Search

On vulnerable oceanic island ecosystems, non-native species may form novel mutualistic interactions with one another and foster establishment. On Bermuda, the omnivorous Great Kiskadee Pitangus sulphuratus was introduced to control the invasive Anolis lizard population, but feeds on many other species of plants and animals. Here we investigated whether the Kiskadee may act as an effective seed disperser of the introduced alien plant, the Orange Jessamine Murraya paniculata. In 2022 and 2023 we collected pellets regurgitated by Kiskadees, and found that 96% (N=26) contained Jessamine seeds. In 2023 we carried out an experiment to compare the germination rates of whole Jessamine fruits with manually de-fleshed seeds and those extracted from Kiskadee regurgitates. Across groups, Jessamine seeds germinated 52.6% of the time. We found only a non-significant tendency for de-fleshed seeds to germinate more often than seeds with flesh (67% vs 49%). Our study highlights that Kiskadee can act as an effective seed disperser of Jessamine in an oceanic island ecosystem. [ABSTRACT FROM AUTHOR]

The current paper presents an integrated formal model of typical and atypical development based on the mechanisms of mutualism and resource competition. The mutualistic network model is extended with the dynamics of competition for limited resources, such as time and environmental factors. The proposed model generates patterns that resemble established phenomena in cognitive development: the positive manifold, developmental phases, developmental delays and lack of early indicators in atypical development, developmental regression, and "quasi‐autism" caused by extreme environmental deprivation. The presented modeling framework fits a general movement towards formal theory construction in psychology. The model is easy to replicate and develop further, and we offer several avenues for future work. [ABSTRACT FROM AUTHOR]

Research on newborn immunity has revealed the importance of cell ontogeny, feto-maternal tolerance, and the transfer of maternal antibodies. Less is known about postnatal adaptation to environmental exposures. The microbiome and its importance for health have been extensively studied, but it remains unclear how mutually beneficial relationships between commensal microbes and human cells first arise and are maintained throughout life. Such immune-microbe mutualism, and perturbations thereof, is most likely a root cause of increasing incidences of immune-mediated disorders such as allergies and autoimmunity across many industrialized nations during the past century. In this Review, I discuss our current understanding of immune development and propose that mismatches among ancestral, early-life, and adult environments can explain perturbations to immune-microbe interactions, immune dysregulation, and increased risks of immune-mediated diseases. [ABSTRACT FROM AUTHOR]

In this paper we study the dynamics of one ammensal and two species helping mutually one another. Here the first species(x) ammensal on the other two species (y, z), which are mutually helping one another. A distributed type delay is incorporated in the interaction of second and third species with the first species. Co-existing state of the system is identified and the stability is studied at this point. And numerical simulation is carried out to study the stability of the system using exponential type of kernel. We observed that the delay parameters improved the mutualistic species' densities. [ABSTRACT FROM AUTHOR]

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 (>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. [ABSTRACT FROM AUTHOR]

Global pollinator decline is a major concern. Several factors—climate change, land-use change, the reduction of flowers, pesticide use, and invasive species—have been suggested as the reasons. Despite being a potential reason, the effect of ants on flowers received less attention. The consequences of ants being attracted to nectar sources in plants vary depending upon factors like the nectar source's position, ants' identity, and other mutualists interacting with the plants. We studied the interaction between flower-visiting ants and pollinators in Cucurbita maxima and compared the competition exerted by native and invasive ants on its pollinators to examine the hypothesis that the invasive ants exacerbate more interference competition to pollinators than the native ants. We assessed the pollinator's choice, visitation rate, and time spent/visit on the flowers. Regardless of species and nativity, ants negatively influenced all the pollinator visitation traits, such as visitation rate and duration spent on flowers. The invasive ants exerted a higher interference competition on the pollinators than the native ants did. Despite performing pollination in flowers with generalist pollination syndrome, ants can threaten plant-pollinator mutualism in specialist plants like monoecious plants. A better understanding of factors influencing pollination will help in implementing better management practices. [ABSTRACT FROM AUTHOR]

Societal Impact Statement: Coevolutionary processes, which have governed interactions between organisms throughout the history of life, also serve as an engine of ecosystem services for humans. The escalating arms races between plants and herbivores, flowers and pollinators, have generated a cornucopia of foods, raw materials, perfumes, spices, ornamentals, medicines, and drugs. Human history is replete with aesthetic as well as economic inspiration drawn from such plants. Our future may depend on similar inspiration, as we confront novel health, agricultural, and environmental challenges in the face of global change. Summary "Coevolution" was coined to conceptualize escalating arms races between plants and herbivores in evolutionary time, often mediated by natural products. Our current view embraces broader coevolutionary relationships between obligate mutualists, symbionts, parasites, and enemies, which frequently increase rates of diversification in coevolving lineages. Because humans benefit from the foods, materials, and drugs produced by plants in response to reciprocal selective pressures, coevolutionary "escape and radiate" diversification may amplify ecosystem services along with species richness, with humans as beneficiaries. For example, coevolutionary escalation of defenses between Burseraceae and their herbivores resulted in hundreds of resinous tree species, anchoring the trade of copal, frankincense, and myrrh across the ancient world. Examination of three diverse angiosperm orders (Asparagales, Malpighiales, and Gentianales), reveals ecosystem services in the form of alkaloids and hallucinogens, perfumes, spices, coffee, and rubber. Pollinator‐mediated selection by hawk moths and bats gave rise to heavily perfumed "moonflowers" (gardenias and jasmines) with aesthetic appeal to humans, and to immense blooming displays by agave plants, co‐opted by humans as a source of tequila and mezcal. Even when pollinator‐mediated diversification does not arise through coevolution, the resulting biotic richness provides evolutionary insights as well as ecosystem services. The convergent evolution of "kettle‐trap" flowers in species‐rich plant lineages (Aristolochia and Ceropegia) reveals the surprising value of small flies as pollinators and the opportunity to develop biocontrol that leverages floral features attractive to agricultural pests and disease vectors. This article highlights coevolution as a source of ecosystem services and potential solutions to the emerging challenges of global change. [ABSTRACT FROM AUTHOR]

Invasive insect pests are known to cause yield loss and economic damage to grain sorghum crops (Sorghum bicolor). This damage can be exacerbated by invasive insect mutualisms, or beneficial interactions. For example, tawny crazy ants (Nylanderia fulva) (Hymenoptera:Formicidae) (TCA) tend sugarcane aphids (Melanaphis sacchari) (Hemiptera:Aphididae) (SCA) for the honeydew or sugary excretion that they produce from feeding on the plant. This tending can reduce plant nutrients, which decreases plant health. Currently, it has not been studied whether the mutualism between TCA and SCA has any effects on grain sorghum health. To access potential plant health effects of this mutualism, potted grain sorghum plants of similar development were evaluated in a greenhouse environment. Plants were evaluated in pairs, with each individual plant having 25 sexually mature SCA and the treatment plants having an addition of 300 TCA workers. Plants were enclosed in individual fine mesh cages and placed inside a Fluon lined bin to prevent the organisms from escaping. Damage was assessed by measuring the dry root weight, change in leaf chlorosis, and change in plant stem diameter after the 14-day experiment. There were no statistically significant differences found in the treatments for dry root weight (P = 0.61), leaf chlorosis (P = 0.37) or stem growth (P = 0.25). Future studies should increase the duration of the experiment to determine potential effects of long-term interactions of TCA and SCA on grain sorghum health. Monitoring and controlling ant-aphid mutualisms may be important for the Integrated Pest Management for this agricultural crop. [ABSTRACT FROM AUTHOR]

Mutualistic interactions play a major role in shaping the Earth's biodiversity, yet the consistent drivers governing these beneficial interactions are unknown. Using a long-term (8 year, including > 256 h behavioural observations) dataset of the interaction patterns of a service-resource mutualism (the cleaner-client interaction), we identified consistent and dynamic predictors of mutualistic outcomes. We showed that cleaning was consistently more frequent when the presence of third-party species and client partner abundance locally increased (creating choice options), whilst partner identity regulated client behaviours. Eight of our 12 predictors of cleaner and client behaviour played a dynamic role in predicting both the quality (duration) and quantity (frequency) of interactions, and we suggest that the environmental context acting on these predictors at a specific time point will indirectly regulate their role in cleaner-client interaction patterns: context-dependency can hence regulate mutualisms both directly and indirectly. Together our study highlights that consistency in cleaner-client mutualisms relies strongly on the local, rather than wider community—with biodiversity loss threatening all environments this presents a worrying future for the pervasiveness of mutualisms. [ABSTRACT FROM AUTHOR]

Herbivorous insects have evolved various defensive strategies to avoid their primary enemies, parasitoids. Many species of Lycaenidae (Lepidoptera) have food-for-protection mutualism with ants in their larval stages, where larvae produce nectar for ants and in return ants exclude parasitoids as well as predators. Myrmecophilous relationships are divided into two categories, obligate and facultative, by degrees of myrmecophily. Although parasitoids attacking obligate lycaenids always encounter lycaenid-specific ant species, parasitoids that use facultative lycaenids are likely to encounter diverse ant species showing various defense systems. However, we know little about the parasitoid community of facultative lycaenid larvae. In this study, we investigated the mutualistic ant and parasitoid communities of a facultative myrmecophilous species, Arhopala japonica, in seven localities in Japan. The present field observation newly recorded four ant species attending A. japonica larvae, and combined with the previous data, the number of attending ant species reached 16, which is nearly the maximum number of reported attending ant species among myrmecophilous lycaenids. However, the present study revealed that almost all parasitized A. japonica larvae were attacked by a single braconid species, Cotesia sp. near inducta. We also assessed the efficiency of facultative ant defense against the parasitoid in the laboratory and revealed that oviposition by Cotesia sp. near inducta females was almost completely hindered when A. japonica larvae were attended by ants. This suggests that the dominant parasitoid does not have effective traits to overcome defensive behavior of ants and that the female wasps oviposit mainly in A. japonica larvae without intensive attendance. [ABSTRACT FROM AUTHOR]

Flower visitation does not necessarily mean pollination. In this sense, floral visitors can either act as mutualists (pollinators) or antagonists (floral robbers/thieves), indicating that these interactions are part of a continuum and that a visitor species can present multiple behaviours. We included both mutualistic and antagonistic interactions between plants and floral visitors in a multilayer network to explore the consequences (at the community level) of the dual roles played by flower visitors. The multilayer network of interactions was formed by herbaceous plants (12 species) and insects that visited their flowers (21 species) in an area of Atlantic Forest in Brazil from Jul 2015 to May 2016. The two layers presented similar structures, with high overlap between them. Similar to what was expected, the antagonistic layer was more modular and specialized than the mutualistic layer. Some visitor species exhibited highly central, dual roles, acting as both antagonists and mutualists. Most behaved consistently as mutualists in all their visits, especially bees, which formed a predominantly mutualistic group. Butterflies represented a mixed group in relation to their visits and flies made more antagonistic visits. This research represents an important step towards understanding the role of mutualisms and antagonisms in the structure of interaction networks between herbaceous plants and floral visitors in tropical environments. [ABSTRACT FROM AUTHOR]

Urban green areas have become an important tool for biodiversity conservation in cities. However, land use and the different management practices applied to these areas determine their effectiveness as biodiversity refuges within cities. In our study, we compare the biodiversity of three bioindicator groups of arthropods (ants, spiders and harvestmen) found in eleven urban green sites in Warsaw (Poland). The studied sites represent three categories of management: botanical gardens, public parks and urban woodlands. Our aim was to determine the effect of the type of management (as urban green categories) on arthropod communities in urban areas. [ABSTRACT FROM AUTHOR]

Obligate symbiosis evolved from free-living individuals most likely via the intermediate stage of facultative symbiosis. However, why should facultative symbionts, who can live independently but also benefit from their partners if these are available, give up this best of both worlds? Using the adaptive dynamics approach, we analyse a simple model, focusing on one partner of the symbiosis, to gain more insight into the selective forces that make individuals forgo the ability to reproduce in the free-living state. Our results suggest that, similar to the parasitism-mutualism continuum, the free-living way of life and obligate symbiosis are two extremes of a continuum of the ability to reproduce independently of a partner. More importantly, facultative symbiosis should be the rule as for many parameter combinations completely giving up independent reproduction or adopting a pure free-living strategy is not so easy. We also show that if host encounter comes at a cost, individuals that put more effort into increasing the chances to meet with their partners are more likely to give up the ability to reproduce independently. Finally, our model does not specify the ecological interactions between hosts and symbionts but we discuss briefly how the ecological nature of an interaction can influence the transition from facultative to obligate symbiosis. [ABSTRACT FROM AUTHOR]

Mutualistic symbiosis can be regarded as interspecific division of labour, which can improve the productivity of metabolites and services but deteriorate the ability to livewithout partners. Interestingly, even in environmentally acquired symbiosis, involved species often rely exclusively on the partners despite thelethal riskof missing partners. To examinethis paradoxical evolution, we explored the coevolutionary dynamics in symbiotic species for the amount of investment in producing their essential metabolites, which symbiotic species can share. Our study has shown that, even if obtaining partners is difficult, ‘perfect division of labour’ (PDL) can be maintained evolutionarily, where each species perfectlyspecializes in producing one of the essential metabolites so that every member entirely depends on the others for survival, i.e. in exchange for losing the ability of living alone. Moreover, the coevolutionary dynamics shows multistability with other states including a state without any specialization. It can cause evolutionary hysteresis: once PDL has been achieved evolutionarily when obtaining partners was relatively easy, it is not reverted even if obtaining partners becomes difficult later. Our study suggests that obligate mutualism with a high degree of mutual specialization can evolve and be maintained easier than previously thought. [ABSTRACT FROM AUTHOR]

The local, global or functional extinction of species or populations of animals, known as defaunation, can erode important ecological services in tropical forests. Many mutualistic interactions, such as seed dispersal of large seeded plants, can be lost in large continuous forests due to the rarity of large-bodied mammalian frugivores. Most of studies that try to elucidate the effects of defaunation on seed dispersal focused on primates or birds, and we lack a detailed understanding on the interactions between ground-dwelling fauna and fleshy fruits. Using camera traps in forest areas with different degrees of defaunation, we described the organization of frugivory networks involving birds, mammals and plants. We recorded 375 frugivory interactions between 21 frugivores and 150 fruiting trees of 30 species of fleshy fruit plants in six sites in continuous Atlantic forest of Brazil. We found that small frugivores—particularly small rodents and birds—were responsible for 72% of the events of frugivory. Large frugivores, such as tapirs and peccaries, were responsible for less than 21% of frugivory events. Our results indicate that the interactions between flesh fruiting plants and frugivores are dominated by small frugivores, an indication of a functional loss of large frugivores in this endangered biome. [ABSTRACT FROM AUTHOR]

Animals may host diverse bacterial communities that can markedly affect their behavioral physiology, ecology, and vulnerability to disease. Fungus-farming ants represent a classical example of mutualism that depends on symbiotic microorganisms. Unraveling the bacterial communities associated with fungus-farming ants is essential to understand the role of these microorganisms in the ant-fungus symbiosis. The bacterial community structure of five species of fungus-farmers (non-leaf-cutters; genera Mycocepurus, Mycetarotes, Mycetophylax, and Sericomyrmex) from three different environments in the Brazilian Atlantic rainforest (lowland forest, restinga forest, and sand dunes) was characterized with amplicon-based Illumina sequencing of 16 S ribosomal RNA gene. Possible differences in bacterial communities between ants internal to the nest (on the fungus garden) and external foragers were also investigated. Our results on the richness and diversity of associated bacteria provide novel evidence that these communities are host- and colony-specific in fungus-farming ants. Indeed, the bacterial communities associated with external foragers differ among the five species, and among colonies of the same species. Furthermore, bacterial communities from internal ants vs. foragers do not differ or differ only slightly within each ant species. This study highlights the importance of describing ant-associated bacterial communities to better understand this host-bacterial interaction in the social environment of insect colonies and provides the foundation for future studies on the ecological and evolutionary processes that drive the success of fungus-farming ants. [ABSTRACT FROM AUTHOR]

In several highly specialized plant-insect interactions, scent-mediated specificity of pollinator attraction is directed by the emission and detection of volatile organic compounds (VOCs). Although some plants engaged in such interactions emit singular compounds, others emit mixtures of VOCs commonly emitted by plants. We investigated the chemical ecological bases of host plant recognition in the nursery pollination mutualism between the dioecious Ficus carica and its specific pollinator Blastophaga psenes. Using Y-tube olfactometer tests, we show that B. psenes females are attracted by VOCs of receptive figs of both sexes and do not exhibit preference for VOCs of either male or female figs. Electrophysiological tests and chemical analysis revealed that of all the VOCs emitted by receptive figs, only five were found to be active on female antennae. Behavioural tests show that, in contrast to VOCs presented alone, only a blend with a particular proportion of four of these VOCs is as attractive as the odour of receptive figs, and that if there is a very small change in this blend proportion, the pollinator is no longer attracted. This study revealed that in highly specialized mutualistic interactions specificity could be mediated by a particular blend of common compounds emitted by plants. [ABSTRACT FROM AUTHOR]

Summary: Although mutualistic interactions are widespread and essential in ecosystem functioning, the emergence of uncooperative cheaters threatens their stability, unless there are some physiological or ecological mechanisms limiting interactions with cheaters.In this framework, we investigated the patterns of specialization and phylogenetic distribution of mycoheterotrophic cheaters vs noncheating autotrophic plants and their respective fungi, in a global arbuscular mycorrhizal network with> 25 000 interactions.We show that mycoheterotrophy evolved repeatedly among vascular plants, suggesting low phylogenetic constraints for plants. However, mycoheterotrophic plants are significantly more specialized than autotrophic plants, and they tend to be associated with specialized and closely related fungi. These results raise new hypotheses about the mechanisms (e.g. sanctions, or habitat filtering) that actually limit the interaction of mycoheterotrophic plants and their associated fungi with the rest of the autotrophic plants.Beyond mycorrhizal symbiosis, this unprecedented comparison of mycoheterotrophic vs autotrophic plants provides a network and phylogenetic framework to assess the presence of constraints upon cheating emergences in mutualisms. [ABSTRACT FROM AUTHOR]

This study evaluates changes in the diversity and composition of ants that inhabit contrasting environmental conditions (green and gray spaces) in two cities of different size and degree of urbanization: Xalapa and Coatepec (Veracruz, Mexico), both of which are surrounded by cloud forest remnants, croplands and pastures. In each city, a green space and a gray space of similar area were selected (~ 31 ha) and ten sampling sites were randomly placed within each environment. Tuna in oil and honey were used as baits to collect soil ants, entomological nets to capture vegetation ants and Winkler sacks for leaf-litter ants. Ant species richness (0D) and diversity (1D) was greater in Coatepec (the smaller and less urbanized city) than in Xalapa. However, the pattern observed when comparing green and gray spaces differed between the cities: the greatest diversity (0D and 1D) was observed in the gray space of Coatepec and the lowest diversity in the green space of Xalapa. In both cities, the similarity of species composition between habitat conditions was close to 50% and the comparison of green spaces between the cities showed that these are more different to each other than is the case with the gray spaces. These results suggest that the characteristics of each city influence the ant diversity contained in green and gray spaces differently and can promote differentiation in species composition within the same city. [ABSTRACT FROM AUTHOR]

1. Bipartite network analyses are increasingly being used to better understand mutualistic and antagonistic plant–insect interactions at the community level. As a result of taxonomic limitations, it is usually very difficult to identify all nodes of a network down to the species level and many studies leave some specimens identified as lower resolution taxa. Accordingly, we do not know how much a lower resolution taxonomic representation changes the network structure compared with a representation with all nodes at species level. 2. The present study aimed to test whether insect–plant networks built using different combinations of taxonomic levels can still preserve the same basic structure of networks built only with species. 3. In total, 73 bipartite published interaction networks (mutualistic and antagonistic) were selected, which were turned into binary networks and reconstructed using the nodes classified as species, genus, family or order (representing different levels of classification difficulty). The network structures were compared using their binary representations mainly using connectance, NODF (Nestedness metric based on Overlap and Decreasing Fill) and modularity. 4. The mutualistic network structure was strongly linearly related to the original network structures if all nodes were grouped up to genus level. In antagonistic networks, the structure was related to the original network only if nodes were only grouped at the species level. 5. The findings of the present study are especially helpful for comparative network studies, such as those assessing the effects of environmental gradients. For mutualistic networks, Citizen Science programmes can provide useful ecological indicators, even with its taxonomic limitations. [ABSTRACT FROM AUTHOR]

1. Predator–prey interactions, especially those involving herbivorous insects, are of great importance in maintaining biodiversity. Predation pressure varies temporally in response to prey availability and activity. However, little is known about the patterns and drivers of fluctuations in predation pressure at fine temporal scales. 2. Artificial caterpillars (placed on plant leaves at breast height) were used to assess changes in predation pressure across four time intervals of the day in a monsoonal tropical rainforest in south‐west China. The study examined how assemblage composition of arboreal ants, the dominant predators, changed across the same time intervals. The potential linkages between biotic (arboreal ants) and abiotic (temperature and light intensity) factors with predation rate were evaluated. 3. Predation rate on caterpillars during the early part of the night (19.00–01.00 hours) was significantly higher than in the morning, afternoon, or late night. Ant assemblage composition, rather than species richness or total abundance, best explained the variations in predation rate on artificial caterpillars. 4. The results help to strengthen understanding of trophic interactions by demonstrating that predation pressure fluctuates at finer timescales than previously tested, and that a particular set of ant species may play major roles in predation on caterpillars and possibly other organisms. [ABSTRACT FROM AUTHOR]

Animal interactions play an important role in understanding ecological processes. The nature and intensity of these interactions can shape the impacts of organisms on their environment. Because ants and termites, with their high biomass and range of ecological functions, have considerable effects on their environment, the interaction between them is important for ecosystem processes. Although the manner in which ants and termites interact is becoming increasingly well studied, there has been no synthesis to date of the available literature. Here we review and synthesise all existing literature on ant–termite interactions. We infer that ant predation on termites is the most important, most widespread, and most studied type of interaction. Predatory ant species can regulate termite populations and subsequently slow down the decomposition of wood, litter and soil organic matter. As a consequence they also affect plant growth and distribution, nutrient cycling and nutrient availability. Although some ant species are specialised termite predators, there is probably a high level of opportunistic predation by generalist ant species, and hence their impact on ecosystem processes that termites are known to provide varies at the species level. The most fruitful future research direction will be to evaluate the impact of ant–termite predation on broader ecosystem processes. To do this it will be necessary to quantify the efficacy both of particular ant species and of ant communities as a whole in regulating termite populations in different biomes. We envisage that this work will require a combination of methods, including DNA barcoding of ant gut contents along with field observations and exclusion experiments. Such a combined approach is necessary for assessing how this interaction influences entire ecosystems. [ABSTRACT FROM AUTHOR]

The establishment and spread of non-native species often results in negative impacts on biodiversity and ecosystem function. Several species of saltcedar, Tamarix spp. L., have been recently naturalized in large portions of the United States where they have altered plant and animal communities. To test the prediction that saltcedar negatively affects invertebrates, we measured ant genera diversity and the activity density of the exotic isopod Armadillidium vulgare Latrielle (Isopoda: Oniscoidea) for 2 yr using pitfall traps located within 30 5-m2 plots with or without saltcedar at a south-central Nebraska reservoir. From 2005 to 2006, we collected 10,837 ants representing 17 genera and 4,953 A. vulgare. Per plot, the average number of ant genera was not different between saltcedar (x̅ = 3.9) and non-saltcedar areas (x̅ = 3.9); however, saltcedar plots were compositionally different and more similar from plot to plot (i.e., they had lower beta diversity than control plots) in 2005, but not in 2006. Isopods were likewise temporally affected with higher activity density (+89%) in control plots in 2005, but higher activity density (+27%) in saltcedar plots in 2006. The observed temporal differences occurred as the drought that initially enabled the saltcedar invasion became less severe in 2006. Combined, our results suggest that invertebrate groups like ants, which are generally omnivorous, may be better equipped than more specialized taxa like detritivores to withstand habitat changes due to invasions by non-native species, especially during extreme weather events such as prolonged droughts. [ABSTRACT FROM AUTHOR]

Positive interactions are observed at high frequencies in nearly all living systems, ranging from human and animal societies down to the scale of microbial organisms. However, historically, detailed ecological studies of mutualism have been relatively unrepresented. Moreover, while ecologists have long portrayed competition as a stabilizing process, mutualism is often deemed destabilizing. Recently, several key modelling studies have applied random matrix methods, and have further corroborated the instability of mutualism. Here, I reassess these findings by factoring in species densities into the "community matrix," a practice which has almost always been ignored in random matrix analyses. With this modification, mutualistic interactions are found to boost equilibrium population densities and stabilize communities by increasing their resilience. By taking into account transient dynamics after a strong population perturbation, it is found that mutualists have the ability to pull up communities by their bootstraps when species are dangerously depressed in numbers. Mutualism is typically portrayed as a destabilizing process in community ecology. Here, via a random matrix model that considers species density, the author shows that mutualistic interactions can, in fact, enhance population density at equilibrium and increase community resilience to perturbation. [ABSTRACT FROM AUTHOR]

Observational and experimental studies have shown that an interaction class between two species (be it mutualistic, competitive, antagonistic, or neutral) may switch to a different class, depending on the biotic and abiotic factors within which species are observed. This complexity arising from the evidence of context-dependencies has underscored a difficulty in establishing a systematic analysis about the extent to which species interactions are expected to switch in nature and experiments. Here, we propose an overarching theoretical framework, by integrating probabilistic and structural approaches, to establish null expectations about switches of interaction classes across environmental contexts. This integration provides a systematic platform upon which it is possible to establish new hypotheses, clear predictions, and quantifiable expectations about the context-dependency of species interactions. Species interactions are not fixed and determine the dynamics and persistence of ecological communities. Empirical work has shown that the switching frequency of species interactions is context-dependent. The context-dependency of multispecies communities has underscored a difficulty in establishing a quantifiable and systematic framework about the expected frequency of interaction switches. We propose a structural probabilistic framework to systematically address the uncertainty associated with context-dependency and derive null expectations about the switching frequency of interaction classes in multispecies communities. [ABSTRACT FROM AUTHOR]

Theologians are familiar with competitive relationships between organisms. Biology, however, also presents us with organisms engaged in mutually supportive relationships, in a pattern both widespread and often crucial for survival. This paper considers some of the challenges to traditional accounts of Christian doctrine—principally to creation, Christology and eschatology—posed by biological mutualism, especially in the phenomenon of compound organisms, composed of cells from more than one species. It also suggests ways in which theological traditions preserve philosophical resources that can be of use in thinking theologically about inter-organism relationships, and to philosophical discussions of biological mutualism more generally. [ABSTRACT FROM AUTHOR]

The concepts of symbiosis and mutualism advance our understanding of biology and have important implications for metaphysics and religious philosophy. However, symbiosis and mutualism presume that organisms are still individuals that relate to one another as distinct independent entities. While we agree that symbiosis and mutualism are important to understand, we suggest that a growing body of life science research supports a more accurate and an even more profoundly interconnected view of life as contingently existent and mutually constituting. While potentially disturbing to human self-understanding, this view could have a beneficial impact on theological reasoning and practical pastoral thinking. [ABSTRACT FROM AUTHOR]

The role of close inter-species relationships has become clearer in contemporary biology than ever before, not least the importance of mutually beneficial interactions (mutualism). This paper surveys this area of science, presenting it for a non-specialist readership, as part of a journal edition assembling theological engagements with biological mutualism, as a provocation to interdisciplinary research between the natural sciences and the arts and humanities, is a description of the extent and significance of mutualism in relation to ecology, evolution, and human health, along with a discussion of the history of writing on the theme, and a glossary. [ABSTRACT FROM AUTHOR]

• The distribution of pavement ants depends on the climate–urbanization interaction. • Tetramorium immigrans subsists under harsher climate by colonizing urbanized areas. • Combining climate and urbanization is a crucial challenge for distribution studies. • Tetramorium immigrans is likely an invasive species in urban areas. Global changes, such as climate and urbanization, are strongly entwined and aggravated by the development of human activities, which also intensifies the human-mediated dispersal of species. However, few studies have explicitly considered the combined influence of urbanization and climate on species expansion. We investigated the combined roles of climate, urbanization and human-mediated dispersal in the expansion of Tetramorium immigrans (an invasive pavement ant in North America) in urban areas of South-eastern France. A total of 544 T. immigrans individuals were sampled from 16 urban gradients and genotyped at 14 microsatellite markers. Based on molecular ecology methods and statistical modelling, we evaluated the impact of climate and urbanization on its distribution patterns. Through the combined study of the occurrence probabilities of T. immigrans , its genetic structure and the founder effects within its populations, the effect of climate–urbanization interaction on species distribution was clearly evidenced, suggesting that in the north of its range, T. immigrans subsists under harsher climate by colonizing the most urbanized areas. Many taxa may conform to such pattern, making the combined study of climate and urbanization a necessary challenge for future studies. Distribution patterns concurred with similar observations in the American invasive range of T. immigrans , making it likely that it may not be native to the northernmost part of its European range. Cryptic invasions or discreet range shifts in response to increasing urbanization are likely to occur in many taxa, especially in ants, and deserve increased attention from researchers and managers alike. [ABSTRACT FROM AUTHOR]

Ecosystems are composed of complex networks of many species interacting in different ways. While ecologists have long studied food webs of feeding interactions, recent studies increasingly focus on mutualistic networks including plants that exchange food for reproductive services provided by animals such as pollinators. Here, we synthesize both types of consumer-resource interactions to better understand the controversial effects of mutualism on ecosystems at the species, guild, and whole-community levels. We find that consumer-resource mechanisms underlying plant-pollinator mutualisms can increase persistence, productivity, abundance, and temporal stability of both mutualists and non-mutualists in food webs. These effects strongly increase with floral reward productivity and are qualitatively robust to variation in the prevalence of mutualism and pollinators feeding upon resources in addition to rewards. This work advances the ability of mechanistic network theory to synthesize different types of interactions and illustrates how mutualism can enhance the diversity, stability, and function of complex ecosystems. Aside from their pollination function, pollinators consume and are consumed by other members of ecological communities; these relationships could explain the controversial effects of pollinators on ecological networks. Here the authors show that when mutualists such as pollinators are introduced into food webs, they increase ecosystem biodiversity, stability, and function. [ABSTRACT FROM AUTHOR]

Greenhouse crops are thought to be simplified ecosystems because they often consist of monocultures that are relatively isolated from their environment. However, insect pests are still able to colonize these protected crops, which threaten their yields. Similarly, natural enemies of pests may be able to colonize greenhouses, providing a form of natural biological pest control. Protected strawberry crops are grown in several types of greenhouses that vary in their degree of openness. Crops often suffer from aphid outbreaks, which can be partly controlled by insect parasitoids immigrating from the surrounding environment. We investigated variations over space and time in both the aphid and parasitoid community diversity and species assemblages associated with protected strawberry crops. We sampled aphids and parasitoids in five regions of France in the spring and summer of two successive years. Despite the relative isolation of these protected crops, we identified a high aphid species richness in them, even at the greenhouse scale. Aphid community composition varied with spatial and temporal factors, but the species assemblages present were mostly determined by local factors. Parasitoid communities were mostly similar among the studied regions, but varied between seasons, with this temporal variation being related to changes in aphid species composition. The study of trophic interactions occurring between aphids and parasitoids allowed the most prevalent and efficient parasitoid species to be identified. The structures of food webs strongly varied in time and space, compromising any prediction of "natural" biological control. We also highlighted ecological factors that can disrupt aphid biological control, such as the occurrence of hyperparasitism or the possibility of apparent mutualism between aphid species. Finally, we showed that the degree of openness of greenhouses influenced both the aphid communities and the hyperparasitism rates in them. These results provide valuable information to improve aphid biological control in protected crops. [ABSTRACT FROM AUTHOR]

The network architecture of an ecological community describes the structure of species interactions established in a given place and time. It has been suggested that this architecture presents unique features for each type of ecological interaction: e.g., nested and modular architectures would correspond to mutualistic and antagonistic interactions, respectively. Recently, Michalska-Smith and Allesina (2019) proposed a computational challenge to test whether it is indeed possible to differentiate ecological interactions based on network architecture. Contrary to the expectation, they found that this differentiation is practically impossible, moving the question to why it is not possible to differentiate ecological interactions based on their network architecture alone. Here, we show that this differentiation becomes possible by adding the local environmental information where the networks were sampled. We show that this can be explained by the fact that environmental conditions are a confounder of ecological interactions and network architecture. That is, the lack of association between network architecture and type of ecological interactions changes by conditioning on the local environmental conditions. Additionally, we find that environmental conditions are linked to the stability of ecological networks, but the direction of this effect depends on the type of interaction network. This suggests that the association between ecological interactions and network architectures exists, but cannot be fully understood without attention to the environmental conditions acting upon them. Author summary: It has been suggested that different types of species interactions lead to ecological networks with different architectures. For example, mutualistic and antagonistic interaction networks have been shown to have nested and modular architectures, respectively. Importantly, this differentiation can provide clues about the link between the dynamics and structures shaping ecological communities. Recently, Michalska-Smith and Allesina (2019) turned this assumption into a serious computational challenge for the scientific community. Here, we embrace this challenge. We confirm that network architecture alone is not enough to differentiate interaction networks. However, we show that network architectures can differentiate between mutualistic and antagonistic interaction networks by using information about their local environmental conditions. In other words, ignoring environmental information throws out the predictable patterns of network architectures along environmental gradients. Thus, this response is also a reminder that ecological networks may only make sense in the light of environmental information. [ABSTRACT FROM AUTHOR]

The modification of habitats in urban areas is thought to alter patterns of species interactions, by filtering specialist species and those at higher trophic levels. However, empirical studies addressing these hypotheses remain limited in scope and number. This work investigates (1) how main urban land uses affect predator-prey and mutualistic interactions, and (2) how specialist and generalist predators respond to size and availability of urban green spaces. In a large town in the UK, experimental colonies of ant-attended Black bean aphid Aphis fabae and non-ant-attended Pea aphid Acyrthosiphon pisum were monitored over two years. Ants were more frequently found in highly urbanised sites; however mutualistic ants were also more often encountered when the habitat was more plant diverse. Aphids were not affected by urban land uses, but A. fabae numbers were positively related to the presence of mutualists, and so indirectly affected by urbanisation. Predators were the only group negatively affected by increased urbanisation, and specialist species were positively related to increased proportion of urban green areas within the habitats. While this work supports the hypothesis that specialist predators are negatively affected by urbanisation, we also show that a fundamental ecological interaction, mutualism, is affected by urbanisation. [ABSTRACT FROM AUTHOR]

Keystone mutualisms, such as corals, lichens or mycorrhizae, sustain fundamental ecosystem functions. Range dynamics of these symbioses are, however, inherently difficult to predict because host species may switch between different symbiont partners in different environments, thereby altering the range of the mutualism as a functional unit. Biogeographic models of mutualisms thus have to consider both the ecological amplitudes of various symbiont partners and the abiotic conditions that trigger symbiont replacement. To address this challenge, we here investigate 'symbiont turnover zones'––defined as demarcated regions where symbiont replacement is most likely to occur, as indicated by overlapping abundances of symbiont ecotypes. Mapping the distribution of algal symbionts from two species of lichen-forming fungi along four independent altitudinal gradients, we detected an abrupt and consistent β-diversity turnover suggesting parallel niche partitioning. Modelling contrasting environmental response functions obtained from latitudinal distributions of algal ecotypes consistently predicted a confined altitudinal turnover zone. In all gradients this symbiont turnover zone is characterized by approximately 12°C average annual temperature and approximately 5°C mean temperature of the coldest quarter, marking the transition from Mediterranean to cool temperate bioregions. Integrating the conditions of symbiont turnover into biogeographic models of mutualisms is an important step towards a comprehensive understanding of biodiversity dynamics under ongoing environmental change. [ABSTRACT FROM AUTHOR]

Positive interspecific interactions such as mutualism, commensalism, and facilitation are globally ubiquitous. Although research on positive interactions in terrestrial and marine systems has progressed over the past few decades, comparatively little is known about them in freshwater ecosystems. However, recent advances have brought the study of positive interactions in freshwater systems to a point where synthesis is warranted.In this review, we catalogue the variety of direct positive interactions described to date in freshwater ecosystems, discuss factors that could influence prevalence and impact of these interactions, and provide a framework for future research.In positive interactions, organisms exchange key resources such as nutrients, protection, transportation, or habitat to a net benefit for at least one participant. A few mutualistic relationships have received research attention to date, namely seed‐dispersing fishes, crayfishes and their ectosymbiotic cleaners, and communal‐spawning stream fishes. Similarly, only a handful of commensalisms have been studied, primarily phoretic relationships. Facilitation via ecosystem engineering has received more attention, for example habitat modification by beavers and bioturbation by salmon.It is well known that interaction outcomes vary with abiotic and biotic context. However, only a few of studies have examined context dependency in positive interactions in freshwater systems. Likewise, positive interactions incur costs as well as benefits; conceptualising interactions in terms of net cost/benefit to participants will help to clarify complex interactions.It is likely that there are many positive interactions that have yet to be discovered in freshwater systems. To identify these interactions, we encourage inductive natural history studies combined with hypotheses deduced from general ecological models. Research on positive interactions must move beyond small‐scale experiments and observational studies and adopt a cross‐scale approach. Likewise, we must progress from reducing systems to oversimplified pairwise interactions, toward studying positive interactions in broader community contexts. Positive interactions have been greatly overlooked in applied freshwater ecology, but have great potential for conservation, restoration, and aquaculture. [ABSTRACT FROM AUTHOR]

Different modelling approaches have been used to relate the structure of mutualistic interactions with the stability of communities. However, inconsistencies arise when we compare modelling outcomes with the patterns of interactions observed in empirical studies. To shed light on these inconsistencies, we explored the network structure–stability relationship by incorporating the cost of mutualistic interactions, a long ignored feature of mutualisms, into population dynamics models. We assessed the changes in the relationship between network structure (species richness, connectance, modularity) and community stability (species persistence, resilience), and between network structure and community structural attributes (average abundance), using models with increasing levels of cost for mutualistic communities. We found that adding the potential cost of mutualistic interactions affected the strength of the network structure–stability relationship. Our results revive the question of whether the structure of mutualistic networks determines community stability. [ABSTRACT FROM AUTHOR]

Much of our understanding of mutualism is derived from pairwise obligate interactions between specialized participants. These observations may not adequately inform conservation efforts for facultative mutualist species, especially for areas in which invasive species are present and affect the mutualism. We evaluate the effects of ant attendance on larval survival for the endangered Fender's blue butterfly (Icaricia icarioides fenderi Macy) in situ and examine the effects of biotic and abiotic factors—specifically ant community composition and microhabitat structure—on this mutualistic interaction in Oregon, USA. Fender's blue larval survival was as much as three times higher in plots with a high proportion of ant attendance compared to plots in which larvae were rarely tended, and ant recruitment was reduced by dense, invasive European grasses. Thatch from these dense invasives, specifically tall oatgrass (Arrhenatherum elatius Beauv.) and tall fescue (Schedonorus arundinaceus Schreb.), are a threat to larval survival. In addition, variation in microhabitat structure determined which ant species occurred in our plots. Larvae were associated with ten ant species but primarily tended by only two: Prenolepis imparis Say and Aphaenogaster occidentalis Emery, and we observed no difference in butterfly larval survival between the two predominant ant species. Conservation efforts for this species would benefit from actions that reduce invasive grasses and facilitate ant tending interactions. Our study demonstrates how invasive grasses and forbs in degraded prairie systems can negatively impact the conservation of an at-risk species by disrupting an important mutualistic interaction. [ABSTRACT FROM AUTHOR]

BACKGROUND: Ants are known to establish antagonistic and mutualistic interactions with honeydew‐producing hemipterans, depending on the species involved and the ecological context. The aim of this work was to infer the role that such interactions play in the population dynamics of psyllids and aphids in pear orchards. Interactions were inferred from field data and periodical sampling along a 4‐year study, and from interaction assays performed under controlled conditions. RESULTS: A decline in the abundance of the pear psyllid (Cacopsylla pyri L.), parallel to an increase in the abundance of aphids, was registered over 4 years. Ants were the dominant species, representing about 90% of the predators, followed by spiders and predatory hemipterans (namely Pilophorus gallicus Remane). Ant abundance increased over the 4 years, matching the population dynamics of aphids. Evidence of mutualistic and antagonistic interactions were found for ant–aphid and ant–psyllid, respectively: (i) ant–aphid abundances on pear trees were positively correlated, and ants reduced predation on aphids by generalist predators, and (ii) ant–psyllid abundances were negatively correlated, ants have a negative effect on the psyllid population growth rates, and ants were found to prey on the psyllid. CONCLUSIONS: Because of their high abundance in comparison with other predators and the mutualistic–antagonistic relationships with aphids–psyllids, ants are considered to be the principal force behind the decline of pear psyllid populations and the increase in aphid numbers. In summary, ants contribute positively to biological control by the suppresion of pests (i.e. the psyllid) which are more damaging than those they protect (i.e. aphids). © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The dynamics and prevalence of mutualistic interactions, which are responsible for the maintenance and structuring of all ecological communities, are vulnerable to changes in abiotic and biotic environmental conditions. Mutualistic outcomes can quickly shift from cooperation to conflict, but it unclear how resilient and stable mutualistic outcomes are to more variable conditions. Tidally controlled coral atoll lagoons that experience extreme diurnal environmental shifts thus provide a model from which to test plasticity in mutualistic behavior of dedicated (formerly obligate) cleaner fish, which acquire all their food resources through client interactions. Here, we investigated cleaning patterns of a model cleaner fish species, the bluestreak wrasse (Labroides dimidiatus), in an isolated tidal lagoon on the Great Barrier Reef. Under tidally restricted conditions, uniquely both adults and juveniles were part‐time facultative cleaners, pecking on Isopora palifera coral. The mutualism was not completely abandoned, with adults also wandering across the reef in search of clients, rather than waiting at fixed site cleaning stations, a behavior not yet observed at any other reef. Contrary to well‐established patterns for this cleaner, juveniles appeared to exploit the system, by biting ("cheating") their clients more frequently than adults. We show for the first time, that within this variable tidal environment, where mutualistic cleaning might not represent a stable food source, the prevalence and dynamics of this mutualism may be breaking down (through increased cheating and partial abandonment). Environmental variability could thus reduce the pervasiveness of mutualisms within our ecosystems, ultimately reducing the stability of the system. [ABSTRACT FROM AUTHOR]