Assessment Of Community Composition Research Articles

Local environmental conditions structured discrete fish assemblages in Arctic lagoons

AbstractRapid changes in sea ice extent and changes in freshwater inputs from land are rapidly changing the nature of Arctic estuarine ecosystems. In the Beaufort Sea, these nearshore habitats are known for their high productivity and mix of marine resident and diadromous fishes that have great subsistence value for Indigenous communities. There is, however, a lack of information on the spatial variation among Arctic nearshore fish communities as related to environmental drivers. In summers of 2017–2019, we sampled fishes in four estuarine ecosystems to assess community composition and relate fish abundance to temperature, salinity, and wind conditions. We found fish communities were heterogeneous over larger spatial extents with rivers forming fresh estuarine plumes that supported diadromous species (e.g., broad whitefish Coregonus nasus), while lagoons with reduced freshwater input and higher salinities were associated with marine species (e.g., saffron cod Eleginus gracilis). West–East directional winds accounted for up to 66% of the community variation, indicating importance of the wind-driven balance between fresh and marine water masses. Salinity and temperature accounted for up to 54% and 37% of the variation among lagoon communities, respectively. Recent sea ice declines provide more opportunity for wind to influence oceanographic conditions and biological communities. Current subsistence practices, future commercial fishing opportunities, and on-going oil and gas activities benefit from a better understanding of current fish community distributions. This work provides important data on fish spatial distributions and community composition, providing a basis for fish community response to changing climatic conditions and anthropogenic use.

A comparison of two gene regions for assessing community composition of eukaryotic marine microalgae from coastal ecosystems

Two gene regions commonly used to characterise the diversity of eukaryotic communities using metabarcoding are the 18S ribosomal DNA V4 and V9 gene regions. We assessed the effectiveness of these two regions for characterising diverisity of coastal eukaryotic microalgae communities (EMCs) from tropical and temperate sites. We binned amplicon sequence variants (ASVs) into the high level taxonomic groups: dinoflagellates, pennate diatoms, radial centric diatoms, polar centric diatoms, chlorophytes, haptophytes and ‘other microalgae’. When V4 and V9 generated ASV abundances were compared, the V9 region generated a higher number of raw reads, captured more diversity from all high level taxonomic groups and was more closely aligned with the community composition determined using light microscopy. The V4 region did resolve more ASVs to a deeper taxonomic resolution within the dinoflagellates, but did not effectively resolve other major taxonomic divisions. When characterising these communities via metabarcoding, the use of multiple gene regions is recommended, but the V9 gene region can be used in isolation to provide high-level community biodiversity to reflect relative abundances within groups. This approach reduces the cost of sequencing multiple gene regions whilst still providing important baseline ecosystem function information.

Spatial distribution and diversity of the heterotrophic flagellates in the Cosmonaut Sea, Antarctic

As predators of bacteria and viruses and as food sources for microzooplankton, heterotrophic flagellates (HFs) play an important role in the marine micro-food web. Based on the global climate change’s impact on marine ecosystems, particularly sea ice melting, we analyzed the community composition and diversity of heterotrophic flagellates, focusing on the Antarctic Cosmonaut Sea. During the 36th China Antarctic research expedition (2019-2020), we collected seawater samples, subsequently analyzing HFs through IlluminaMiSeq2000 sequencing to assess community composition and diversity. Notable variations in HFs abundance were observed between the western and eastern sectors of the Cosmonaut Sea, with a distinct concentration at a 100-meter water depth. Different zones exhibited diverse indicators and dominants taxa influenced by local ocean currents. Both the northern Antarctic Peninsula and the western Cosmonaut Sea, where the Weddell Eddy and Antarctic Land Slope Current intersect, showcased marine stramenopiles as dominant HFs species. Our findings offer insights into dominant taxa, spatial distribution patterns among heterotrophic flagellates, correlations between taxa distribution and environmental factors, and the exploration of potential indicator taxa.

Rates of species turnover across elevation vary with vertical stratum in rainforest ant assemblages

Climatic variation at local scales can influence both exposure and sensitivity of organisms and thereby scale up to influence population persistence and community composition across broader geographic extents. Tropical forest canopies are more climatically dynamic than the understorey. Consequently, the niche space of forest canopies has higher overlap in thermal conditions along elevation gradients, which imposes less of a climatic barrier to arboreal species than their ground‐dwelling counterparts. We use ant communities of the Australian Wet Tropics to test the prediction that ground communities should have higher rates of species turnover over elevation compared to arboreal communities. We sampled ground and arboreal ants along elevation gradients at a bioregional scale that includes four mountain sub‐regions. We assessed community composition at three spatial resolutions (regional, elevation, vertical) and then calculated beta diversity (species turnover) over elevation for ground and arboreal communities using null modelling procedures to compare different sized species pools. Vertical niche affinity was a strong contributor to overall biogeographic patterns; indicated by a strong interaction between vertical niche and elevation in beta diversity models. On average, the ground community exhibited a pronounced elevational distance–decay pattern while the arboreal community showed no pattern. Mean species turnover was 36% higher in ground than arboreal communities. Our findings suggest that the vertical niche has a pronounced effect on biogeographic patterns which has important implications for understanding the role of local scale climate conditions in shaping communities and for potential responses to future climate change.

Local environment drives rapid shifts in composition and phylogenetic clustering of seagrass microbiomes

Plant microbiomes depend on environmental conditions, stochasticity, host species, and genotype identity. Eelgrass (Zostera marina) is a unique system for plant–microbe interactions as a marine angiosperm growing in a physiologically-challenging environment with anoxic sediment, periodic exposure to air at low tide, and fluctuations in water clarity and flow. We tested the influence of host origin versus environment on eelgrass microbiome composition by transplanting 768 plants among four sites within Bodega Harbor, CA. Over three months following transplantation, we sampled microbial communities monthly on leaves and roots and sequenced the V4–V5 region of the 16S rRNA gene to assess community composition. The main driver of leaf and root microbiome composition was destination site; more modest effects of host origin site did not last longer than one month. Community phylogenetic analyses suggested that environmental filtering structures these communities, but the strength and nature of this filtering varies among sites and over time and roots and leaves show opposing gradients in clustering along a temperature gradient. We demonstrate that local environmental differences create rapid shifts in associated microbial community composition with potential functional implications for rapid host acclimation under shifting environmental conditions.

Habitat associations of imperilled fishes after conservation intervention in the Cape Fold Ecoregion, South Africa.

The aim of this study was to examine the habitat associations of a native cyprinid community of the recovering Rondegat River in the Cape Fold Ecoregion of South Africa as part of a long-term native fish abundance monitoring project. Relative abundance data were extracted from underwater video camera footage across the longitudinal gradient of the river in three sampling instances. Using multivariate methods the authors assessed community composition with respect to habitat, its overlap with a protected area and species-specific abiotic predictors of relative abundance. Distance from the uppermost site in the river was the most significant predictor of species abundance, indicating spatial segregation and varying overlap between species. The protected status of sites in the upper reaches, vegetated substrates and the size of individual sites were the most impactful on the relative abundance of the endangered fiery redfin Pseudobarbus phlegethon. The results of this study indicate that underwater video monitoring is an effective and low-cost approach that can inform conservation recommendations. Reducing agricultural runoff and sedimentation in the lower reaches may be useful further interventions to maintain key habitats of submerged vegetation.

The use of environmental DNA to monitor impacted coastal estuaries

Environmental DNA (eDNA) metabarcoding is increasingly being used to assess community composition in coastal ecosystems. In this study, we chose to examine temporal and spatial changes in the aquatic community of Manly Lagoon – one of the most heavily developed and polluted estuaries in eastern Australia. Based on metabarcoding of the 16S mitochondrial gene (for fish) and the 18S nuclear gene (for macroinvertebrates), we identified seasonal differences in fish and macroinvertebrate community composition as well as species richness, which correlated, in some cases, with the environmental parameters of sea surface temperature and freshwater input. Moreover, given the greater taxonomic resolution of fish versus macroinvertebrate assignments, we identified several known migratory fish species of management importance that contributed significantly to the overall patterns observed. Overall, our data support the use of eDNA metabarcoding to track fish assemblages shifting in response to environmental drivers in polluted estuaries with increased sampling and consultation with historical data.

Diversity of Arbuscular Mycorrhizal Fungi in Shola Forests of Kodaikanal, Southern India

Arbuscular mycorrhizal fungi establish symbiotic association with more than 80% of land plants and influence plant community composition and distribution. The mycorrhizal status of plant species in various ecosystems have been reported but failed to assess community composition of AM fungi in shola forests, therefore present study carried out to fulfill this research gap. A total of Seven AM fungal species could be isolated from Tiger and Kookal shoal and identified based on spore morphology. There is no significant difference among distribution of AM fungal spores in various seasons among sites. In both the sholas AM fungal spore numbers were high during the wet (September) season and the variation among spore numbers in different seasons among sites were insignificant. Arbuscular mycorrhizal spore of Funneliformis geosporum was the most frequent species and Funneliformis mosseae was the less frequent species. The frequency among various sites in both the Sholas was insignificant. The AM fungal species richness was high in Tiger Shola (six spores), whereas in Kookal Shola showed less species richness. The diversity indices like Shanon - Weaver index (H') and Simpson index (D) were calculated in all the sites and showed variation among shoals in four sites. Arbuscular mycorrhizal fungal community composition in this ecosystem have been elucidated to certain extent and used for conservation of shola species.

Predicting the Presence and Abundance of Bacterial Taxa in Environmental Communities through Flow Cytometric Fingerprinting.

ABSTRACTMicrobiome management research and applications rely on temporally resolved measurements of community composition. Current technologies to assess community composition make use of either cultivation or sequencing of genomic material, which can become time-consuming and/or laborious in case high-throughput measurements are required. Here, using data from a shrimp hatchery as an economically relevant case study, we combined 16S rRNA gene amplicon sequencing and flow cytometry data to develop a computational workflow that allows the prediction of taxon abundances based on flow cytometry measurements. The first stage of our pipeline consists of a classifier to predict the presence or absence of the taxon of interest, with yielded an average accuracy of 88.13% ± 4.78% across the top 50 operational taxonomic units (OTUs) of our data set. In the second stage, this classifier was combined with a regression model to predict the relative abundances of the taxon of interest, which yielded an average R2 of 0.35 ± 0.24 across the top 50 OTUs of our data set. Application of the models to flow cytometry time series data showed that the generated models can predict the temporal dynamics of a large fraction of the investigated taxa. Using cell sorting, we validated that the model correctly associates taxa to regions in the cytometric fingerprint, where they are detected using 16S rRNA gene amplicon sequencing. Finally, we applied the approach of our pipeline to two other data sets of microbial ecosystems. This pipeline represents an addition to the expanding toolbox for flow cytometry-based monitoring of bacterial communities and complements the current plating- and marker gene-based methods.IMPORTANCE Monitoring of microbial community composition is crucial for both microbiome management research and applications. Existing technologies, such as plating and amplicon sequencing, can become laborious and expensive when high-throughput measurements are required. In recent years, flow cytometry-based measurements of community diversity have been shown to correlate well with those derived from 16S rRNA gene amplicon sequencing in several aquatic ecosystems, suggesting that there is a link between the taxonomic community composition and phenotypic properties as derived through flow cytometry. Here, we further integrated 16S rRNA gene amplicon sequencing and flow cytometry survey data in order to construct models that enable the prediction of both the presence and the abundances of individual bacterial taxa in mixed communities using flow cytometric fingerprinting. The developed pipeline holds great potential to be integrated into routine monitoring schemes and early warning systems for biotechnological applications.

Environmental DNA reveals a multi‐taxa biogeographic break across the Arabian Sea and Sea of Oman

AbstractEnvironmental DNA (eDNA) is increasingly being used to assess community composition in marine ecosystems. Applying eDNA approaches across broad spatial scales now provide the potential to inform biogeographic analyses. However, to date, few studies have employed this technique to assess broad biogeographic patterns across multiple taxonomic groups. Here, we compare eDNA‐derived communities of bony fishes and invertebrates, including corals and sponges, from 15 locations spanning the entire length of the Omani coast. This survey includes a variety of habitats, including coral and rocky reefs, and covers three distinct marine ecoregions. Our data support a known biogeographic break in fish communities between the north and the south of Oman; however, the eDNA data highlight that this faunal break is mostly reflected in schooling baitfish species (e.g., sardines and anchovies), whereas reef‐associated fish communities appear more homogeneous along this coastline. Furthermore, our data provide indications that these biogeographic breaks also affect invertebrate communities, which includes corals, sponges, and broader eukaryotic groups. The observed community shifts were correlated with local environmental and anthropogenic differences characteristic of this coastline, particularly for the eDNA‐derived bony fish communities. Overall, this study provides compelling support that eDNA sequencing and associated analyses may serve as powerful tools to detect community differences across biogeographic breaks and ecoregions, particularly in places where there is significant variation in oceanographic conditions or anthropogenic impacts.

Short-term exposure to synthetic flaxseed lignan LGM2605 alters gut microbiota in mice.

LGM2605 is a synthetic version of the naturally occurring flaxseed lignan secoisolariciresinol diglucoside (SDG), with known anti‐inflammatory and antioxidant properties; however, its effects on gut microbial composition have not previously been evaluated. In the present study, we sought to determine how the 10‐day oral administration of LGM2605 alters the gut microbiota of mice. Eight‐week‐old female C57BL/6 mice were treated with either LGM2605 or saline, administered daily via oral gavage over a 10‐day treatment period. Upon termination of treatment, mouse cecums (n = 31) were collected, and cecal DNA was isolated. 16S rRNA genes were sequenced and analyzed in Mothur to identify changes in gut microbial composition induced by LGM2605 treatment (v. saline control). We then assessed community composition, performed indicator taxa analysis, and measured alpha and beta diversity. Overall, LGM2605 significantly altered the gut microbiota of mice; we reported alterations in 3 bacterial phyla and 22 genera as a result of treatment. The study here identifies for the first time significant alterations in the gut microbiota of mice following oral administration of LGM2605, in general shifting toward a more anti‐inflammatory composition. These findings lay the foundation for future investigations utilizing LGM2605 to control gut dysbiosis and, by extension, systemic inflammation.

Assessing species abundance and habitat preferences in a part of Nanda Devi Biosphere Reserve, western Himalaya

Present study is an attempt to understand the plant species abundance and habitat preferences using multivariate method in Nanda Devi Biosphere Reserve (NDBR), in western Himalaya. Soil, altitude, slope and differences are reported to be the most important parameters shaping the plant community in the mountains. Two representative areas i.e., Pindari–Sunderdhunga–Kafni site (PSK) of Kumaun region and Lata–Tolma–Phagti site (LTP) of Garhwal region with nineteen forest communities in buffer zone of NDBR have been investigated. All the forest communities were analyzed for assessing community composition and species density in relation to environmental variables. Out of 451 plant species recorded from the study sites, there was a dominance of herbs (70.5%) followed by shrubs (17.7%) and trees (11.8%). Maximum tree density in PSK and LTP sites was recorded in Betula utilis (535 ind ha−1) and mixed T. wallichiana–A. pindrow (1211 ind ha−1) communities respectively. The disturbed habitats in low to mid elevation areas are represented by low canopy cover and high seedling density in PSK site and high non-native species density in LTP site. Both the study sites are dominated by Betula utilis, Taxus wallichiana, Abies pindrow in high elevation areas securing high density of native and endemic species. Habitat preferences of different important species indicate their range of distribution and choice of association with other species.

The utility of environmental DNA from sediment and water samples for recovery of observed plant and animal species from four Mojave Desert springs

AbstractMojave Desert springs are fragile ecosystems, hosting endemic plants and animals, which are threatened by the increasing human demand for water and climate change. To develop management practices that will protect the groundwater‐dependent ecosystems at Mojave Desert springs, real‐time, low‐cost biodiversity monitoring, and assessments are required. Environmental DNA (eDNA) metabarcoding uses DNA shed from organisms (e.g., skin cells, feces, and pollen) that are present in water, air, soil, or sediment samples to assess community composition. This approach can increase the detection sensitivity for rare and elusive species, compared with expensive and time‐consuming conventional methods, which also require taxonomic expertise. This study tests the effectiveness of eDNA techniques in capturing the observed Mojave Desert spring biodiversity in the winter and spring of 2019 at four distinct, naturally occurring springs. We also test the utility of sample types (water vs. sediment) for capturing biodiversity. We found that each of the four Mojave Desert springs supports a unique biological community. Sediment samples contained the greatest biodiversity, but all sample types captured species observed in the field by humans or camera traps. We also found no statistical difference in species richness captured in winter and spring except for the Cytochrome Oxidase I marker, for which winter had greater biodiversity. This study supports the use of eDNA metabarcoding as an effective tool to mirror observation by human observers of ecological communities in desert springs. The study demonstrates the importance of appropriately timing eDNA field sampling, primer selection, and using field‐based surveys of wildlife and plants in addition to eDNA detection. This study also identified gaps in reference sequence databases for Mojave biodiversity and encourages collaboration of eDNA researchers with managers for effective conservation management plans.

Community Organization and Metagenomics of Bacterial Assemblages Across Local Scale pH Gradients in Northern Forest Soils.

Soil pH has shown to predict bacterial diversity, but mechanisms are still poorly understood. To investigate how bacteria distribute themselves as a function of soil pH, we assessed community composition, diversity, assembly, and gene abundance across local (ca. 1 km) scale gradients in soil pH from ~ 3.8 to 6.5 created by differences in soil parent material in three northern forests. Plant species were the same on all sites, with no evidence of agriculture in the past. Concentrations of extractable calcium, iron, and phosphorus also varied significantly across the pH gradients. Among taxa, Alphaproteobacteria and Acidobacteria were more common in soils with acidic pH values. Overall richness and diversity of OTUs peaked at intermediate pH values. Variations in OTU richness and diversity also had a quadratic fit with concentrations of extractable calcium and phosphorus. Community assembly was via homogeneous deterministic processes in soils with acidic pH values, whereas stochastic processes dominated in soils with near-neutral pH values. Although we expected selection via genes for acid tolerance response in acidic soils, genes for genetic information processing were more selective. Taxa in higher pH soils had differential abundance of transporter genes, suggesting adaptation to acquire metabolic substrates from soils. Soil bacterial communities in northern forest soils are incredibly diverse, and we still have much to learn about how soil pH and co-varying soil parameters directly drive gene selection in this critical component of ecosystem structure.

Changes in soil microbial communities in post mine ecological restoration: Implications for monitoring using high throughput DNA sequencing

The ecological restoration of ecosystem services and biodiversity is a key intervention used to reverse the impacts of anthropogenic activities such as mining. Assessment of the performance of restoration against completion criteria relies on biodiversity monitoring. However, monitoring usually overlooks soil microbial communities (SMC), despite increased awareness of their pivotal role in many ecological functions. Recent advances in cost, scalability and technology has led to DNA sequencing being considered as a cost-effective biological monitoring tool, particularly for otherwise difficult to survey groups such as microbes. However, such approaches for monitoring complex restoration sites such as post-mined landscapes have not yet been tested. Here we examine bacterial and fungal communities across chronosequences of mine site restoration at three locations in Western Australia to determine if there are consistent changes in SMC diversity, community composition and functional capacity. Although we detected directional changes in community composition indicative of microbial recovery, these were inconsistent between locations and microbial taxa (bacteria or fungi). Assessing functional diversity provided greater understanding of changes in site conditions and microbial recovery than could be determined through assessment of community composition alone. These results demonstrate that high-throughput amplicon sequencing of environmental DNA (eDNA) is an effective approach for monitoring the complex changes in SMC following restoration. Future monitoring of mine site restoration using eDNA should consider archiving samples to provide improved understanding of changes in communities over time. Expansion to include other biological groups (e.g. soil fauna) and substrates would also provide a more holistic understanding of biodiversity recovery.

Characterizing Chemoautotrophy and Heterotrophy in Marine Archaea and Bacteria With Single-Cell Multi-isotope NanoSIP.

Characterizing and quantifying in situ metabolisms remains both a central goal and challenge for environmental microbiology. Here, we used a single-cell, multi-isotope approach to investigate the anabolic activity of marine microorganisms, with an emphasis on natural populations of Thaumarchaeota. After incubating coastal Pacific Ocean water with 13C-bicarbonate and 15N-amino acids, we used nanoscale secondary ion mass spectrometry (nanoSIMS) to isotopically screen 1,501 individual cells, and 16S rRNA amplicon sequencing to assess community composition. We established isotopic enrichment thresholds for activity and metabolic classification, and with these determined the percentage of anabolically active cells, the distribution of activity across the whole community, and the metabolic lifestyle—chemoautotrophic or heterotrophic—of each cell. Most cells (>90%) were anabolically active during the incubation, and 4–17% were chemoautotrophic. When we inhibited bacteria with antibiotics, the fraction of chemoautotrophic cells detected via nanoSIMS increased, suggesting archaea dominated chemoautotrophy. With fluorescence in situ hybridization coupled to nanoSIMS (FISH-nanoSIMS), we confirmed that most Thaumarchaeota were living chemoautotrophically, while bacteria were not. FISH-nanoSIMS analysis of cells incubated with dual-labeled (13C,15N-) amino acids revealed that most Thaumarchaeota cells assimilated amino-acid-derived nitrogen but not carbon, while bacteria assimilated both. This indicates that some Thaumarchaeota do not assimilate intact amino acids, suggesting intra-phylum heterogeneity in organic carbon utilization, and potentially their use of amino acids for nitrification. Together, our results demonstrate the utility of multi-isotope nanoSIMS analysis for high-throughput metabolic screening, and shed light on the activity and metabolism of uncultured marine archaea and bacteria.

Comparison of Water Sampling between Environmental DNA Metabarcoding and Conventional Microscopic Identification: A Case Study in Gwangyang Bay, South Korea

Our study focuses on methodological comparison of plankton community composition in relation to ecological monitoring and assessment with data sampling. Recently, along with the advancement of monitoring techniques, metabarcoding has been widely used in the context of environmental DNA (eDNA). We examine the applicability of eDNA metabarcoding for effective monitoring and assessment of community composition, compared with conventional observation using microscopic identification in a coastal ecosystem, Gwangynag Bay in South Korea. Our analysis is based primarily on two surveys at a total of 15 study sites in early and late summer (June and September) of the year 2018. The results of our study demonstrate the similarity and dissimilarity of biological communities in composition, richness and diversity between eDNA metabarcoding and conventional microscopic identification. It is found that, overall, eDNA metabarcoding appears to provide a wider variety of species composition, while conventional microscopic identification depicts more distinct plankton communities in sites. Finally, we suggest that eDNA metabarcoding is a practically useful method and can be potentially considered as a valuable alternative for biological monitoring and diversity assessments.

Environmental DNA reveals landscape mosaic of wetland plant communities

Globally, floodplain wetlands have been dramatically impacted by changes in water regimes. A key indicator of change in wetland state is riparian and aquatic plant community composition. Plant communities are traditionally assessed by visual monitoring programs that assess community composition. However, results from these monitoring programs may be effected by antecedent conditions that govern plant growth, such as season. In this study we used environmental DNA (eDNA) to assess the spatial composition of wetland vegetation communities from six floodplain complexes along the Murray River, Australia and compared results to those derived from tradition plant surveys. Our analyses of eDNA were conducted targeting two gene regions: 18S RNA and trnL at the species and operational taxonomic unit (OTU) levels. Analysis revealed significant similarity between the spatial patterns derived from the eDNA data and those derived from the traditional monitoring data. Moreover, using the eDNA data, analysis of endemicity revealed the majority of OTUs and species occurred only at a single wetland or wetland complex. Few genera were shared between the traditional survey data set and the molecular data sets. But for those that were shared, detectability varied between gene fragments and among genera, ranging from 11 to 100% in the trnL data to 14.3–100% in the18S data. Our results show that landscape patterns in plant communities can be reliably derived from eDNA analysis, thus providing a cost-effective way of undertaking vegetation surveys.

Characterizing bumble bee (Bombus) communities in the United States and assessing a conservation monitoring method.

AimBumble bees (Hymenoptera: Apidae: Bombus) are economically and ecologically important pollinators in agroecosystems and wildland habitats. In the Nearctic region, there are approximately 41 species, of which the IUCN lists twelve species as vulnerable, endangered, or critically endangered. We conducted a standardized faunal survey to inform ongoing conservation efforts including petitions under review for the Endangered Species Act. Furthermore, we test the appropriateness of a methodology for accurately sampling bumble bee communities.LocationThe United States of America, including 31 sites in 15 states.MethodsWe surveyed 15 states in the summer of 2015 to assess community composition and relative species abundance at agricultural and seminatural sites throughout the United States. We collected approximately 100 bees, using aerial nets, from each of 31 sites and identified specimens to species, totaling 3,252 bees. We assessed our survey methodology to understand whether it accurately sampled the potential community of bumble bees at each site for utility in future monitoring efforts.ResultsAverage site species richness was 5.1 ± 2.05, and we detected 30 of the 41 species documented historically within the contiguous United States. Sampling a site beyond 100 bees rarely added additional species detections, whereas adding additional sampling sites within an ecoregion frequently increased the species richness for the ecoregion. Thirteen of the 30 species we detected each accounted for <1% of the total fauna, and two species accounted for 49.02% of all bees captured. Species richness and evenness increased with increasing latitude across communities.Main ConclusionsSpecies diversity and evenness in bumble bees increases in northern latitudes and increasing elevation in the United States; however, a few common species tend to dominate communities while many species occur only in low numbers. The results of this survey effort can inform current conservation evaluations and planning.

Establishment success and crop growth effects of an arbuscular mycorrhizal fungus inoculated into Swiss corn fields

A major strategy to increase the sustainability of agricultural systems consists of enhancing internal ecosystem processes that support crop production and reduce external resource inputs. However, specific approaches to achieve this goal still need to be identified. Here, we investigated whether inoculation with a high dose of a well-characterized strain of a plant symbiotic arbuscular mycorrhizal (AM) fungus into Swiss corn fields leads to successful establishment of the fungus in plant roots and can generate agronomic benefits for maize production.We used single-molecule real-time (SMRT) DNA sequencing to assess community composition of native AM fungi and identified environmental management and biological factors affecting AM fungal abundance, establishment success of the introduced fungus and effects of AMF inoculation on corn yield.While native AM fungal abundance was negatively related to soil P contents, we found significantly positive relationships between soil P contents and establishment success of the inoculated fungus. There was a significantly negative relationship between inoculum establishment and abundance of native AM fungi. Although molecular quantification using strain-specific qPCR indicated that the inoculated strain strongly increased in abundance in roots from most soils investigated, total AM fungal root colonization was only significantly increased in one soil, indicating successful competition of the inoculant for root niche space against native AM fungi. Positive effects on corn yield were only observed when inoculation increased root colonization and were negatively correlated to P fertilization levels.The results imply that phosphorus plays a major role in defining the abundance of native AM fungi and the composition of their communities and that these effects can determine establishment success of the inoculant. The results further indicate that positive effects on crop yield may only be expected when potentially achievable root colonization levels are not yet reached and AMF communities are not well developed.