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In addition to pollution, organisms are exposed to natural variations of the biotic and abiotic factors of their environment. A battery of sub-cellular biomarkers has been measured seasonally in several populations of both Dreissena polymorpha and Dreissena rostriformis bugensis. To observe and understand the variability associated with biomarker responses, water physicochemistry, sediment contamination, and internal concentrations of contaminants in soft tissues were also considered. Results evidenced seasonal, inter-specific, and inter-populational variability of the measured responses, highlighting the needs (1) to acquire long-term data on the studied populations and (2) to incorporate environmental parameters and contamination in the interpretation of biological responses. From a biomonitoring perspective, significant relationships were identified between biomarkers, internal concentrations of contaminants in soft tissues, and sediment contamination in D. r. bugensis and, to a lesser extent, in D. polymorpha. The detailed interpretation of each biomarker of the battery measured is complex, but a global analysis of all biomarkers at once allows to obtain this signature of the contamination of the studied sites. [ABSTRACT FROM AUTHOR]

Functional traits of individuals and not just species can regulate ecological interactions with biotic and abiotic environments, yet how individual-level functional diversity (FDind) mediates the environmental effects on community properties (e.g., interaction patterns, connectivity and productivity) remains largely unexplored. Here, we assembled 4432 individuals from 30 macrophyte species across 26 lakes in south China and measured six functional traits -shoot height, specific leaf area, lamina thickness, leaf dry mass content, stem diameter and stem dry mass content—for each individual. We estimated FDind for macrophyte community in each plot using trait probability density framework. Path analysis revealed that functional richness promoted negative interactions (the absolute value of negative: positive cohesion as proxy of community interaction patterns) and thus community productivity at lower total phosphorus (TP) and shallower water, while functional divergence/redundancy reduced negative interaction and thus community productivity at shallower water, lower TP and higher altitude. Functional evenness decreased community productivity at higher TP and deeper water. Functional dissimilarity reduced community connectivity (total cohesion) and thus community productivity at deeper water and higher altitude. Our results highlight that FDind could modify the environmental effects (from local to regional) on the interaction patterns, network connectivity and productivity of macrophyte community. [ABSTRACT FROM AUTHOR]

Sympatric primate species coexist in tropical communities through interactions with the abiotic environment and other species. Determining the factors that influence primate species co-occurrence can help to inform conservation practices. Our study focused on the ecological interactions of central chimpanzees (Pan troglodytes troglodytes) and western lowland gorillas (Gorilla gorilla gorilla) with each other and their environment in a multiuse landscape. We assessed species-specific occupancy at 17 camera trap sites across different land-use types (National Park, Forest Management Units, or Community Lands) between June 2019 and May 2020 and examined the impact of fruit availability and human presence on ape presence. Across the study area, chimpanzees occupied a greater total number of sites than did gorillas, with a significantly higher proportion of occupied sites within the National Park than in other land-use types. The density of fruiting trees positively influenced the presence of gorillas but had no effect on chimpanzee presence. We found no effect of human presence on the presence of either chimpanzees or gorillas, although this analysis was limited to sites where apes were present. The probability of either species being present at a site during a given month remained stable under the conditional presence or absence of the other species, suggesting the absence of interactions between the two species at our study sites. These results support previous findings that the heterogeneous distribution of fruits and preferred resources allows chimpanzees and gorillas to limit direct competition by exploiting different feeding resources. Our findings provide insights on the factors influencing the occupancy of each species, including environmental variables and land-use type, information relevant when monitoring their coexistence within tropical communities. [ABSTRACT FROM AUTHOR]

Woody plant encroachment is influenced by interactions between the physical environment and vegetation, which create heterogenous microenvironments some of which favor shrub recruitment through mitigation of the abiotic environment. Encroachment of native shrub, Morella cerifera into grasslands on Hog Island, Virginia has been attributed to warmer winter temperature; however, recruitment of seedlings in grasslands may be impacted by multiple factors at the level of the microhabitat. Our study focuses on a critical gap in understanding factors specifically influencing M. cerifera seedling recruitment and survival. By experimentally planting M. cerifera seedlings at varying dune elevations and grass densities, we tested hypotheses that dune elevation influences the microclimate, soil characteristics and vegetation cover and that grass cover/density is related to shrub establishment. We tested these hypotheses through gathering data from temperature data loggers, conducting soil water content and chloride analyses, and determining percent cover of grasses relative to dune elevation. Results indicate that dune elevation was positively related to moderated temperatures with reduced temperature extremes and vegetation cover/composition that led to favorable locations for M. cerifera establishment and growth. Where dune elevation is > 2 m, we document an upper limit of grass cover on natural seedling establishment, suggesting a switch from facilitative to competitive effects with grass density. Overall, our work demonstrates interactions between dune elevation and medium grass density has a facilitative influence on M. cerifera establishment and can be used for future predictions of shrub growth with rising sea-levels. [ABSTRACT FROM AUTHOR]

This work summarizes the results of long-term field studies of 22 species of halophytic plants in the Elton region belonging to 4 families and 14 genera. Plants are classified according to the ecological (salt-accumulating euhalophytes, salt-secreting crinohalophytes, and salt-excluding glycohalophytes) and genetic (C3 and C4 photosynthesis) system. The conditions of the abiotic environment (level of salinity and soil moisture) under which various groups of halophytic plants grew are shown. The composition of fatty acids (FAs) of lipids in halophyte leaves is analyzed. It is concluded that the modulation of halophyte lipids, associated with changes in FAs composition depending on soil salinity and moisture, is one mechanism of plant salt tolerance at the cellular level of organization. [ABSTRACT FROM AUTHOR]

Visual systems have evolved to discriminate between different wavelengths of light. The ability to perceive color, or specific light wavelengths, is important as color conveys crucial information about both biotic and abiotic features in the environment. Indeed, different wavelengths of light can drive distinct patterns of activity in the vertebrate brain, yet what remains incompletely understood is whether distinct wavelengths can invoke etiologically relevant behavioral changes. To address how specific wavelengths in the visible spectrum modulate behavioral performance, we use larval zebrafish and a stereotypic light-search behavior. Prior work has shown that the cessation of light triggers a transitional light-search behavior, which we use to interrogate wavelength-dependent behavioral modulation. Using 8 narrow spectrum light sources in the visible range, we demonstrate that all wavelengths induce motor parameters consistent with search behavior, yet the magnitude of search behavior is spectrum sensitive and the underlying motor parameters are modulated in distinct patterns across short, medium, and long wavelengths. However, our data also establishes that not all motor features of search are impacted by wavelength. To define how wavelength modulates search performance, we performed additional assays with alternative wavelengths, dual wavelengths, and variable intensity. Last, we also tested blind larvae to resolve which components of wavelength dependent behavioral changes potentially include signaling from non-retinal photoreception. These findings have important implications as organisms can be exposed to varying wavelengths in laboratory and natural settings and therefore impose unique behavioral outputs. [ABSTRACT FROM AUTHOR]

The nurse effect is a positive interaction in which a nurse plant improves the abiotic environment for another species (beneficiary plant) and facilitates its establishment. The evergreen shrub Vaccinium vitis-idaea (a beneficiary plant) grows mainly under the dwarf shrub Pinus pumila (a nurse plant) in the alpine regions of central Japan. However, whether V. vitis-idaea shrubs under various P. pumila shrubs spread through clonal growth and/or seeds remains unclear. We investigated the clonal structure of V. vitis-idaea under the nurse plant P. pumila in Japanese alpine regions. MIG-seq analysis was conducted to clarify the clonal diversity of V. vitis-idaea in isolated and patchy P. pumila plots on a ridge (PATs), and in a plot covered by dense P. pumila on a slope adjacent to the ridge (MAT) on Mt. Norikura, Japan. We detected 28 multilocus genotypes in 319 ramets of V. vitis-idaea across 11 PATs and MAT. Three genets expanded to more than 10 m in the MAT. Some genets were shared among neighboring PATs or among PATs and MAT. These findings suggest that the clonal growth of V. vitis-idaea plays an important role in the sustainability of populations. The clonal diversity of V. vitis-idaea was positively related with the spatial size of PATs and was higher in MAT than in PATs at a small scale. Therefore, the spatial spread of the nurse plant P. pumila might facilitate the nurse effect on the genetic diversity of beneficiary plants, leading to the sustainability of beneficiary populations. [ABSTRACT FROM AUTHOR]

Anthropogenic stressors can have an impact in a broad range of physiological processes and can be a major selective force leading to rapid evolution and local population adaptation. In this study, three populations of the invasive crayfish Procambarus clarkii were investigated. They are geographically separated for at least 20 years, and live in different abiotic environments: a freshwater inland lake (Salagou lake) with no major anthropogenic influence and two other coastal wetlands regularly polluted by pesticides along the Mediterranean coast (Camargue region and Bages-Sigean lagoon). Collected adults were genetically characterized using the mitochondrial COI gene and haplotype frequencies were analyzed for genetic variability within and between populations. Results revealed a higher genetic diversity for these invasive populations than any previous report in France, with more than seven different haplotypes in a single population. The contrasting genetic diversity between the Camargue and the other two populations suggest different times and sources of introduction. To identify differences in key physiological responses between these populations, individuals from each population were maintained in controlled conditions. Data on oxygen consumption rates indicate that the Salagou and Bages-Sigean populations possess a high inter-individual variability compared to the Camargue population. The low individual variability of oxygen consumption and low genetic diversity suggest a specific local adaptation for the Camargue population. Population-specific responses were identified when individuals were exposed to a pesticide cocktail containing azoxystrobin and oxadiazon at sublethal concentrations. The Salagou population was the only one with altered hydro-osmotic balance due to pollutant exposure and a change in protease activity in the hepatopancreas. These results revealed different phenotypic responses suggesting local adaptations at the population level. [ABSTRACT FROM AUTHOR]

Across animal systems, abiotic environmental features, including timing of seasonal events and weather patterns, affect fitness. An individual's degree of social integration also has fitness consequences, but we lack an understanding of how abiotic features relate to patterns of individual sociality. A deeper understanding of this relationship could be developed from studying systems where these two links with fitness have already been identified. We explored the relationship between individual social behavior and seasonal timing, seasonal length, and weather patterns. We used social network analysis on a sixteen-year dataset of a wild population of hibernating yellow-bellied marmots (Marmota flaviventer). We fit a series of generalized linear mixed models and found that longer growing seasons before winter hibernation and longer winters were associated with increased individual sociality in the following spring. However, later snowmelt was associated with decreased sociality that spring. We found no relationship between individual sociality and various measures of precipitation and temperature. This suggests that seasonal timing and length may be a more important driver of sociality than weather patterns in this system, both as a lag and contemporary effect. Seasonal timing and length may mediate the opportunity or intensity of social interactions. The entwined relationships between the seasonal schedule and weather, and the seemingly contradictory role of winter length and snowmelt, suggests the timing of seasons and its relationship with sociality is complex and further exploration of environment-sociality relationships is required across taxa. Significance statement: While the adaptive benefits of social behavior are well studied, less is known about how features of the abiotic environment drive variation in individual social behavior. Given increasing stochasticity in the timing of seasonal events and weather patterns, mapping the environment-sociality relationship will provide important insights to the drivers of sociality in the wild. This is particularly salient for species most vulnerable to climate and environmental change, such as seasonal hibernators, like yellow-bellied marmots (Marmota flaviventer). We found that features of seasonal duration were positively associated with increased sociality, whereas the timing of seasonal onset was negatively associated. This work provides empirical evidence towards an important gap in the behavioral ecology literature. [ABSTRACT FROM AUTHOR]

Petroleum hydrocarbon (PH) pollution has mostly been caused by oil exploration, extraction, and transportation activities in colder regions, particularly in the Arctic and Antarctic regions, where it serves as a primary source of energy. Due to the resilience feature of nature, such polluted environments become the realized ecological niches for a wide community of psychrophilic hydrocarbonoclastic bacteria (PHcB). In contrast, to other psychrophilic species, PHcB is extremely cold-adapted and has unique characteristics that allow them to thrive in greater parts of the cold environment burdened with PHs. The stated group of bacteria in its ecological niche aids in the breakdown of litter, turnover of nutrients, cycling of carbon and nutrients, and bioremediation. Although such bacteria are the pioneers of harsh colder environments, their growth and distribution remain under the influence of various biotic and abiotic factors of the environment. The review discusses the prevalence of PHcB community in colder habitats, the metabolic processes involved in the biodegradation of PH, and the influence of biotic and abiotic stress factors. The existing understanding of the PH metabolism by PHcB offers confirmation of excellent enzymatic proficiency with high cold stability. The discovery of more flexible PH degrading strategies used by PHcB in colder environments could have a significant beneficial outcome on existing bioremediation technologies. Still, PHcB is least explored for other industrial and biotechnological applications as compared to non-PHcB psychrophiles. The present review highlights the pros and cons of the existing bioremediation technologies as well as the potential of different bioaugmentation processes for the effective removal of PH from the contaminated cold environment. Such research will not only serve to investigate the effects of pollution on the basic functional relationships that form the cold ecosystem but also to assess the efficacy of various remediation solutions for diverse settings and climatic conditions. [ABSTRACT FROM AUTHOR]

Massive quantitities of waste generated by rising human population and rapid urbanisation are often disposed of into open dumps or landfills. The leachates released from these dumpsites penetrate the soil and can alter the existing biotic communities of the soil. In soil, the microbial communities are the dominant drivers which undergo changes in community structure and diversity in response to the changes in their biotic and abiotic environment. The heterogeneous waste disposed in a dumpsite or a landfill releases leachate containing nutrients along with toxic chemicals and allochthonous microorganisms in the soil. How the microbial community structure and diversity changes in a landfill or a dumpsite soil receiving leachate from it are some important questions from the perspective of microbial ecology. To unravel the community structure of bacteria inthe soil receiving dumpsite leachate and to assess the disturbance diversity relationship in this site, a comparative metagenomic analysis of the soil receiving dumpsite leachate and that of the soil of an adjacent wetland (conserved under Ramsar convention) not receiving dumpsite leachate used as the reference point was done to observe the effect of waste dumping activity on microbial diversity. The microbial diversity of the soil receiving dumpsite leachate and that of the wetland soil were found to differ significantly. Higher microbial diversity was observed in the dumpsite soil, while the wetland soil showed relative dominance of a few microbial taxa. [ABSTRACT FROM AUTHOR]

Indo-Pacific corals predominantly reproduce using synchronous mass spawning events to maximise fertilisation. However, as disturbances continue to thin population densities, the quantities of gametes released declines and colonies become more isolated, reducing the likelihood of cross-fertilisation. Local hydrodynamic conditions can promote or inhibit gamete contact; thus, the interaction between the abiotic environment and sperm density will determine the amount of time gametes interact. In this study, we investigated the sensitivity of reproduction to manipulations of two key limiting factors of fertilisation: sperm concentration and contact time between gametes. We explored fertilisation kinetics of phylogenetically and functionally similar and diverse coral taxa on the Great Barrier Reef and Western Australia (Acropora digitifera, A. tenuis; Coelastrea aspera, Platygyra daedalea). Results indicate that fertilisation is optimised at sperm concentrations > 103 sperm mL−1 and contact times > 30 s, but the extent of these relationships is species-specific. All species showed clear differences in fertilisation success across contact times, although these differences were less distinct for A. tenuis and P. daedalea at very high sperm concentrations. Acropora digitifera and P. daedalea exhibited nonlinear trends with steep slopes of increased fertilisation success once sperm concentration surpassed values of 104 sperm mL−1 and 102 sperm mL−1, respectively, followed by slight declines. Acropora tenuis and A. digitifera had the highest maximum fertilisation success, likely owing to beneficial evolved functional traits like large egg sizes. The present analysis underpins studies of fertilisation kinetics in natural reef populations to help inform management and restoration practices that assist population resilience and recovery. [ABSTRACT FROM AUTHOR]

Large old trees, which provide ecosystem services and serve as a historical and cultural heritage, are exposed to various environmental threats, such as habitat fragmentation and climate change, necessitating diagnosis of tangible and intangible stresses and their effects on tree growth for effective management. This study investigated the photosynthetic characteristics of 25 large old Zelkova serrata (Thunb.) Makino trees in Chungcheong Province, Korea, and identified the physical environmental factors affecting their physiological responses. Maximum assimilation rate (Amax) was the highest in July (summer), transpiration rate (E) and stomatal conductance (gs) increased from May (spring) to September (fall), and water use efficiency (WUE) was the highest in May (spring) and decreased until September (fall). Amax decreased as tree height increased. Ambient CO2 and vapor pressure deficit (VPD) were negatively correlated with photosynthetic parameters throughout the growth season and in July (summer) and September (fall), respectively. Physical environmental factors exhibited complex effect on physiological activities, which increased with wide growth space and decreased with deep soil covering and high impervious ground surface ratio. Physiological responses differed with surface types within the growth space, with bare land showing higher mean Amax, E, and gs than areas with mulching material or concrete. This study quantitatively determined the physiological activities of large old Z. serrata and proposes appropriate management measures for ensuring their healthy growth in abiotic stress environment. [ABSTRACT FROM AUTHOR]

The United Nations Food Systems Summit and the European Green Deal have prompted various policy and regulatory initiatives aiming to transition agricultural practices to become more sustainable. An array of agricultural systems (e.g., regenerative, conservation agriculture, integrated crop management) have been lauded as potential solutions to improve food production sustainability. These systems use combinations of agricultural tools (e.g., crop rotation) to modify the crop environment to reduce weeds, pests and disease, alongside chemical (e.g., plant protection products) tools. Each tool has the potential to impact both the abiotic and biotic environment, with different combinations of tools having different overall outcomes. To improve the sustainability of agricultural practices it is important to understand, and where possible, quantify the environmental costs and benefits of the various tools that are applied within diverse cropping systems, as well as their potential interactions. While extensive literature exists, practical approaches are needed to cost-effectively synthesise key impacts and interactions to support decision making. A cost-effective methodology, adapting a rapid evidence assessment, was developed to review evidence and enable identification of the key environmental impacts for commonly applied agricultural tool options. The approach was applied to each tool individually (e.g., inversion tillage, crop rotation) to, where possible, isolate their specific impacts on the environment. Focused categories were assessed, considering biotic (insect, earthworms, etc.) and abiotic (soil, water, air quality, climate) impacts. This paper considers inversion tillage (also known as ploughing) as a case study to illustrate findings using the approach. Evidence is presented for direct and indirect impacts on the environment, selectivity of impacts and data gaps. The approach quickly provided robust evidence summaries of the key environmental implications of inversion tillage, facilitating identification of opportunities and trade-offs that can inform practice. The evidence highlighted how inversion tillage can offer effective weed control to reduce herbicide use, but carries increased risk to soil health, with connected implications for water, air and climate. This time-efficient review methodology can facilitate development of clear guidance to inform farmers in their decision making to improve on-farm sustainability, while serving as a useful starting point for conducting evidence reviews for policy development. [ABSTRACT FROM AUTHOR]

Soil-borne pathogens cause severe diseases in many crops around the world. Due to the harmful nature of the chemical pesticides used against such pathogens, extensive research has focused on developing sustainable solutions such as biocontrol agents. Nevertheless, the complex interaction of such agents with their biotic and abiotic environment is challenging. Filamentous cyanobacteria, the pioneers and main primary producers in biological soil crusts (BSC), show considerable tolerance to extreme environmental conditions within the crust. Soil inoculation with cyanobacteria is a promising practice for sustainable agriculture in drylands where high tolerant organisms is required. Nevertheless, its plant protection potential has been less explored. Cyanobacteria such as Leptolyngbya ohadii, a dominant species in the BSC of the northwest Negev desert, Israel, are known to produce a large array of secondary metabolites. Application of L.ohadii spent media severely inhibits the growth of various prokaryotes and eukaryotes. Its resilience and the observed antimicrobial activity thus make L.ohadii a promising candidate for the development of a biocontrol agent. However, little is known about the effect of environmental conditions on its antimicrobial activity. Here we examined the antifungal activity of L.ohadii on a range of soil-borne fungal pathogens. We assessed the effect of the daily hydration/dehydration cycle of its natural habitat on the expression of gene clusters for secondary metabolites production using a novel custom-made environmental conditions simulation chamber. Our data advance the understanding of the complex interaction of L.ohadii with its biotic and abiotic environment for application as a dryland biocontrol agent. [ABSTRACT FROM AUTHOR]

A challenging task to understand health and disease-related microbiome signatures is to move beyond descriptive community-level profiling towards disentangling microbial interaction networks. Using a synthetic gut bacterial community, we aimed to study the role of individual members in community assembly, identify putative keystone species and test their influence across different environments. Single-species dropout experiments reveal that bacterial strain relationships strongly vary not only in different regions of the murine gut, but also across several standard culture media. Mechanisms involved in environment-dependent keystone functions in vitro include exclusive access to polysaccharides as well as bacteriocin production. Further, Bacteroides caecimuris and Blautia coccoides are found to play keystone roles in gnotobiotic mice by impacting community composition, the metabolic landscape and inflammatory responses. In summary, the presented study highlights the strong interdependency between bacterial community ecology and the biotic and abiotic environment. These results question the concept of universally valid keystone species in the gastrointestinal ecosystem and underline the context-dependency of both, keystone functions and bacterial interaction networks. Here, characterizing a synthetic gut bacterial community, the authors reveal a context dependency of keystone functions and bacterial interaction networks, challenging the concept of universal keystone species in the gastrointestinal ecosystem. [ABSTRACT FROM AUTHOR]

Progress in understanding allelopathic interactions among plants has long been hampered by the complexity of the many direct and indirect interactions involved. Plant processes and growth are not only affected by allelochemicals but by resource limitations, pathogens, herbivores, and microbial interactions. Interference mechanisms frequently interact, and the magnitude of effects can depend on the plant's biotic and abiotic environment. The rhizosphere is chemically complex, with thousands of potentially bioactive allelochemicals produced by plants, microorganisms and soil invertebrates. The rhizosphere is also dynamic, in that concentrations of these metabolites vary as pulses of allelochemicals are released by plant roots and other organisms, as they leach from decaying plant material, as microorganisms degrade and sometimes transform allelochemicals, and as allelochemicals are taken up by plants, bind to soil components, or leach from the root zone. Recent advancements in instrumentation and technologies for the analysis of trace levels of chemical substances in soil, as well as the development of genomics, proteomics, and transcriptomics approaches allow researchers to probe both the biosynthesis of allelochemicals and plant responses to allelochemical exposures. These new technologies will provide much more detailed information on rhizosphere chemistry and about the production and response to metabolites by individual cells. This review describes case studies and current examples that illustrate how these new approaches and tools can enhance our understanding of allelopathic interactions, and argues that to truly advance our understanding of allelopathic interactions, these must be applied in ecologically rigorous and meaningful ways. [ABSTRACT FROM AUTHOR]

Intensive ungulate browsing significantly impacts forests worldwide. However, it is usually not single browsing events that lead to sapling mortality, but the little-researched interactions of browsed saplings with their biotic and abiotic environment. (I) Our objective was to assess the impact of ungulate browsing on the growth of young saplings relative to other environmental factors by utilizing their height increment as a sensitive measure of vitality to indicate their status. (II) Furthermore, we aimed to identify factors affecting ungulate browsing at our study sites, assessed as browsing probabilities, and identify effective mitigation measures for browsing impact. We analyzed an extensive sapling dataset of 248 wildlife exclosures, which were erected in 2016 in beech dominated forests across Germany and assessed annually until 2020. (I) Browsing probability and light availability were the most influential parameters for selectively browsed, admixed tree species (e.g., sycamore maple). Height increment showed abrupt setbacks, which caused a permanent collapse of growth when browsing exceeded a certain level. However, light availability enhanced height increment. (II) An increase in deer harvest reduced the browsing probability of selectively browsed species considerably. We conclude that the growth-inhibiting effect of ungulate browsing is a multifactorial phenomenon, which can be mitigated by silvicultural management and efficient hunting strategies. [ABSTRACT FROM AUTHOR]

Microbial communities in agricultural soils are fundamental for plant growth and in vineyard ecosystems contribute to defining regional wine quality. Managing soil microbes towards beneficial outcomes requires knowledge of how community assembly processes vary across taxonomic groups, spatial scales, and through time. However, our understanding of microbial assembly remains limited. To quantify the contributions of stochastic and deterministic processes to bacterial and fungal assembly across spatial scales and through time, we used 16 s rRNA gene and ITS sequencing in the soil of an emblematic wine-growing region of Italy. Combining null- and neutral-modelling, we found that assembly processes were consistent through time, but bacteria and fungi were governed by different processes. At the within-vineyard scale, deterministic selection and homogenising dispersal dominated bacterial assembly, while neither selection nor dispersal had clear influence over fungal assembly. At the among-vineyard scale, the influence of dispersal limitation increased for both taxonomic groups, but its contribution was much larger for fungal communities. These null-model-based inferences were supported by neutral modelling, which estimated a dispersal rate almost two orders-of-magnitude lower for fungi than bacteria. This indicates that while stochastic processes are important for fungal assembly, bacteria were more influenced by deterministic selection imposed by the biotic and/or abiotic environment. Managing microbes in vineyard soils could thus benefit from strategies that account for dispersal limitation of fungi and the importance of environmental conditions for bacteria. Our results are consistent with theoretical expectations whereby larger individual size and smaller populations can lead to higher levels of stochasticity. [ABSTRACT FROM AUTHOR]

Background: Climate change has escalated global environmental risks, particularly the effects of abiotic stresses on agricultural productivity. Improving crop plants' acclimation to abiotic stress environments is critical to cope with increasing incidences of abiotic stresses, which could potentially be attained by modifying adaptive physiological and molecular processes. Scope: The agricultural sector is coherently linked with nutrient input, and thus the judicious application of mineral elements as "stress combaters" could be expected to show ameliorative responses under such circumstances. Selenium (Se) has gained substantial recognition as a 'plant beneficial element' governing stress adaptive responses by modulating metabolic and signaling pathways associated with plant growth and developmental processes. Se-mediated abiotic stress-responsive and mechanistic behavior have achieved significant progression, however, still there are numerous unexplored facets needed to explore, which will add-on the current elucidative knowledge on the underlying phenomena. Although the individual roles of Se, plant hormones, and other signaling molecules have been comprehensively delineated, their intricate interplay with each other to govern plant responses to multiple abiotic stresses is still unnoticeable. Conclusions: The current review sheds light on the implicational approaches and underlying mechanisms of Se-induced plant developmental responses and tolerance to abiotic stresses, and its crosstalk with plant hormones and other signaling molecules in regulating the tolerance process. In the near future, it will be intriguing to explore further the diverse roles of Se with plant hormone signaling in the conflict between plants and environmental exposures. To understand this, the characterization and identification of key genes would be effective in exploring the intrinsic signaling mechanism of Se-PGR interaction to provide new insights into the complex signaling pathways to regulate stress resilience. [ABSTRACT FROM AUTHOR]

Plants can strongly influence the performance of subsequent conspecific and heterospecific plants either positively or negatively by conditioning soil abiotic and/or biotic properties via plant litter and root activity. Practical applications of plant-soil feedback Besides helping to understand plant community dynamics in natural ecosystems, knowledge about plant-soil feedback can be used for applied purposes (e.g., Mariotte et al. [23]). Next, using data from two previous plant-soil feedback studies, Rutten and Allan ([25]) demonstrated that their framework could substantially explain plant-soil feedback between species. Therefore, we advocate future studies to (re-) examine the influences of various external drivers on plant-soil feedback and their underlying processes, as well as experimentally validate novel methodological adaptations aiming to improve the estimation/prediction of plant-soil feedback effects. [Extracted from the article]

Interactions derived from social hierarchies are linked to the release of glucocorticoids, and the levels of this hormone may vary depending on the species’ reproductive strategy. In non-cooperative breeding species, dominant individuals have lower corticosterone levels compared to subordinates. The Andean Condor (Vultur gryphus) is the largest avian scavenger in South America and presents a social hierarchy system: males dominating over females and adults over immatures. Despite the large number of studies on the biology and ecology of the Andean Condor, the levels of corticosterone in the different age classes have not yet been evaluated. In this study, we compared corticosterone levels in shed feathers (CortFeather) of the Andean Condor by age classes (adult, subadult, and juvenile) over 4 years (2016–2019), covering two independent molting periods fitting a linear model (age classes*molting period). Because Andean Condor does not breed cooperatively, we expected lower levels of CortFeather in dominant adults compared to subordinates (subadults and juveniles). Contrary to our expectations, we observed a significant interaction between age classes and molting periods: adults in molting period 1 presented higher CortFeather levels than adults in molting period 2 and to subadults in molting period 2. The significant interaction we observed between age class and molting period suggests that the relationship between hormones and behavior in social species is not simple; both the social and abiotic environments influence. Since the hormone–behavior relationship is interdependent, studying it requires a solid understanding of the ecological and social context surrounding the subject. Thus, further research on hormone levels in relation to social systems—both with and without cooperative reproduction—is necessary. [ABSTRACT FROM AUTHOR]

The necessity of identifying a larger (than the biosphere) global ecosystem of geospheric rank—the ecosphere—has been substantiated. The boundaries of the ecosphere are determined, and they include all living matter of the planet, the atmosphere up to the thermosphere, the entire hydrosphere, and the upper part of the lithosphere with the metamorphic layer. Within this space, a great geological cycle is achieved, linking the biosphere and its abiotic environment into a unified whole and creating a specific form of its structural and functional organization. The great geological cycle of matter performs the function of a system-forming cyclic process in the ecosphere, which does not have complete closedness. The main factor controlling the degree of closedness of the geological cycle is the exchange of matter at the boundary between the lithosphere and the mantle. The processes of metamorphism occurring outside the biosphere constitute the mechanism of ecosphere organization, which has long supported life on Earth: they regenerate the products of biospheric metabolism and ensure their return to the biosphere in forms available for reconsumption by living organisms. One characteristic feature of the ecosphere space is the redox nonequilibrium caused by the activity of living organisms. In the ecosphere, a complete life cycle takes place from the formation of living organisms from mineral components to complete transformation into the initial mineral components of living matter and all products of biospheric metabolism. Outside the ecosphere there are neither living organisms nor products of their vital activity that have retained the thermodynamic nonequilibrium acquired in the biosphere. [ABSTRACT FROM AUTHOR]

Groundwater is essential for drinking as well as irrigation purposes. The occurrence of microplastics (MPs) in the biotic and abiotic environments is widely recorded, but little is known about MP occurrence in groundwater. This study assessed MP contamination and hydrochemical quality in a shallow and unconfined aquifer of Tuticorin, India. Water samples were collected from bore wells and open wells for MP assessment and hydrochemical analysis. All the physicochemical parameters are within defined limits, and the significant variations observed could be due to rock–water interaction and the mixing of seawater and freshwater. MPs are found in groundwater samples with an average abundance of 29.73±3.27 items per liter (range 9–39 items per liter), whereas the mean MP abundance is found to be higher in bore wells (32.9±4 items per liter) than in open wells (23.9±3.56 items per liter). The dominant type of MPs observed are fibers and the colors are red, black and white with a predominant size <3 mm. Results of a hazard assessment (polymer hazard index, PHI) on the MPs place the samples under the hazard level IV category due to the presence of high-hazard-score polymers such as polyamide, polystyrene and polyurethane. No significant correlation is noted between the groundwater quality and the quantity of MPs. The presence of MPs in the groundwater could be due to infiltration from surface sources of plastic pollution and could also result from the mixing of seawater and freshwater. Further study is necessary to identify the sources of MP contamination and to assess the capacity of MPs to infiltrate the aquifer. [ABSTRACT FROM AUTHOR]

Cover crops are increasingly being used in ecological restoration projects, and are hypothesized to facilitate establishment of sown species by reducing weed abundances without competing with the target mix. We tested these predictions and examined the role of cover crop species on later species composition and diversity using cover crop seed treatments. Treatments included a fall seeding of one annual (Raphanus sativus or Avena sativa), one biennial (Oenothera biennis), one perennial species (Elymus canadensis), two grass-forb species combinations, or nothing as a control. All plots received the same diverse tallgrass prairie seed mix in March of the following year. Plant communities were sampled through five growing seasons. We found that cover crop treatments influenced community assembly, and that cover crop species varied in their effectiveness at reducing weed abundances, with the perennial grass E. canadensis being especially effective at reducing weeds. After 5 years, treatments were neutral in their effects on species diversity. However, composition of establishing plants (not including the cover crop) differed significantly among cover crop treatments on all sampling dates, indicating that treatments had long-term effects. Plots containing the C3 grass E. canadensis had greater abundance of C3 grasses and forbs, and reduced C4 grass abundance compared to other treatments. Our results indicate that cover crop species differ in their effects on assembling tallgrass prairie communities and that niche modification (i.e., species altering the abiotic environment in a way that favors species that benefit from the alterations) occurs when the cover crop is a perennial grass. [ABSTRACT FROM AUTHOR]

Aims: Environmental heterogeneity can influence biological invasions by altering the interspecific competition between native and invasive species. Soils are a key component of the abiotic environment that can vary in small scales. However, it is not clear how the mechanisms that patch size of soil heterogeneity mediates competition between native and invasive plants. Methods: We grew invasive Rhus typhina and native Rhus chinensis in intraspecific (two seedlings of the same species per pot) and interspecific competition (one seedling of each of the two species per pot) with three different soil treatments: homogeneous (Ho) and two soil heterogeneous (He1 and He2) treatments. In He1 and He2 treatments, the soil consisted of loam and peat patches but different patch sizes, and in Ho treatment, the soil was a uniform mixture of the two types of soil patches. Results: We found R. typhina had greater overall performance and belowground investment compared to R. chinensis and outcompeted R. chinensis in the interspecific competition regardless of soil heterogeneity. The strength of interspecific competition increased with increasing soil heterogeneity, such that soil heterogeneity amplified the superiority of R. typhina over R. chinensis. Moreover, R. chinensis were more plastic in phenotype than R. typhina, indicating phenotypic plasticity did not confer advantages to R. typhina over R. chinensis across various soil heterogeneity. Conclusions: Soil heterogeneity can facilitate the invasion of R. typhina by enhancing the advantages over R. chinensis and altering interspecific competition. Phenotypic divergence rather than plasticity plays an important role in mediating interspecific competition. [ABSTRACT FROM AUTHOR]

The European Landscape Convention aims to promote landscape protection, management and planning. This must be done based on identification and knowledge of those basic landscape types that were created by the interaction of human and nature over the course of historical development. This paper presents a methodological approach for creation and evaluation of representative biocultural types of landscape, in order to elaborate an effective strategy for landscape protection, and proposes a management strategy of sustainable use of representative biocultural landscapes of Slovakia. That will ensure the regular maintenance of the landscape in view of current global trends and factors affecting the landscape. Our interdisciplinary approach is based on previous landscape classifications and the interaction of natural and cultural elements. The classification of the biocultural landscape is obtained as a result of multi-criteria analysis in GIS and synthesis of maps of potential vegetation, real ecosystems and current land use, abiotic conditions of representative geoecosystems of Slovakia, and other specific statistical data. We assessed the perception and significance of individual landscape types by way of a questionnaire survey. In Slovakia, seven basic types of landscape were singled out, ranging from natural to semi-natural to anthropogenic, within which other subtypes were specified. We assessed the protection of individual types, as well as threats and degradation of the landscape. Insufficient protection is given to the most valuable types of biocultural landscape and new tools and methods of support and protection have to be implemented. [ABSTRACT FROM AUTHOR]

Because of global land surface warming, heavy metal toxicity is expected to occur more often and more intensely, affecting the growth and development of the major cereal crops such as maize (Zea mays L.) in several ways, thus affecting the production component of food security. Hence, it is important to know the best cultivars of Z. mays in abiotic stress environment to fulfill the market demand of this staple food. For this purpose, we investigate the present study to find the best Z. mays cultivar to be grown in chromium (Cr)-contaminated sand (200 µM). In this experiment, we have studied 10 cultivars (Malka, Sadaf, Pearl, CZP, YY, YH, MMRI-yellow, Sahiwal, EV-20, and EV-77) of Z. mays grown in plastic pots for 4 weeks (in addition with seed germination) under Cr − (0 µM) and Cr + (200 µM) in sand medium. Based on the findings of the current experiment, we illustrated that Cr toxicity induced a significant (P < 0.05) reduction in shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight and root dry weight, chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid content and induced oxidative damage to membrane-bounded organelles by increasing the malondialdehyde and hydrogen peroxide which were manifested by flavonoid and phenolic contents. Moreover, Cr uptake was also higher in the plants grown in the Cr-contaminated sand compared to the plants grown without the Cr-contaminated sand. We also noticed that Pearl, CZP, and Sahiwal cultivars are suggested to be Cr-tolerant cultivars as showed better growth and development in Cr-contaminated sand while Sadaf, MMRI, and EV-77 showed lower growth and composition in Cr-contaminated sand. The overall pattern of Z. mays cultivars grown in Cr-contaminated sand is as follows: Pearl > CZP > Sahiwal > YY > YH > EV-20 > Malka > EV-77 > MMRI-yellow > Sadaf. Conclusively, it can be identified that when grown in Cr-contaminated sand, Pearl, CZP, and Sahiwal have greater ability to grow in polluted soils. Overall, Z. mays cultivars showed better growth in Cr-stressed environment due to defense mechanism but further experiments needed to be conducted on molecular level. [ABSTRACT FROM AUTHOR]

Predicting which species will present (or absent) across geographical regions, and where, remains one of the important issues in ecology. From a methodical viewpoint, one of the concerns in examining species presence–absence across an environmental gradient is about the robustness of model-based predictions, which are given by distinct modelling frameworks used. Generally, different complexities and ecological factors are incorporated into such models, e.g. abiotic environments, spatial dispersal process, and stochasticity. Motivated by these ecological issues, we revisit a single-species logistic growth problem by employing stochastic agent-based model (ABM) and deterministic system and extend these frameworks to incorporate the effects of spatially changing environments. We observe that our ABM, which is formulated using random walk theory and birth–death process, demonstrates important qualitative behaviours that are consistent with the underlying theories of stochastic process. The results of ABM with large population sizes also agree with those of the deterministic equation. However, some discrepancies are observed when the population size is small. The ABM densities seem to underestimate the deterministic solutions, which illustrate the effects of stochasticity on small populations with some individuals may go extinct simply by chance. To quantify the underestimation of ABM as opposed to deterministic predictions, we employ certain probabilistic techniques: while the means of quasistationary probabilities distribution appear to give a counterintuitive prediction particularly near the edge of species ranges, the expected values given by state probabilities distribution are in agreement with the ABM densities observed for small population sizes across spatial locations. These salient observations depict emergent behaviours of stochastic ABM, which can contribute to additional insights on the dynamics of ecological species. It also shows how such small-scale interactions coupled with local dispersal and spatial phenomena occurring at a microscopic level can affect macroscopic-level dynamics. As such, comparing and contrasting the dynamics of different models can help in understanding the generality of ecological results and may offer important insights into the robustness of model-based predictions of species presence–absence. [ABSTRACT FROM AUTHOR]

Background: Bioaccumulation of hydrophobic organic compounds (HOCs) along freshwater food chains is a major environmental concern as top predators in food webs are relevant for human consumption. To characterize and manage the associated risks, considerable numbers of organisms are sampled regularly for monitoring purposes. However, ethical and financial issues call for an alternative, more generic and more robust approach for assessing the internal exposure of fish that circumvents large variability in biota sampling due to interindividual differences. Passive sampling devices (PSDs) offer a fugacity-based approach for pollutant enrichment from different abiotic environmental compartments with a subsequent estimation of bioaccumulation in fish which we explored and compared to HOC concentrations in fish as determined using traditional approaches. Results: In this study, concentrations in silicone-based PSDs applied to the water phase and suspended particulate matter (SPM) of a river polluted with HOCs were used to estimate the concentration in model lipids at thermodynamic equilibrium with either environmental compartment. For comparison, muscle tissue of seven fish species (trophic level 1.8 to 2.8) was extracted using traditional exhaustive solvent extraction, and the lipid-normalized concentrations of HOCs were determined. The PSD-based data from SPM proved to be a more conservative estimator for HOCs accumulated in fish than those from water. Body length of the fish was found to be more suitable to describe increasing accumulation of HOCs than their trophic level as derived from stable isotope analysis and might offer a suitable alternative for future studies. Conclusions: By combining fugacity-based sampling in the abiotic environment, translation into corresponding concentrations in model lipids and body length as an indicator for increasing bioaccumulation in fish, we present a suggestion for a robust approach that may be a meaningful addition to conventional monitoring methods. This approach potentially increases the efficiency of existing monitoring programs without the need to regularly sacrifice vertebrate species. [ABSTRACT FROM AUTHOR]

Phylogenies are crucial for understanding historical patterns of genetic biodiversity, but very few are incorporated practically into existing conservation programs. Xishuangbanna, a tropical–subtropical forest transition, is a key biodiversity hotspot in Southwest of China; however, gaps between practical protection and national planning need to be bridged, as ongoing, rapid expansion of rubber plantations in the region increasingly threatens local diversity. Here, we used administrative regions as study units to identify spatial patterns for 158 threatened woody species and investigate the ratio of tropical floristic to temperate floristic in the transition zone. We used all-subsets regression analysis to test the impacts of environments (climatic, edaphic, topographic) on biodiversity patterns. Spatial patterns using several conservation metrics gave different results, with species richness, phylogenetic diversity, and evolutionary distinctiveness and global endangerment highly consistent spatially, while either standardized phylogenetic diversity and phylogenetic structure performed differently from others for spatial patterns. The biodiversity patterns of threatened woody species in Xishuangbanna are affected by the combined impact of rubber plantations and abiotic environments, but their evolutionary history is not, with only c. 69% of phylogenetic diversity currently protected by traditional nature reserves. Although the Menglong and Xiangming townships show high conservation values, they are not in the reserves. Eleven threatened woody species were required for ex situ conservation due to threats from clearance for rubber plantations and in all, 21 regionally and internationally important species are currently unprotected. We recommend incorporating the phylogenetic component of biodiversity in improving current and establishing new reserves. [ABSTRACT FROM AUTHOR]

Microbial communities, like their macro-organismal counterparts, assemble from multiple source populations and by processes acting at multiple spatial scales. However, the relative importance of different sources to the plant microbiome and the spatial scale at which assembly occurs remains debated. In this study, we analyzed how source contributions to the foliar fungal microbiome of a C4 grass differed between locally abundant plants and soils across an abiotic gradient at different spatial scales. Specifically, we used source-sink analysis to assess the likelihood that fungi in leaves from Panicum hallii came from three putative sources: two plant functional groups (C4 grasses and dicots) and soil. We expected that physiologically similar C4 grasses would be more important sources to P. hallii than dicots. We tested this at ten sites in central Texas spanning a steep precipitation gradient. We also examined source contributions at three spatial scales: individual sites (local), local plus adjacent sites (regional), or all sites (gradient-wide). We found that plants were substantially more important sources than soils, but contributions from the two plant functional groups were similar. Plant contributions overall declined and unexplained variation increased as mean annual precipitation increased. This source-sink analysis, combined with partitioning of beta-diversity into nestedness and turnover components, indicated high dispersal limitation and/or strong environmental filtering. Overall, our results suggest that the source-sink dynamics of foliar fungi are primarily local, that foliar fungi spread from plant-to-plant, and that the abiotic environment may affect fungal community sourcing both directly and via changes to host plant communities. [ABSTRACT FROM AUTHOR]

There is a worldwide concern to achieve food security with a sustainable approach, including the generation and implementation of techniques for the production of high-quality chemical-free crops. This food revolution has promoted the development and consolidation of programmes for integrated pest management. Some of those programmes include the use of diverse organisms (biological control agents) to suppress populations of pests potentially harmful to the crops. Among these biological control agents are entomopathogenic fungi that are highly effective in suppressing a diversity of insects and have, therefore, been produced and marketed throughout the world. However, the bottleneck for applying entomopathogenic fungi is the production of propagules (blastospores and conidia) with resistance to environment conditions and abiotic factors, maintaining high quality in terms of virulence. Therefore, this manuscript presents recent studies related to increasing resistance and quality using different bioreactors to produce conidia. The above presents a global panorama related to current developments that contribute to improving the resistance, quality, and production of entomopathogenic fungal propagules. [ABSTRACT FROM AUTHOR]

Ecosystem engineers often exert strong effects on the recruitment of other species through modification of the local abiotic and biotic environment. In 2015, artificial reefs in eastern Tasmania (− 42.64693, 148.01481) spanning seven different patch sizes (0.12–7.68 m2) and supporting four densities of transplanted kelp (Ecklonia radiata at 0, 4.1, 8.2 and 16.4 kelp m−2) were used to determine how the patch size and density of this ecosystem engineer influenced the recruitment of microphytobenthic (MPB) algae, and a secondary ecosystem engineer, the mussel Mytilus galloprovincialis. Increasing kelp density and patch size inhibited the establishment of subcanopy MPB algae on settlement slides and reduced the recruitment of mussels in standardised rope fibre habitats (RFHs). The productivity:biomass ratio (P:B) of mussel recruits tended to be lower on small reefs and reefs without kelp, relative to larger reefs with high densities of kelp. Canopy shading and reduced cover of turf algae appeared to negatively impact the recruitment of MPB algae and mussels, whilst reduced sediment accumulation on the reefs due to the kelp was also negatively associated with mussel recruitment. These findings highlight the role of ecosystem engineering by kelp in inhibiting the establishment of other species which may additionally impact community dynamics and primary and secondary productivity. The limited capacity of small kelp patches to inhibit the recruitment of other organisms supports the notion that fragmented patches of ecosystem engineers could be more suspectable to adverse outcomes from species interactions making them less resistant to shifts towards an alternative ecosystem state. [ABSTRACT FROM AUTHOR]

The roots and rhizospheres of trees harbor diverse microbial communities that can modulate plant competition and facilitation, thereby influencing plant community dynamics. Understanding the factors structuring microbial communities is valuable for predicting how plant communities assemble. In temperate forests, host identity, biotic neighborhood, abiotic environment and geographic distance shape microbial communities, but the importance of these factors is less well studied in highly diverse tropical forests. In this study, we used high-throughput amplicon sequencing to characterize the arbuscular mycorrhizal fungal (AMF) and rhizosphere bacterial (RB) communities of five tree species in an 8-year-old common garden planted into the understory of a selectively logged old-growth forest in Malaysian Borneo. We assessed the influence of host tree species, host traits and neighboring tree identity on the composition and diversity of both communities. The AMF and RB communities differed amongst host tree species; the tree species with the most distinct AMF communities associated with the lowest diversity of AMF. Alpha diversity of AMF correlated negatively with leaf phosphorus and potassium content. Density and abundance of AMF neighbor trees growing near focal trees influenced AMF community composition and was positively correlated with RB alpha diversity. Our results highlight the importance of considering both host tree identity and biotic neighborhood of trees in studies of microbial communities in tropical forests. Important next steps will be to elucidate the functional significance of shifts in AMF and RB community compositions and their implications for community and ecosystem dynamics in tropical forests. [ABSTRACT FROM AUTHOR]

The interplay between organisms with their abiotic environment may have profound effects within ecological networks, but are still poorly understood. Soil physical ecosystem engineers (EEs) modify the abiotic environment, thereby potentially affecting the distribution of other species, such as microarthropods. We focus on three co-occurring physical EEs (i.e. cattle, vegetation, macrodetritivore) known for their profound effect on soil properties (e.g. pore volume, microclimate, litter thickness). We determined their effects on Collembola community composition and life-form strategy (a proxy for vertical distribution in soil) in a European salt marsh. Soil cores were collected in grazed (compacted soil, under short and tall vegetation) and non-grazed areas (decompacted soil, under short and tall vegetation), their pore structure analysed using X-ray computed tomography, after which Collembola were extracted. Collembola species richness was lower in grazed sites, but abundances were not affected by soil compaction or vegetation height. Community composition differed between ungrazed sites with short vegetation and the other treatments, due to a greater dominance of epigeic Collembola and lower abundance of euedaphic species in this treatment. We found that the three co-occurring EEs and their interactions modify the physical environment of soil fauna, particularly through changes in soil porosity and availability of litter. This alters the relative abundance of Collembola life-forms, and thus the community composition within the soil. As Collembola are known to play a crucial role in decomposition processes, these compositional changes in litter and soil layers are expected to affect ecosystem processes and functioning. [ABSTRACT FROM AUTHOR]

A key problem in ecology is to predict the presence/absence of species across a geographical region. Addressing this problem in a multi-species community with priority effects (i.e., initial abundances determine the presence/absence of species) is a challenging task because species presence/absence depends on many factors such as abiotic environments, biotic interactions (i.e., interactions among species) and dispersal process. While various ecological factors have been considered, less attention has been given to the problem of understanding how dimensionality of space, in interaction with other factors, shape community assembly in the presence of priority effects. In this paper, we employ partial differential equations models (in one- and two-dimensional space) to examine the consequences of different dimensionality of space on the occurrence of priority effects and species coexistence in multi-species communities. We discover that as well as a pronounced increase in system complexity, adding a second space dimension essentially modifies the strength of priority effect. It is also observed that more outcomes with multi-species coexistence emerge as dimensionality of space is increased. As such, incorporating dimensionality in an ecological system with heterogeneous environments could engender additional insights on species coexistence mechanisms (as compared to just adding an extra dimension in the case of purely homogeneous space). These effects will strongly depend on how each interacting species responds to the environmental gradients. Overall, this study is among the first to explicitly show that combinations of distinct abiotic factors can shape the distributions of multiple competing species that are different from those in single abiotic factor case, and some dispersing species may respond to complex sets of abiotic and biotic conditions in variable ways. [ABSTRACT FROM AUTHOR]

Epibiotic species and epibiotic communities are heterogeneously distributed among individuals and body parts and habitats. They have a profound ecological impact, since the presence of epibionts affects the fitness of basibionts directly as well as indirectly, by modulating its interactions with the abiotic and biotic environment. In this article we assess the composition, alpha and beta diversity of epizoic macroalgae on crustaceans. Alpha diversity of epizoic macroalgae was determined for each of the basibionts as the effective number of species (qD). We proceeded with the correlation methodology Olmstead-Tukey to determine the hierarchical organization. On the shallow coast of the province of Santiago de Cuba, 24 epizoic macroalgae were found on the exoskeletons of six species of crustaceans. The hierarchical position of epizoic macroalgae in crustaceans is characterized by a predominance of rare species, followed by dominant, occasional and finally constant taxa. The greatest richness and diversity of epizoic macroalgae species was found on majoid crustaceans, which have active a masking behavior. The highest values of species richness, alpha and beta diversity of epizoic macroalgae were found in crustaceans with active camouflage. The fact that beta diversity is determined by the replacement of species reinforces the idea that these crustaceans use macroalgal assemblages to camouflage themselves. [ABSTRACT FROM AUTHOR]

Herbivory can have strong impacts on greenhouse gas fluxes in high-latitude ecosystems. For example, in the Yukon-Kuskokwim (Y-K) Delta in western Alaska, migratory goose grazing affects the magnitude of soil carbon dioxide (CO2) and methane (CH4) fluxes. However, the underlying drivers of this relationship are unclear, as few studies systematically tease apart the processes by which herbivores influences soil biogeochemistry. To examine these mechanisms in detail, we conducted a laboratory incubation experiment to quantify changes in greenhouse gas fluxes in response to three parameters altered by herbivores in situ: temperature, soil moisture content, and nutrient inputs. These treatments were applied to soils collected in grazing lawns and nearby ungrazed habitat, allowing us to assess how variation in microbial community structure influenced observed responses. We found pronounced differences in both fungal and prokaryotic community composition between grazed and ungrazed areas. In the laboratory incubation experiment, CO2 and CH4 fluxes increased with temperature, soil moisture, and goose fecal addition, suggesting that grazing-related changes in the soil abiotic environment may enhance soil C losses. Yet, these abiotic drivers were insufficient to explain variation in fluxes between soils with and without prior grazing. Differences in trace gas fluxes between grazed and ungrazed areas may result both from herbivore-induced shifts in abiotic parameters and grazing-related alterations in microbial community structure. Our findings suggest that relationships among herbivores and soil microbial communities could mediate carbon-climate feedbacks in rapidly changing high-latitude ecosystems. [ABSTRACT FROM AUTHOR]

Changes in plant abiotic environments may alter plant virus epidemiological traits, but how such changes actually affect their quantitative relationships is poorly understood. Here, we investigated the effects of water deficit on Cauliflower mosaic virus (CaMV) traits (virulence, accumulation, and vectored-transmission rate) in 24 natural Arabidopsis thaliana accessions grown under strictly controlled environmental conditions. CaMV virulence increased significantly in response to water deficit during vegetative growth in all A. thaliana accessions, while viral transmission by aphids and within-host accumulation were significantly altered in only a few. Under well-watered conditions, CaMV accumulation was correlated positively with CaMV transmission by aphids, while under water deficit, this relationship was reversed. Hence, under water deficit, high CaMV accumulation did not predispose to increased horizontal transmission. No other significant relationship between viral traits could be detected. Across accessions, significant relationships between climate at collection sites and viral traits were detected but require further investigation. Interactions between epidemiological traits and their alteration under abiotic stresses must be accounted for when modelling plant virus epidemiology under scenarios of climate change. [ABSTRACT FROM AUTHOR]

Small variations in environmental parameters can substantially alter species composition, but the extent to which different species respond to these changes remains obscure. A synoptic survey of seagrass-associated faunal communities was performed across the Gulf of Mexico using otter trawls coupled with seagrass and water quality assessments. The abundance of eight central seagrass inhabitants, representing a range of functional groups, were quantified to identify factors that best predicted their prevalence across environmental gradients and the consistency of these ecological relationships. Seagrass density and drift algal biomass generally had the strongest influence on animal abundance (40–67%), although relationships with drift algae were species specific and seemingly related to faunal size and mobility. Abundances of free-swimming pinfish, pigfish, and silver perch were negatively related to drift algae biomass (0.7, 0.7, and 1.0% Δ per 1 g·m−2 drift algae, respectively), whereas the abundance of pipefish (Syngnathus spp.) and brown/pink shrimp (Penaeus spp.) tended to be positively related to algal biomass (0.8 and 1.6% Δ per 1 g·m−2 drift algae). Shrimp abundances increased by 3.6% per 1% increase in light attenuation while the abundance of a higher-order visual predator, silver perch, negatively responded to light attenuation (1.1% Δ per 1% Δ vertical light attenuation). Additionally, bivariate plots of organismal abundance and salinity or canopy height indicated a unimodal relationship with peaks in abundance associated with intermediate values for several species. This study explored the extent species and functional groups responded to variation in key elements of the abiotic and biotic environment, providing insight into community development and offering resource managers quantitative targets for aspects of habitat quality. [ABSTRACT FROM AUTHOR]

Environmental factors play a significant role in controlling growth, development and defense responses of plants. Changes in the abiotic environment not only significantly alter the physiological and molecular pathways in plants, but also result in attracting the insect pests that carry a payload of viruses. Invasion of plants by viruses triggers the RNA silencing based defense mechanism in plants. In counter defense the viruses have gained the ability to suppress the host RNA silencing activities. A new paradigm has emerged, with the recognition that plant viruses also have the intrinsic capacity to modulate host plant response to environmental cues, in an attempt to favour their own survival. Thus, plant–virus interactions provide an excellent system to understand the signals in crosstalk between biotic (virus) and abiotic stresses. In this review, we have summarized the basal plant defense responses to pathogen invasion while emphasizing on the role of RNA silencing as a front line of defense response to virus infection. The emerging knowledge indicates overlap between RNA silencing with the innate immune responses during antiviral defense. The suppressors of RNA silencing serve as Avr proteins, which can be recognized by the host R proteins. The defense signals also function in concert with the phytohormones to influence plant responses to abiotic stresses. The current evidence on the role of virus induced host tolerance to abiotic stresses is also discussed. [ABSTRACT FROM AUTHOR]

Plant growth-promoting bacteria (PGPB), possess multifarious beneficial traits and facilitate plant growth by both direct and indirect mechanisms under hostile conditions. The objective of the current study was to evaluate the potential application of 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase) producing plant-growth promoting endophyte bacterium (PGPEB) Kocuria rhizophila strain 14ASP (National Center for Biotechnology Information; NCBI) Accession Number: LFIY00000000.1) heavy metals and salt resistance tolerance under hostile environment. The in vitro study was conducted to evaluate plant growth promotion characteristics, heavy metal and salt resistance of the K. rhizophila under normal and stressful environments. The strain 14ASP revealed the plant-growth promoting and of AAC deaminase activities under abiotic stress environment. K. rhizophila showed significant tolerance against different heavy metals on LB (Luria Ber-tani) agar plates and broth medium supplemented with cadmium (Cd), (50 mg L−1), cooper (Cu), (50 mg L−1), nickel (Ni), (50 mg L−1), lead (Pb), (200 mg L−1) and chromium (Cr) (500 mg L−1), respectively. It also exhibited population density (OD = 0.31–0.45) at different concentrations of sodium chloride (NaCl) (0% 5%, 10%, and 15% w/v) in LB medium. The draft genome of strain 14ASP is 2.6 Mb and was assembled into 183 contigs with 2689,1 bp and a G + C content of 70% and 1,882,646 bp, encoded 2409 protein, 8 rRNAs and 46 tRNAs. Genome analysis identified genes, involved in hydrocarbon metabolism, heavy metal tolerance, biofilm formation, Indole Acetic Acid (IAA) and siderophore biosynthesis. All these properties were confirmed by in silico and draft genome analysis. [ABSTRACT FROM AUTHOR]

Seasonal life history events are often interdependent, but we know relatively little about how the relationship between different events is influenced by the abiotic and biotic environment. Such knowledge is important for predicting the immediate and evolutionary phenological response of populations to changing conditions. We manipulated germination timing and shade in a multi-factorial experiment to investigate the relationship between spring and autumn phenology in seedlings of the pedunculate oak, Quercus robur, and whether this relationship was mediated by natural colonization of leaves by specialist fungal pathogens (i.e., the oak powdery mildew complex). Each week delay in germination corresponded to about 2 days delay in autumn leaf senescence, and heavily shaded seedlings senesced 5–8 days later than seedlings in light shade or full sun. Within seedlings, leaves on primary-growth shoots senesced later than those on secondary-growth shoots in some treatments. Path analyses demonstrated that germination timing and shade affected autumn phenology both directly and indirectly via pathogen load, though the specific pattern differed among and within seedlings. Pathogen load increased with later germination and greater shade. Greater pathogen load was in turn associated with later senescence for seedlings, but with earlier senescence for individual leaves. Our findings show that relationships between seasonal events can be partly mediated by the biotic environment and suggest that these relationships may differ between the plant and leaf level. The influence of biotic interactions on phenological correlations across scales has implications for understanding phenotypic variation in phenology and for predicting how populations will respond to climatic perturbation. [ABSTRACT FROM AUTHOR]

The goal of this paper is to assess the current status and trends of total mercury (THg) contamination of the atmosphere and terrestrial ecosystems in Poland. The study shows that the reduced domestic and worldwide atmospheric emission of Hg resulted in decreased THg level in the terrestrial biotope and biosphere. Considering that Poland is one of the main Hg emitters in Europe, the THg concentrations in its abiotic environment are still elevated. However, the THg level in terrestrial organisms is relatively low, which is because a large proportion of Hg deposited on land is accumulated in organic-rich soils. Regarding the THg concentration, consumption of wildlife and livestock from Poland is safe for humans. Nevertheless, the authors indicate the need for effective environmental monitoring, based on selected bioindicators, which is crucial considering the slowing reduction of Hg emission combined with the consequences of the changing climate. [ABSTRACT FROM AUTHOR]

In arid environments, shade provided by vegetation forms the crux of many facilitation pathways by providing other organisms with relief from high levels of solar radiation and extreme temperatures. Shade is an important determinant that structures arid ecosystem processes and functioning. While shade is considered an essential refuge for many organisms in arid environments, few studies have assessed how parasitic plants such as aerial mistletoes can influence the quality of shade provided by its host, and how this can subsequently influence species interactions. Here, we investigate how mistletoe influences the microclimate and daytime use of sub-canopy habitat by a large herbivore that seeks out shady micro-habitats to avoid daytime heat in Australia's Strzelecki Desert. We experimentally removed the pale-leaved mistletoe (Amyema maidenii) from mulga trees (Acacia aneura) and monitored sub-canopy ambient temperatures and the daytime use of sub-canopy habitat by red kangaroos (Osphranter rufus). Results showed that average hourly temperature during the daytime and daily maximum temperature were cooler and that kangaroos were approximately three times more likely to shelter beneath trees where mistletoe was present (control) compared to where mistletoes had been removed (treatment). By showing that mistletoe can improve the quality of shade provided by their host trees, our study offers a novel insight into how mistletoes can facilitate the surrounding biota through modifying the abiotic environment beyond its physical structure. More broadly, the results of our study emphasise the prevalence of positive interactions within ecological communities and how they can occur in unexpected ways and indirectly between organisms that never come into direct contact. [ABSTRACT FROM AUTHOR]

Animals can form groups for various reasons including safety from predators, access to potential mates and benefits of allo-parental care. However, there are costs associated with living in a group such as competition for food and/or mates with other members of the group, higher chances of disease transmission, etc. Group size dynamics can change with the biotic and abiotic environment around individuals. In the current study, we explored the links between group size dynamics and intestinal parasites of Indian peafowl (Pavo cristatus) in the context of seasons and food provisioning. Data for group size was collected across three seasons (pre-monsoon, monsoon and post-monsoon) at three field sites (Morachi Chincholi, Nashik and Rajasthan). Individual and group sightings of peafowl were noted down along with group size and composition (no. of males, females, adults, juveniles and sub-adults). Faecal samples were collected from food provision and non-provision areas across the same three seasons at same field sites. Parasite load in the samples was quantified using microscopic examination. Group size was significantly higher in pre-monsoon season as compared with monsoon and post-monsoon seasons. Monsoon and post-monsoon seasons had higher intestinal parasite prevalence and load as compared with pre-monsoon season. Thus, group size and intestinal parasites of Indian peafowl have an inverse relationship across seasons. Parasite load was significantly greater at food provision sites as compared with non-provision sites while parasite prevalence was comparable. Aggregation of individuals at the food provision sites may influence the parasite transmission and group-size dynamics in Indian peafowl. In conclusion, Indian peafowl are behaviourally plastic and fission-fusion of social groups may allow them to tackle ecological pressures such as predation and parasite transmission in different seasons. [ABSTRACT FROM AUTHOR]

Screening species-rich communities for the variation in functional traits along environmental gradients may help understanding the abiotic drivers of plant performance in a mechanistic way. We investigated tree leaf trait variation along an elevation gradient (1000–3000 m) in highly diverse neotropical montane forests to test the hypothesis that elevational trait change reflects a trend toward more conservative resource use strategies at higher elevations, with interspecific trait variation decreasing and trait integration increasing due to environmental filtering. Analysis of trait variance partitioning across the 52 tree species revealed for most traits a dominant influence of phylogeny, except for SLA, leaf thickness and foliar Ca, where elevation was most influential. The community-level means of SLA, foliar N and Ca, and foliar N/P ratio decreased with elevation, while leaf thickness and toughness increased. The contribution of intraspecific variation was substantial at the community level in most traits, yet smaller than the interspecific component. Both within-species and between-species trait variation did not change systematically with elevation. High phylogenetic diversity, together with small-scale edaphic heterogeneity, cause large interspecific leaf trait variation in these hyper-diverse Andean forests. Trait network analysis revealed increasing leaf trait integration with elevation, suggesting stronger environmental filtering at colder and nutrient-poorer sites. [ABSTRACT FROM AUTHOR]

Cuticular waxes are the covering of the outer layer of the plant, consist of hydrocarbon appears like whitish film or bloom in plant organs. They play a vital role like a safeguard from different stress condition in the plant. Since environmental factors are active regulators of cuticular wax biosynthesis, composition, quantity, and deposition, it is evident that cuticular wax is associated with plant stress responses. The diversity of cuticular wax compositions is a proof of the wealth of genes associated in plant wax production. Moreover, a number of wax genes were distinguished in plant/crops at abiotic stress conditions but, regulation of control of those wax genes has not been studied very well in major crop plants at abiotic conditions. A very few transcriptions factors were identified to regulate the expression level of wax genes of cuticular wax biosynthesis at abiotic stress condition. However, further study is needed to identify more candidate transcriptional regulation factors to cuticular wax production in different crop plants in diverse abiotic environments. Therefore, regulation of cuticular wax production under diverse abiotic stresses and the role of transcription factors into the plant cuticular wax accumulation will be helpful to engineer crop plants and improve transgenic crops for stress tolerance. In this review, we focused on a new perspective on transcriptional factors to regulate functional genes of cuticular wax biosynthesis in plants at abiotic stresses. [ABSTRACT FROM AUTHOR]

The occurrence of different color patterns in a population of a species can depend on genetic variations or plasticity to environmental conditions. Body color variation is under selection because it is involved in several ecological processes such as camouflage for prey-predator interactions or resistance to environmental variations. Among insects, aphids are known to produce different body-color morphs depending on their biotic and abiotic environments and their bacterial endosymbionts. The English-grain aphid (EGA) Sitobion avenae produces both red and green morphs in cereal fields. Using both field studies on the Canadian prairies (Saskatchewan) and laboratory experiments, we aimed to study the mechanisms that trigger plasticity in body coloration to better understand the ecological role of body coloration and color-change evolved by animals, including aphids. We first analyzed green and red morph EGA distribution on wheat ears in different fields and showed that red aphids were mostly located at the top of the ear and green aphids at the bottom. Then, using DNA sequencing, we showed that red and green morphs did not strongly differ in their bacterial endosymbiont composition and abundances. Finally, using a climate-chamber setup in the laboratory, we highlighted that EGA body-coloration is under light-intensity control and that it is possible to turn aphids from green back to red within a few days, and from red back to green within a couple of weeks (low-to-high and high-to-low light intensities, respectively). Light-intensity-controlled color-change likely results in adaptive plasticity in response to shifts in environmental conditions that can occur over the lifespan of an aphid, and is fully reversible, even at the adult stage. [ABSTRACT FROM AUTHOR]