While there is promise with supplement-based strategies (e.g. probiotics, prebiotics), it is essential to focus on upstream factors implicated in dysbiosis, including the health of wider environments, lifestyle, nature relatedness, and the social policies and practices which can facilitate or inhibit dysbiotic drift. This also calls for ambitious integrative approaches which not only define these interconnections, but also capitalize on them to create novel, collaborative and mutualistic solutions to our vast interdependent global challenges.L’écologie de l’environnement précoce - comprenant diversité microbienne, nutrition, nature, interactions sociales et totalité des expositions du large « exposome » - a des implications tout au long de la vie pour tous les aspects de la santé et de la résilience. En particulier, l’émergence de « la science du microbiome » fournit de nouvelles preuves pour les relations vitales entre biodiversité et santé à tous les niveaux. De nouvelles perspectives d’interdépendance écologique connectent la santé personnelle et planétaire ; la crise de la santé humaine ne peut être séparée des écosystèmes économique, politique et social à moins de mener à la dysbiose (de son origine étymologique « vie en péril ») à tous les niveaux. Les changements indésirables de l’écologie à grande échelle - systèmes alimentaires, comportement de style de vie, désavantages socio-économiques et dégradation environnementale - impactent tous les systèmes microbiens siégeant à la base de tous les écosystèmes. En particulier, les changements de fonction et de composition du microbiome associé à l’homme ont été impliqués dans l’augmentation de la charge globale des maladies non transmissibles (NCDs), exacerbant l’inflammation et la dérégulation du métabolisme à travers de multiples voies au cours de la vie. Cette « dérive de dysbiose » (dérives indésirables de l’écologie à tous les niveaux) sous-estime le besoin des approches écologiques objectivant la restauration symbiose, balance et mutualisme. Alors que des stratégies supplémentaires sont prometteuses (ex : probiotiques, prébiotiques), il est essentiel de focaliser sur des facteurs en amont impliqués dans la dysbiose, comprenant : santé d’environnements plus larges, style de vie, nature de la parenté, et pratiques sociales, qui peuvent faciliter ou inhiber la dérive de dysbiose. Ceci appel aussi des approches qui ne définissent pas seulement ces interconnections mais aussi capitalisent sur elles pur créer des solutions nouvelles, collaboratives et mutualistes pour nos vastes défis globaux interdépendants.La ecología del medio ambiente temprano -incluida la diversidad microbiana, la nutrición, la naturaleza, las interacciones sociales y la totalidad de las exposiciones en toda la amplitud del “exposoma”- tiene implicaciones de por vida para todos los aspectos de la salud y la resiliencia. En particular, el surgimiento de la “ciencia del microbioma” proporciona nueva evidencia de las relaciones vitales entre la biodiversidad y la salud en todos los niveles. Nuevas perspectivas de interdependencia ecológica conectan la salud personal y planetaria; la crisis de la salud humana no puede separarse de los “ecosistemas” sociales, políticos y económicos que de otro modo conducen a la disbiosis (de su raíz etimológica, “vida alterada”) en todos los niveles. Los cambios adversos en la ecología a macroescala (de los sistemas alimentarios, los comportamientos de estilo de vida, las desventajas socioeconómicas y la degradación ambiental) tienen un impacto en los sistemas microbianos que se encuentran en los cimientos de todos los ecosistemas. En particular, los cambios en la función y composición del microbioma asociado a los seres humanos se han visto implicados en la creciente carga mundial de enfermedades no transmisibles (ENT), que exacerban la inflamación y la disregulación metabólica a través de múltiples vías a lo largo de la vida. Esta "deriva disbiótica" (cambios adversos en la ecología a todas las escalas) subraya la necesidad de enfoques ecológicos destinados a restaurar la simbiosis, el equilibrio y el mutualismo. Si bien es prometedor con las estrategias basadas en suplementos (por ejemplo, probióticos, prebióticos), es esencial centrarse en los factores anteriores implicados en la disbiosis, incluida la salud de entornos más amplios, el estilo de vida, la relación con la naturaleza y las políticas y prácticas sociales que pueden facilitar o inhibir la deriva disbiótica. Esto también requiere enfoques integradores ambiciosos que no solo definan estas interconexiones, sino que también las aprovechen para crear soluciones novedosas, colaborativas y mutualistas para nuestros vastos desafíos globales interdependientes.Die Ökologie der frühen Entwicklung - inklusive mikrobieller Diversität, Ernährung, Natur, sozialer Interaktion und der Gesamtheit der Exponierung im weiteren „Exposom“ - hat lebenslange Implikationen für alle Aspekte von Gesundheit und Resilienz. Im Speziellen stellt das Auftreten des „Mikrobiom Wissenschaft“ eine neue Evidenz für vitale Beziehungen zwischen der Biodiversität und der Gesundheit auf jedem Level dar. Neue Perspektiven ökologischer Interdependenz verknüpfen persönliche Gesundheit mit der des Planeten; die Humane Gesundheitskrise kann nicht von den sozialen, politischen und ökonomischen „Ökosystemen“ separiert werden, weil sonst die Dysbiose (von ihrer etymologischen Wurzel, „Leben in Qualen“) auf jedem Level vorangetrieben würde. Negative Veränderungen in der Makroskala der Ökologie - von Lebensmittelsystemen, Verhalten im Lebensstil, sozioökonomische Nachteile und Umweltverfall - haben alle eine Auswirkung auf die mikrobiellen Systeme, die sich an der Basis aller Ökosysteme befinden. Man geht davon aus, dass vor allem Veränderungen der Funktion und der Zusammensetzung des mit dem Menschen assoziierten Mikrobioms bei der zunehmenden globalen Belastung von nicht-kommunizierbaren Erkrankungen (NCDs) eine Rolle spielen, was die Entzündung und die metabolische Dysregulation durch multiple Stoffwechselwege im Verlauf einer Lebensspanne verschlimmert. Die „dysbiotische Abweichung“ (ungünstige Veränderungen der Ökologie auf allen Ebenen) unterstreicht die Notwendigkeit für ökologische Herangehensweisen, die darauf abzielen die Symbiose, Balance und Mutualismus wiederherzustellen. Während es vielversprechende Supplement-basierte Strategien (z.B. Probiotika, Präbiotika) gibt, ist es essenziell, sich auf die steigenden Faktoren zu konzentrieren, die bei der Dysbiose eine Rolle spielen. Diese inkludieren die Gesundheit der weiteren Umwelt, den Lebensstil, die Naturverbundenheit und die Sozialpolitik und Praktiken, die eine dysbiotische Abweichung möglich machen können. Das ruft ebenso nach ambitionierten integrativen Herangehensweisen, die nicht nur diese Querverbindungen definieren, sondern auch aus ihnen Nutzen ziehen, um neue, kollaborative und gemeinsame Lösungen für unsere riesigen voneinander abhängigen globalen Herausforderungen zu kreieren.微生物の多様性、栄養、自然、社会的相互作用、そして「エクスポソーム」と呼ばれる広範囲の曝露を含む幼少期の環境の生態は、健康と回復力のすべての側面に生涯にわたる影響を及ぼす。特に、「マイクロバイオーム科学」の登場は、あらゆるレベルでの生物多様性と健康との重要な関係を示す新たなエビデンスを提供する。生態学的相互依存という新しい視点は、個人と地球の健康を結びつける。それゆえに、人間の健康危機は、社会的、政治的、経済的な「生態系」から切り離すことはできず、あらゆるレベルで「ディスバイオーシス」を引き起こす (語源は「苦悩する生命」) 。マクロスケールの生態系における有害な変化 (食料システム、生活習慣、社会経済的不利益、環境悪化など) は、すべての生態系の基盤となる微生物システムに影響を与える。特に、ヒトに関連するマイクロバイオームの機能と組成の変化は、非伝染性疾患 (NCD) の世界的な負担の増大に関係しており、生涯にわたる複数の経路を通じて炎症および代謝異常を悪化させている。このような「dysbiotic drift」 (あらゆる規模での生態系の悪影響) は、共生、バランス、相互作用を回復させることを目的とした生態学的アプローチの必要性を強調している。プロバイオティクスやプレバイオティクスなどのサプリメントに基づく戦略には期待が寄せられているが、より広い環境の健全性、ライフスタイル、自然との関連性、dysbiotic driftを促進または抑制する社会政策や慣行など、ディスバイオーシスに関与する上流の要因に焦点を当てることが不可欠である。また、これらの相互関係を明確にするだけでなく、相互に依存する地球規模の膨大な課題に対して、斬新で協力的かつ相互主義的な解決策を生み出すために、これらを活用する野心的な統合的アプローチが求められている。.早期环境的生态学--包括微生物多样性、营养、自然、社会互动和更广泛的“暴露组”中的全部暴露--对健康和复原力的所有方面都有终生的影响。特别是“微生物组科学”的出现为生物多样性与健康在每个层面上的重要关系提供了新的证据。生态相互依存的新观点将个人和全球健康联系起来; 人类健康危机不能脱离社会、政治和经济“生态系统”, 否则在每个层面上都会造成微生态失调 (来自其词源“生活在困境中”) 。宏观生态学的不利变化--食物系统、生活方式行为、社会经济劣势和环境退化--都会影响位于所有生态系统基础上的微生物系统。特别是, 人类相关微生物组的功能和组成的变化导致非传染性疾病(NCDs)日益增加的全球负担, 通过整个生命周期的多种途径加剧炎症和代谢失调。这种“共生漂移” (所有尺度上生态的不利转变) 强调了需要旨在恢复共生、平衡和互惠的生态方法。虽然基于营养添加剂的策略 (例如益生菌、益生元) 带来希望, 但必须关注与微生态失调有关的上游因素, 包括更广泛环境、生活方式、自然相关性, 以及社交策略和实践的健康, 可促进或抑制微生态失调漂移。这还要求采取雄心勃勃的综合办法, 不仅确定这些相互联系, 而且利用这些相互联系, 为我们巨大的相互依存的全球挑战创造新颖、合作和互惠的解决办法。.A ecologia do ambiente inicial - incluindo diversidade microbiana, nutrição, natureza, interações sociais e a totalidade das exposições no “exposome” mais amplo - tem implicações ao longo da vida para todos os aspectos da saúde e resiliência. Em particular, o surgimento da “ciência do microbioma” fornece novas evidências para relações vitais entre a biodiversidade e a saúde em todos os níveis. Novas perspectivas de interdependência ecológica conectam a saúde pessoal e planetária; a crise da saúde humana não pode ser separada dos “ecossistemas” social, político e econômico, levando à disbiose (de sua raiz etimológica, “vida em perigo”) em todos os níveis. Mudanças adversas na ecologia da macroescala - de sistemas alimentares, hábitos de vida, desvantagem socioeconômica e degradação ambiental - impactam os sistemas microbianos que estão na base de todos os ecossistemas. Em particular, as mudanças na função e na composição do microbioma associado ao ser humano têm sido implicadas no aumento da carga global de doenças não comunicáveis (DNCs), exacerbando a inflamação e a desregulação metabólica por meio de várias vias ao longo da vida. Esta “deriva disbiótica” (mudanças adversas na ecologia em todas as escalas) ressalta a necessidade de abordagens ecológicas destinadas a restaurar a simbiose, o equilíbrio e o mutualismo. Embora as estratégias baseadas em suplementos (por exemplo, probióticos, prebióticos) sejam uma grande promessa, é essencial focar nos fatores desencadeadores relacionados à disbiose, incluindo a saúde de forma geral, estilo de vida, relacionamento com a natureza e as políticas e práticas sociais que podem facilitar ou inibir a deriva disbiótica. Isso também exige abordagens integrativas ambiciosas que não apenas definam essas interconexões, mas também as capitalizem para criar soluções novas, colaborativas e mutualísticas para nossos desafios globais vastos e interdependentes.

Plants attract mutualistic animals by offering a reward of nectar. Specifically, floral nectar (FN) is produced to attract pollinators, whereas extrafloral nectar (EFN) mediates indirect defenses through the attraction of mutualist predatory insects to limit herbivory. Nearly 90% of all plant species, including 75% of domesticated crops, benefit from animal-mediated pollination, which is largely facilitated by FN. Moreover, EFN represents one of the few defense mechanisms for which stable effects on plant health and fitness have been demonstrated in multiple systems, and thus plays a crucial role in the resistance phenotype of plants producing it. In spite of its central role in plant-animal interactions, the molecular events involved in the development of both floral and extrafloral nectaries (the glands that produce nectar), as well as the synthesis and secretion of the nectar itself, have been poorly understood until recently. This review will cover major recent developments in the understanding of (1) nectar chemistry and its role in plant-mutualist interactions, (2) the structure and development of nectaries, (3) nectar production, and (4) its regulation by phytohormones.

Following defaunation, the loss of interactions with mutualists such as pollinators or seed dispersers may be compensated through increased interactions with remaining mutualists, ameliorating the negative cascading impacts on biodiversity. Alternatively, remaining mutualists may respond to altered competition by reducing the breadth or intensity of their interactions, exacerbating negative impacts on biodiversity. Despite the importance of these responses for our understanding of the dynamics of mutualistic networks and their response to global change, the mechanism and magnitude of interaction compensation within real mutualistic networks remains largely unknown. We examined differences in mutualistic interactions between frugivores and fruiting plants in two island ecosystems possessing an intact or disrupted seed dispersal network. We determined how changes in the abundance and behavior of remaining seed dispersers either increased mutualistic interactions (contributing to “interaction compensation”) or decreased interactions (causing an “interaction deficit”) in the disrupted network. We found a “rich-get-richer” response in the disrupted network, where remaining frugivores favored the plant species with highest interaction frequency, a dynamic that worsened the interaction deficit among plant species with low interaction frequency. Only one of five plant species experienced compensation and the other four had significant interaction deficits, with interaction frequencies 56-95% lower in the disrupted network. These results do not provide support for the strong compensating mechanisms assumed in theoretical network models, suggesting that existing network models underestimate the prevalence of cascading mutualism disruption after defaunation. This work supports a mutualist biodiversity-ecosystem functioning relationship, highlighting the importance of mutualist diversity for sustaining diverse and resilient ecosystems. This article is protected by copyright. All rights reserved.

The effects of spatial heterogeneity in negative biological interactions on individual performance and species diversity have been studied extensively. However, little is known about the respective effects involving positive biological interactions, including the symbiosis between plants and ectomycorrhizal (EM) fungi. Using a greenhouse bioassay, we explored how spatial heterogeneity of natural soil inoculum influences the performance of pine seedlings and composition of their root-associated EM fungi. When the inoculum was homogenously distributed, a single EM fungal taxon dominated the roots of most pine seedlings, reducing the diversity of EM fungi at the treatment level, while substantially improving pine seedling performance. In contrast, clumped inoculum allowed the proliferation of several different EM fungi, increasing the overall EM fungal diversity. The most dominant EM fungal taxon detected in the homogeneous treatment was also a highly beneficial mutualist, implying that the trade-off between competitive ability and mutualistic capacity does not always exist.

Establishing a horizontally transmitted mutualism is a critical step for many organisms, particularly when an individual can engage with only one partner over its lifetime. Ant foundresses shed their wings before they start to lay eggs, which makes host choice particularly critical for plant-ants that exclusively colonize myrmecophytes. Volatile organic compounds (VOCs) can indicate the identity and physiological condition of an individual and frequently serve as signals or cues that facilitate partner choice. Thus, we hypothesized that obligate plant-ants use VOCs to determine the quality of potential host plants. Indeed, winged females of the plant-ant, Pseudomyrmex ferrugineus, used plant odours to identify high-quality acacia hosts among different species and among individuals of the same species. The VOC blend of a branch was related to reward production and, interestingly, the least attractive blend contained the highest number of compounds. Although only seven different VOCs could be detected in the blend of the high-reward host species, the low-reward host emitted 13 different compounds, among which (S)-(-)-limonene and β-linalool were the dominant ones. Complementing the odour of the high-reward host with (S)-(-)-limonene, β-linalool or α-terpinene reduced its attractiveness. Strikingly, these compounds inhibited bacterial pathogens of the host plant. Synthesis. Plant-ants can use host plant odours that contain resistance-related VOCs to judge on host quality, likely because of negative crosstalk between direct resistance to disease and investment in ant-mediated defence. VOCs can serve as cues that provide reliable information for partner choice, particularly when their emission results from a physiological process that causally relates to the quality of an individual as a mutualist.

The Agricultural Revolution and plant domestication in the Near East (among its components) have fascinated generations of scholars. Here, we narrate the history of ideas underlying plant domestication research since the late 19th century. Biological and cultural perspectives are presented through two prevailing models: one views plant domestication as a protracted, unconscious evolutionary mutualistic (noncentric) process. The second advocates a punctuated, knowledge-based human initiative (centric). We scrutinize the research landscape while assessing the underlying evolutionary and cultural mechanisms. A parsimony measure indicates that the punctuated-centric view better accords with archaeological records, and the geobotany and biology of the species, and requires fewer assumptions. The protracted alternative requires many assumptions, does not account for legume biology, fails to distinguish domestication from postdomestication changes, and, therefore, is less parsimonious.

Many models of mutualism have been proposed and studied individually. In this paper, we develop a general class of models of facultative mutualism that covers many of such published models. Using mild assumptions on the growth and self-limiting functions, we establish necessary and sufficient conditions on the boundedness of model solutions and prove the global stability of a unique coexistence equilibrium whenever it exists. These results allow for a greater flexibility in the way each mutualist species can be modelled and avoid the need to analyse any single model of mutualism in isolation. Our generalization also allows each of the mutualists to be subject to a weak Allee effect. Moreover, we find that if one of the interacting species is subject to a strong Allee effect, then the mutualism can overcome it and cause a unique coexistence equilibrium to be globally stable.

Coexistence of plants depends on their competition for common resources and indirect interactions mediated by shared exploiters or mutualists. These interactions are driven either by changes in animal abundance (density-mediated interactions, e.g., apparent competition), or by changes in animal preferences for plants (behaviorally-mediated interactions). This article studies effects of behaviorally-mediated interactions on two plant population dynamics and animal preference dynamics when animal densities are fixed. Animals can be either adaptive exploiters or adaptive mutualists (e.g., herbivores or pollinators) that maximize their fitness. Analysis of the model shows that adaptive animal preferences for plants can lead to multiple outcomes of plant coexistence with different levels of specialization or generalism for the mediator animal species. In particular, exploiter generalism promotes plant coexistence even when inter-specific competition is too strong to make plant coexistence possible without exploiters, and mutualist specialization promotes plant coexistence at alternative stable states when plant inter-specific competition is weak. Introducing a new concept of generalized isoclines allows us to fully analyze the model with respect to the strength of competitive interactions between plants (weak or strong), and the type of interaction between plants and animals (exploitation or mutualism). Keywords: behaviorally-mediated interactions, competition for preference, differential inclusion, generalized isocline, switching, sliding and repelling regimes., Comment: 33 pages, 9 figures

Metacommunity membership is influenced by habitat availability and trophic requirements. However, for multitrophic horizontally transmitted symbiont communities that are closely associated with hosts, symbiont–host interactions may affect membership criteria in novel ways. For example, failure of beneficial services from symbionts could influence the host, and in turn, the entire community. Understanding such host–symbiont feedback effects on symbiont community membership, symbiont community structure, and function is important for understanding if host–symbiont communities are fundamentally different from more traditional ecological communities. We investigate the membership criteria for a multitrophic insect symbiont community that colonizes host inflorescences at specific developmental stages termed colonization windows. The inflorescences serve as microcosm habitats. Symbionts exhibit a range of interactions from mutualism to parasitism. Hosts exhibit feedback by aborting inflorescences not pollinated by mutualistic symbionts. Habitats are consequently lost for all other symbiont species in such host-derived organs whose development is mutualist-dependent. Using empirical measurements to characterize inflorescence development, we simulate symbiont dispersal colonization across hosts. We vary host densities and lengths of symbiont colonization windows, and track the persistence of each symbiont species in the metacommunity based on its trophic requirements and resource availability within the microcosm. Since the persistence of the microcosm habitat is dictated by pollination performed by the mutualist, the mutualist fared better than all other symbionts. The length of symbiont colonization windows was positively related with colonization success and symbiont persistence. The cumulative length of the colonization windows of prey dictated predator success; diet breadth or prey colonization success did not influence predator persistence. Predators also had a greater host-plant density requirement than prey for persistence in the community. These results offer valuable insights into host densities required for maintaining symbionts, and have implications for multitrophic symbiont community stability. Special constraints can govern symbiont community membership, function and structure and symbiont persistence when host–symbiont feedback impacts host microcosm development.

Most wood-boring insects compete with wood decaying basidiomycetes for woody biomass. One clade of ambrosia beetles gained access to rotten wood – an abundant resource unsuitable to most wood-boring insects – by evolving a farming-like mutualism with a white rot polypore. Here we show the mutualist of Ambrosiodmus/Ambrosiophilus, the polypore Flavodon ambrosius, is superior in lignocellulolytic capacity compared to Ascomycota ambrosia fungi and other white rot Basidiomycota. This mutualism facilitated the evolution of large, long-lived, communal colonies with overlapping generations and egg-laying by pre-dispersal progeny females. F. ambrosius resembles other white rot Polyporales in that it causes significant weight loss in wood decay assays and strong polyphenol oxidase reactions, indicative of lignin-modifying enzymes. The symbiosis is asymmetrical: there are many species of Ambrosiodmus and Ambrosiophilus but all use a single known species of Flavodon, which determines the ecological strategy of the entire insect clade.

Mutualism is ubiquitous in nature and plays an integral role in most communities. To predict the eco-evolutionary dynamics of mutualism it is critical to extend classic pair-wise analysis to include additional species. We investigated the effect of adding a third species to a pair-wise mutualism in a spatially structured environment. We tested the hypotheses that selection for costly excretions in a focal population (i) decreases when an exploiter is added (ii) increases when a third mutualist is added relative to the pair-wise scenario. We assayed the selection acting on Salmonella enterica when it exchanges methionine for carbon in an obligate mutualism with an auxotrophic Escherichia coli. A third bacterium, Methylobacterium extorquens, was then added and acted either as an exploiter of the carbon or third obligate mutualist depending on the nitrogen source. In the tripartite mutualism M. extorquens provided nitrogen to the other species. Contrary to our expectations, adding an exploiter increased selection for methionine excretion in S. enterica. Conversely, selection for cooperation was lower in the tripartite mutualism relative to the pair-wise system. Genome-scale metabolic models helped identify the mechanisms underlying these changes in selection. Our results highlight the utility of connecting metabolic mechanisms and eco-evolutionary dynamics.

The interaction between yucca plants and yucca moths has been one of the focal model systems investigated in the study of pollination mutualism and coevolution, especially in terms of understanding the prevention of overexploitation by mutualist partners. Yuccas have the ability to assess the number of eggs placed by pollinators into their ovaries, and can preferentially abort those flowers that would have many moth larvae consuming yucca seeds. Previous phylogenetic research identified a rapid radiation of moth species that corresponded with shifts in the interaction with their host plants. These shifts led to the evolution of moth species that circumvent the egg detection method used by yuccas to limit seed damage. In particular, some pollinator species deposit their eggs so that they are undetectable by the plants, whereas other species are ‘cheaters’ that have lost the ability to pollinate, yet deposit eggs into developing fruit rather than flowers. The evolution of these new species happened so quickly that the phylogeny of the moths has remained unresolved despite repeated attempts with standard Sanger sequencing of mtDNA loci and AFLP marker generation. Here, we use extensive analyses of RAD-seq data to determine the phylogenetic relationships among yucca moth species. The results provide a robust phylogenetic framework that identifies the evolutionary relationships among shifts in egg-laying strategies, as well as determining the closest pollinating relatives to the cheater species. Based on the obtained phylogeny, a shift in egg-laying strategy that avoided the overexploitation regulatory mechanism used by yucca plants was a precursor for the evolution of two species with cheating behaviour.

Large-scale change in human values and associated behavior change is believed by some to be the ultimate solution to achieve global biodiversity conservation. Yet little is known about the dynamics of values. We contribute to this area of inquiry by examining the trajectory of values affecting views of wildlife in North America. Using data from a 19-state study in the United States and global data from the Schwartz Value Survey, we explored questions of value persistence and change and the nature of attitudinal responses regarding wildlife conservation issues. We found support, based on subjects' ancestry, for the supposition that domination is a prevalent American value orientation toward wildlife that has origins in European Judeo-Christian traditions. Independent of that effect, we also found indications of change. Modernization is contributing to a shift from domination to mutualism value orientations, which is fostering attitudes less centered on human interests and seemingly more consistent with a biocentric philosophy. Our findings suggest that if value shift could be achieved in a purposeful way, then significant and widespread behavior change believed necessary for long-term conservation success may indeed be possible. In particular, greater emphasis on mutualism values may help provide the context for more collaborative approaches to support future conservation efforts. However, given the societal forces at play, it is not at all clear that human-engineered value shift is tenable. Instead of developing strategies aimed at altering values, it may be more productive to create strategies that recognize and work within the boundaries of existing values. Whereas values appear to be in a period of flux, it will be difficult to predict future trends without a better understanding of value formation and shift, particularly under conditions of rapid social-ecological change.

We model the mutualism interactions between gobies and shrimp based on recent experimental work on the shrimp Alpheus floridans and the facultative and obligate gobies Ctenogobius saepepallens and Nes longus in the Bahamas. We show that the model is consistent with observations, and suggest that obligate mutualism may favour rapid speciation in gobies due to their restricted spatial range. We calculate the resilience of the goby-shrimp systems to evaluate the robustness of the mutualist interactions to parameter choices. While experimental evidence has noted the ubiquity of obligation in gobies, our theoretical investigation predicts the ubiquity of facultative mutualism in shrimp despite the many obligate mutualism strategies open to them. Future experimental work might be usefully directed at evaluating the ubiquity of facultative versus obligate interactions of shrimp in goby - shrimp mutualist populations, and examining whether facultative and obligate strategies are correlated with food availability.

Mutualism, interspecific cooperation that yields reciprocal benefits, can promote species coexistence, enhancing biodiversity. As a specific form of mutualism, cross-feeding, where each of two mutualists produces a resource the other one needs, has been broadly studied. However, few theoretical studies have examined competition between cross-feeding mutualists and cheaters, who do not synthesize resources themselves. In this paper we study a model with two mutualists, a cheater, two micronutrients that are synthesized and exchanged by the mutualists, and one macronutrient that is only from external supply. We investigate the coexistence of the species in the framework of resource competition theory. In particular, we examine the effect of the mutualists’ synthesis rates on their coexistence. In the absence of cheaters, multiple stable states occur if the synthesis rates are high, and higher synthesis rates increase the possibility that mutualists coexist. However, when the cheater is present, higher synthesis rates promote invasion by the cheater: If the cheater is superior on all three resources, it will either persist with at most one mutualist or even trigger extinction of all three species; if the cheater is only superior on the macronutrient, both mutualists may still coexist with the cheater. Our results provide a framework for further study on more complex mutualistic networks and real microbial communities.

Species interactions and coexistence are often dependent upon environmental conditions. When two cross-feeding bacteria exchange essential nutrients, the addition of a cross-fed nutrient to the environment can release one species from its dependence on the other. Previous studies suggest that continued coexistence depends on relative growth rates: coexistence is maintained if the slower-growing species is released from its dependence on the other, but if the faster-growing species is released, the slower-growing species will be lost (a hypothesis that we call 'feed the faster grower' or FFG). Using invasion-from-rare experiments with two reciprocally cross-feeding bacteria, genome-scale metabolic modelling and classical ecological models, we explored the potential for coexistence when one cross-feeder became independent. We found that whether nutrient addition shifted an interaction from mutualism to commensalism or parasitism depended on whether the nutrient that limited total growth was required by one or both species. Parasitism resulted when both species required the growth-limiting resource. Importantly, coexistence was only lost when the interaction became parasitism, and the obligate species had a slower growth rate. Under these restricted conditions, the FFG hypothesis applied. Our results contribute to a mechanistic understanding of how resources can be manipulated to alter interactions and coexistence in microbial communities.

Human activities have substantially increased atmospheric nitrogen (N) deposition in ecosystems worldwide, often leading to higher plant quality for herbivores and greater herbivory. Predators frequently suppress herbivores and indirectly benefit plants via “trophic cascades”, and the strength of these interactions can also depend on N availability. However, the evidence for N deposition effects on cascades primarily comes from studies of high‐level N deposition. Most terrestrial ecosystems currently receive elevated, but low‐level N deposition, and it is unclear whether this subtle N enrichment has any effect on cascades. Here, I asked whether low‐level N deposition alters a trophic cascade from black bears to plants in Colorado. In this ecological network, bears indirectly benefit plants by consuming ants and suppressing positive effects of ants on herbivores. Using a three year N enrichment experiment, I assessed changes in this cascade by measuring plant and arthropod responses to simulated N deposition, bear damage to ant nests, and the presence of mutualist herbivores and ants. I found that low‐level N enrichment and bears had interacting effects on plant reproduction. In ambient N conditions, bears indirectly increased plant reproduction by causing ant nests to become inactive and suppressing positive ant effects on herbivores that were detrimental for plants. Yet, bear‐induced ant nest inactivity had no effect on plant reproduction in N‐enriched conditions. When N was added, ants had greater positive effects on herbivores, but herbivores had weak effects on plants, potentially because plants were more resistant to herbivores. Ultimately, the results indicate that N enrichment strengthened resource control of the community and weakened plant–herbivore interactions and the cascade from bears to plants. This study suggests that common rates of low‐level N deposition are changing the strength of trophic cascades and may have already altered resource versus consumer control of ecological community structure in many ecosystems.

The abiotic environment drives species abundances and distributions both directly and indirectly through effects on multi-trophic species interactions. However, few studies have documented the individual and combined consequences of these direct and indirect effects. We studied an ant-tended aphid along an elevational gradient, where lower elevations were more arid. Hypotheses of stronger species interactions at lower elevations and a greater sensitivity of higher trophic levels to climate led us to predict increased top-down control of aphids by natural enemies (third trophic level) but even stronger protection from mutualist ants (fourth trophic level) with increasing aridity. As a result, we predicted that mutualism strength and aphid abundance would increase with aridity. We documented patterns of aphid abundance and tested for both the direct and multi-trophic indirect effects of aridity on aphid performance. To do so, we used both observational and manipulative methods across two years in replicate high- and low-elevation valleys, where summer temperatures decreased by 3.7°C and precipitation increased by 27 mm/mo from low to high elevations. Aphid colonies were 75% larger in the most (vs. least) arid sites, and this was best explained by changes in interactions with predators and ants. Aphids were unaffected by the direct effects of the abiotic environment or its indirect effects via host plant quality. In contrast, natural enemy effects increased with aridity; under ant exclusion, natural enemies had no effect on aphids in the least arid sites but depressed colony growth by 252% in the most arid sites. Ant activity also increased with aridity, with ants discovering more aphid colonies and experimental baits and allocating more foragers per aphid, although there was no effect of aridity on ant abundance or community composition. Correspondingly, the mutualist services provided by ants increased with aridity; ants provided no benefits to aphids in the least arid sites but doubled colony growth in the most arid sites. In summary, an elevational cline in herbivore abundance was driven by a monotonic increase in trophic-level sensitivity to aridity. These findings illustrate that predicting species responses to climate change will require a multi-trophic perspective.

Differences in temperature ranges and optima among poikilothermic partners in symbioses can have profound effects on their interactions and stability. In this study, we investigated how the two mutualist mycangial fungi (Ceratocystiopsis brevicomi and Entomocorticium sp. B) associated with the western pine beetle, Dendroctonus brevicomis, respond to temperature in vitro. Little variability in growth rate at the various temperatures tested occurred among isolates of C. brevicomi either within or among sites. In contrast, E. sp. B exhibited highly variable responses to mid-range temperatures among sites and within some sites, and, unlike C. brevicomi, grew not at all or only very poorly at the highest and lowest temperatures tested. This variability affected both optimal temperature and maximum growth rate. The high variability in response to some temperatures among isolates of E. sp. B in some populations indicates that the ability to capture spatial and nutritional resources can vary greatly within this species which may have considerable impact on the outcome of both inter- and intra-specific competition among the fungi within trees and the short- and long-term dynamics of the fungi with the host beetle.

UNLABELLED • PREMISE OF THE STUDY Multiple mutualist effects (MMEs) are common in nature, yet we lack a predictive understanding of how two mutualists on the same host will influence each other and whether these effects will be positive or negative. Leguminous plants maintain root symbioses with two nutritional mutualists: rhizobia that fix atmospheric nitrogen and arbuscular mycorrhizal fungi (AMF) that increase phosphorus uptake. Both symbionts receive plant carbon, and host genetic networks that regulate colonization are partially shared by both symbioses; whether these factors generate trade-offs or facilitation between rhizobial and AMF symbionts of legumes is not well known.• METHODS We evaluated host allocation to each symbiont in three settings. First, in situ in a remnant prairie, then in a greenhouse experiment with multiple plant populations, and finally under manipulated rhizobium densities in the greenhouse.• KEY RESULTS In the remnant prairie, rhizobium nodule number and colonization of AMF were positively correlated, and plants with increased nodule number had higher fitness in the field, generating indirect selection on the colonization of AMF. In the greenhouse experiment, allocation to each symbiont was genetically variable among populations, with some suggestion that rhizobium and AMF colonization are positively genetically correlated. Finally, increasing the number of rhizobia in the soil decreased AMF colonization.• CONCLUSIONS Our results suggest that trade-offs between plant colonization by rhizobia and AMF are context dependent and might not be common under field conditions, but that physiological and/or genetic drivers couple these two symbioses in nature.

The Sirex woodwasp, Sirex noctilio, and its fungal mutualist, Amylostereum areolatum, together constitute one of the most damaging invasive pests of pine. Despite a century of research and well-established management programs, control remains unpredictable and spread continues to new areas. Variable success in managing this pest has been influenced by complex invasion patterns, the multilayered nature of biological interactions, the varying local ecologies, and microevolutionary population processes in both the biocontrol organisms and in the wasps. Recent research findings are challenging the historical perspectives on methods to manage the Sirex woodwasp, calling for management programs to incorporate the variable local dynamics affecting this pest complex. In this regard, the Sirex woodwasp provides a superb model to illustrate the need for a different approach to develop efficient and sustainable management tools to deal with the growing and global nature of pest invasions in forests and plantations.

Pollination interactions are common, and their maintenance is critical for many food crops upon which human populations depend. Pollination is a mutualism interaction; together with predation and competition, mutualism makes up the triumvirate of fundamental interactions that control population dynamics. Here we examine pollination interactions (nectar reward for gamete transport service) using a simple heuristic model similar to the Lotka–Volterra models that have underpinned our understanding of predation and competition so effectively since the 1920s. We use a genetic algorithm to simulate the eco-evolutionary interactions of the plant and pollinator populations and examine the distributions of the parameter values and zero isoclines to infer the relative ubiquity of the various eco-evolutionary outcomes possible in the model. Our results suggest that trade-offs between costs and benefits for the pollinator may be a key component of obligate pollination systems in achieving adaptive success creating and stably occupying mutualist niches.

Climate change can influence the abundance of insect herbivores through direct and indirect mechanisms. In this study, we evaluated multitrophic drivers of herbivore abundance for an aphid species (Aphis helianthi) in a subalpine food web consisting of a host plant (Ligusticum porteri), mutualist ants and predatory lygus bugs (Lygus spp.). We used a model-selection approach to determine which climate and host plant cues best predict year-to-year variation in insect phenology and abundance observed over 6 years. We complemented this observational study with experiments that determined how elevated temperature interacts with (1) host plant phenology and (2) the ant-aphid mutualism to determine aphid abundance. We found date of snowmelt to be the best predictor of yearly abundance of aphid and lygus bug abundance but the direction of this effect differed. Aphids achieved lower abundances in early snowmelt years likely due to increased abundance of lygus bug predators in these years. Elevating temperature of L. porteri flowering stalks reduced their quality as hosts for aphid populations. However, warming aphid colonies on host plants of similar quality increased population growth rates. Importantly, this effect was apparent even in the absence of ants. While we observed fewer ants tending colonies at elevated temperatures, these colonies also had reduced numbers of lygus bug predators. This suggests that mutualism with ants becomes less significant as temperature increases, which contrasts other ant-hemipteran systems. Our observational and experimental results show the importance of multitrophic species interactions for predicting the effect of climate change on the abundances of herbivores.

Evidence accumulates about the role of arbuscular mycorrhizal (AM) fungi in shaping plant communities, but little is known about the factors determining the biomass and coexistence of several types of AM fungi in a plant community. Here, using a consumer-resource framework that treats the relationship between plants and fungi as simultaneous, reciprocal exploitation, we investigated what patterns of dynamic preferential plant carbon allocation to empirically-defined fungal types (on-going partner choice) would be optimal for plants, and how these patterns depend on successional dynamics. We found that ruderal AM fungi can dominate under low steady-state nutrient availability, and competitor AM fungi can dominate at higher steady-state nutrient availability; these are conditions characteristic of early and late succession, respectively. We also found that dynamic preferential allocation alone can maintain a diversity of mutualists, suggesting that on-going partner choice is a new coexistence mechanism for mutualists. Our model can therefore explain both mutualist coexistence and successional strategy, providing a powerful tool to derive testable predictions.

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 many other models of population growth will not lead to unbounded growth. We find that when density dependence is decelerative, the effect of mutualism is greater than when density dependence is accelerative. Although there is a greater benefit at equilibrium of a mutualist partner, decelerative density dependence tends to destabilize populations whereas accelerative density dependence is always stable. Incidentally, even when we model density dependence in birth and death rates separately, as long as one of the rates shows accelerative density dependence, populations will always be 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.

In situations where native mutualists have become extinct, non-native species may partner with remnant native species. However, non-native mutualists may differ behaviorally from extinct native mutualists. In the case of pollination, novel relationships between natives and non-natives could differ both quantitatively and qualitatively from native-native relationships. In Hawaii, the non-native Japanese White-eye (Zosterops japonicus) has largely replaced endemic birds as pollinator of the endemic Clermontia parviflora and C. mon- tis-loa. We surveyed Clermontia patches and found that they ranged from 106 to 1198 m in diameter. We performed manual pollina- tion of flowers with pollen taken from plants at five distance categories, ranging from 0 (self-fertilization) to 20 km, and examined the germination of resulting seeds. We used radiotelemetry to estimate daily Japanese White-eye movement distances. Percent germi- nation of seeds after short- to intermediate-distance pollination crosses (i.e., 20-1200 m, or intra-patch pollen transfer distances) sig- nificantly exceeded germination of seeds from selfed trials for C. parviflora. No significant differences in germination rates among treatments were detected for C. montis-loa. The maximum daily movement distances of radio-tracked birds were generally

Traditional explorations of interspecific interactions have generated extensive bodies of theory on mutualism and disease independently, but few studies have considered the interaction between them. We developed a model exploring the interactions among a fungal mutualist, a viral pathogen, and their shared plant host. Both microbes were assumed to alter the uptake and use of nutrients by the plant. We found that the productivity of the system and the strength of the plant–fungal mutualism influenced community dynamics. In particular, at low productivity, the pathogen may depend on the presence of the fungal mutualist for persistence. Furthermore, under some conditions, both the productivity of the system and the strength of the plant–fungal mutualism may simultaneously cause the mutualist to go extinct. We note the presence of cyclic plant–pathogen population dynamics only in the presence of the mutualist. As found in other models of consumer–resource interactions, cyclic dynamics were driven by high productivity, but, in contrast to simpler systems, high pathogen effectiveness did not consistently lead to cyclic dynamics. In total, association with mutualists can alter host–pathogen interactions, and the reverse is also true in that pathogens may alter host–mutualist interactions.

International audience; Biological market theory has been used successfully to explain cooperative behavior in many animal species. Microbes also engage in cooperative behaviors, both with hosts and other microbes, that can be described in economic terms. However, a market approach is not traditionally used to analyze these interactions. Here, we extend the biological market framework to ask whether this theory is of use to evolutionary biologists studying microbes. We consider six economic strategies used by microbes to optimize their success in markets. We argue that an economic market framework is a useful tool to generate specific and interesting predictions about microbial interactions, including the evolution of partner discrimination, hoarding strategies, specialized versus diversified mutualistic services, and the role of spatial structures, such as flocks and consortia. There is untapped potential for studying the evolutionary dynamics of microbial systems. Market theory can help structure this potential by characterizing strategic investment of microbes across a diversity of conditions.

Mutualistic and antagonistic interactions coexist in nature. However, little is understood about their relative roles and interactive effects on multispecies coexistence. Here, using a three-species population dynamics model of a resource species, its exploiter, and a mutualist species, we show that a mixture of different interaction types may lead to dynamics that differ completely from those of the isolated interacting pairs. More specifically, a combination of globally stable antagonistic and mutualistic subsystems can lead to unstable population oscillations, suggesting the potential difficulty in the coexistence of antagonism and mutualism. Mutualism-induced instability arises from the indirect positive effect of mutualism on the exploiter. Furthermore, for a three-species system with a stronger mutualistic interaction to persist stably, a weaker antagonistic interaction is required. Network studies of communities composed of one type of interaction may not capture the dynamics of natural communities.

An autonomous ordinary differential equations model has been developed representing a system of populations interacting in a simple food chain and a mutualist. The case of facultative mutualism between the prey at the lowest trophic level and the mutualist is considered. Criteria are developed for stability and persistence of the populations.

How ecological context shapes mutualistic relationships remains poorly understood. We combined long-term tree census data with ant censuses in a permanent 25-ha Amazonian forest dynamics plot to evaluate the effect of the mutualistic ant Myrmelachista schumanni (Formicinae) on the growth and survival of the common Amazonian tree Duroia hirsuta (Rubiaceae), considering its interactions with tree growth, population structure, and habitat. We found that the mutualist ant more than doubled tree relative growth rates and increased odds of survival. However, host tree size and density of conspecific neighbors modified the effect of the ant. Smaller trees hosting the mutualist ant consistently grew faster when surrounded by higher densities of conspecifics, suggesting that the benefit to the tree outweighs any negative effects of high conspecific densities. Moreover, our findings suggest that the benefit afforded by the ant diminishes with plant age and also depends on the density of conspecific neighbors. We provide the first long-term large-scale evidence of how mutualism affects the population biology of an Amazonian tree species. © 2016 by The University of Chicago.

Theory suggests that symbionts can readily evolve more parasitic or mutualistic strategies with respect to hosts. However, many symbionts have stable interactions with hosts that improve nutrient assimilation or confer protection from pathogens. We explored the potential for evolution of increased parasitism or decreased parasitism and mutualism in a natural gut symbiosis between larvae of Plutella xylostella and the microbe Enterobacter cloacae. We focused on interactions with the pathogen, Bacillus thuringiensis : selecting for parasitism in terms of facilitating pathogen infection, or increased mutualism in terms of host protection. Selection for parasitism led to symbionts increasing pathogen-induced mortality but reduced their competitive ability with pathogens and their in vitro growth rates. Symbionts did not evolve to confer protection from pathogens. However, several lineages evolved reduced parasitism, primarily in terms of moderating impacts on host growth, potentially because prudence pays dividends through increased host size. Overall, the evolution of increased parasitism was achievable but was opposed by trade-offs likely to reduce fitness. The evolution of protection may not have occurred because suppressing growth of B. thuringiensis in the gut might provide only weak protection or because evolution towards protective interactions was opposed by the loss of competitive fitness in symbionts.