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Nano-selenium (Se) has attracted growing attention due to its high bioavailability, low toxicity and its possible applications in the prevention of oxidative damage in animal tissues. Recent research works have conveyed that the use of nano-seleniumas food additive could have positive effects on the nutrition of aquatic animals.In this study, the intestinal bacterial communities associated with low and high concentrations of nano-selenium in the diet of Chinese tongue sole were characterized, through 16S rRNA V3–V4 sequencing.Samples were derived from fish fed with diet containing different nano-selenium level, 0 mg/kg for the control group, 1.6 mg/kg for low dose group, and 2.4 mg/kg for high dose group The intestinal microbial community structure showed a low overall diversity, among which the vibro genus occupied the most important position with more than 90% relative abundance in all three group. Significant differences in specie diversity occurred between the nano-selenium treated (both low dose [IL] and high dose [LH]) groups and the control group(IC). Acinetobacter, Arthrobacter, and Streptophytes were the top three enriched genera after the treatment with nano-selenium compared to IC. Meantime, the weight gain rate of the LH group was 9% higher than control. The results revealed the effect of nano-selenium on microbial community structure of gut and growth performance of C.semilaevis, Future research exploring the interaction mechanism between micronutrients and the microbial communities would increase our understanding of the fish nutrition.

Predicting species abundance is one of the most fundamental pursuits of ecology. Combining the information encoded in functional traits and metacommunities provides a new perspective to predict the abundance of species in communities. We applied a community assembly via trait selection model to predict quadrat-scale species abundances using functional trait variation on ontogenetic stages and metacommunity information for over 490 plant species in a subtropical forest and a lowland tropical forest in Yunnan, China. The relative importance of trait-based selection, mass effects, and stochasticity in shaping local species abundances is evaluated using different null models. We found both mass effects and trait selection contribute to local abundance patterns. Trait selection was detectable at all studied spatial scales (0.04–1 ha), with its strength stronger at larger scales and in the subtropical forest. In contrast, the importance of stochasticity decreased with spatial scale. A significant mass effect of the metacommunity was observed at small spatial scales. Our results indicate that tree community assembly is primarily driven by ontogenetic traits and metacommunity effects. Our findings also demonstrate that including ontogenetic trait variation into predictive frameworks allows ecologists to infer ecological mechanisms operating in community assembly at the individual level.

Native plant communities are commonly invaded by invasive plants to different degrees. However, the relative contribution of the invasive plant abundance vs. phylogenetic evenness to the responses of wetland communities to different degrees of invasion is still unclear. In addition, whether such contribution varies with environmental conditions such as flooding is also unclear. To address these questions, we chose Alternanthera philoxeroides as the invasive plant, and set up four invasive degrees by changing the community species composition under both flooding and non-flooding conditions. The relative abundance of A. philoxeroides and phylogenetic evenness changed simultaneously with the change in the community invasion degree. The invasion degree significantly affected the individual biomass of A. philoxeroides and some native species. Variation partitioning showed that the relative abundance of A. philoxeroides contributed more to variation in community indicators than phylogenetic evenness, regardless of flooding. Spearman rank correlation test showed that the relative abundance of A. philoxeroides was negatively correlated with the individual biomass of A. philoxeroides and some native species, while the phylogenetic evenness was positively correlated with only a few native species. And their correlation strength and significance were all affected by specific species and flooded environment. In conclusion, our results suggest that the relative abundance of A. philoxeroides can more effectively explain the wetland community response to different invasion degrees than phylogenetic evenness, regardless of flooding.

The effects of different chemical oxygen demand (COD) concentrations on the anammox granular sludge with Bamboo Charcoal (BC) addition were evaluated in UASB reactor. The results showed that the average total nitrogen (TN) removal efficiency was reduced from 85.9% to 81.4% when COD concentration was increased from 50 to 150 mg/L. However, the TN removal efficiency of BC addition reactors was dramatically 3.1%–6.4% higher than that without BC under different COD concentrations. The average diameter of granular sludge was 0.13 mm higher than that without BC. The settling velocity was increased by elevated COD concentration, while the EPS and VSS/SS were increased with BC addition. The high-throughput Miseq sequencing analyses revealed that the bacterial diversity and richness were decreased under COD addition, and the Planctomycetes related to anammox bacteria were Candidatus Brocadia and Candidatus Kuenenia. The Metagenomic sequencing indicated that the abundance of denitrification related functional genes all increased with elevated COD, while the abundance of anammox related functional genes of decreased. The functional genes related to anammox was hydrazine synthase encoding genes (hzsA, hzsB and hzsB). The average relative abundance of hzs genes in the reactor with BC addition was higher than the control at COD concentrations of 50 mg/L and 150 mg/L. The functional genes of denitrification mediated by BC were higher than those without BC throughout the operation phase. It is interesting to note that BC addition greatly enriched the related functional genes of denitrification and anammox.

Aims This study aims to investigate the effect of hydroxy-selenomethionine supplementation on the in vitro rumen fermentation characteristics and microorganisms of Holstein cows. Methods and Results Five fermentation substrates, including control (without selenium supplementation, CON), sodium selenite supplementation (0.3 mg kg−1 DM, SS03), and hydroxy-selenomethionine supplementation (0.3, 0.6 and 0.9 mg kg−1 DM, SM03, SM06 and SM09, respectively) were incubated with rumen fluid in vitro. The results showed that in vitro dry matter disappearance and gas production at 48 h was significantly higher in SM06 than SM03, SS03 and CON; propionate and total volatile fatty acid (VFA) production was higher in SM06 than CON. Moreover, higher species richness of rumen fluid was found in SM06 than others. Higher relative abundance of Prevotella and Prevotellaceae-UCG-003 and lower relative abundance of Ruminococcus-1 were detected in SM06 than CON. Besides, higher relative abundance of Ruminococcaceae_UCG-005 was found in CON than other treatments. Conclusions It is observed that 0.6 mg kg−1 DM hydroxy-selenomethionine supplementation could increase cumulative gas production, propionate, and total VFAs production by altering the relative abundance of Prevotella, Prevotellaceae-UCG-003, Ruminococcaceae_UCG-005 and Ruminococcus-1, so that it can be used as a rumen fermentation regulator in Holstein cows. Significance and Impact of the Study This study provides an optimal addition ratio of hydroxy-selenomethionine on rumen fermentation and bacterial composition via an in vitro test.

The behavior of fish around bait is poorly understood despite it being important for the fish catching process and estimating relative abundance. We used a fine-scale acoustic positioning system to quantify the movements of 26 red snapper (Lutjanus campechanus) around 120 bait deployments in 2019 at a natural reef site (∼37-m deep) in North Carolina, USA. There were 39 instances of tagged red snapper approaching bait during four baiting days, some of which approached due to apparent sensory cues (28%), while most approached incidentally (72%). Tagged red snapper approached bait from initial distances of 1 to 1147 m (median = 27 m; mean = 86 m), and took 0–77 min (mean = 22 min) to approach. Fish were more likely to approach bait if they were located close to, and down-current of, the bait at deployment. Our estimated effective fishing area of 2290 m2 (within which >50% of red snapper responded to bait) could be used along with video counts and other information to estimate densities of red snapper.

Biodiversity is under enormous pressure from multiple threats including climate change, land use change, habitat alterations and hunting pressure. One way to ease this pressure on biodiversity and to mitigate the effects of above-mentioned threats, is to establish protected areas. Importance of protected increases many folds in regions that are considered as biodiversity poor regions i.e. deserts. Protected areas have long been a major pillar of biodiversity conservation strategies; the Houbara Protected Area (HPA) is one of the 13 terrestrial protected areas in Abu Dhabi Emirate officially declared in 2017. However, no information regarding the status of biodiversity in the HPA has been communicated to the research fraternity. During the present study, surveys were conducted to fill this gap. The survey area was divided in to 50 grids of 5 × 5 km2 and monitoring surveys were undertaken from January to December 2016. A total of 14 bi-monthly to monthly surveys were conducted within HPA and 196 species of different taxonomical groups were recorded. A year-long survey yielded highly diversified fauna and flora from 19 different habitat types (H) 1.32, (E) 2.28, Shannon Diversity Index). We looked at the influence of habitat breadth and temperature on the species richness and abundance, results shows that in desert setup heterogeneity of habitat is not an important factor in maintaining the biodiversity as total number of individuals as well as species were similar in the grids that have different number of habitat types (df = 34.3, t = -0.472, P = 0.640). However, we did find a positive impact of mean monthly temperature on species richness (df = 154, t = 2.53, P = 0.012). Our study highlights the importance of temperature in driving species abundance and richness in protected area. Abundance and species richness are similar in protected areas indicating that protection is allowing species to explore the heterogenous habitats. Overall, we can conclude that protection is beneficial for species.

The human gut microbiome harbors substantial ecological diversity at the species level as well as at the strain level within species. In healthy hosts, species abundance fluctuations in the microbiome are thought to be stable, and these fluctuations can be described by macroecological laws. However, it is less clear how strain abundances change over time. An open question is whether individual strains behave like species themselves, exhibiting stability and following the macroecological relationships known to hold at the species level, or whether strains have different dynamics, perhaps due to the relatively close phylogenetic relatedness of cocolonizing lineages. Here, we analyze the daily dynamics of intraspecific genetic variation in the gut microbiomes of four healthy, densely longitudinally sampled hosts. First, we find that the overall genetic diversity of a large majority of species is stationary over time despite short-term fluctuations. Next, we show that fluctuations in abundances in approximately 80% of strains analyzed can be predicted with a stochastic logistic model (SLM), an ecological model of a population experiencing environmental fluctuations around a fixed carrying capacity, which has previously been shown to capture statistical properties of species abundance fluctuations. The success of this model indicates that strain abundances typically fluctuate around a fixed carrying capacity, suggesting that most strains are dynamically stable. Finally, we find that the strain abundances follow several empirical macroecological laws known to hold at the species level. Together, our results suggest that macroecological properties of the human gut microbiome, including its stability, emerge at the level of strains. IMPORTANCE To date, there has been an intense focus on the ecological dynamics of the human gut microbiome at the species level. However, there is considerable genetic diversity within species at the strain level, and these intraspecific differences can have important phenotypic effects on the host, impacting the ability to digest certain foods and metabolize drugs. Thus, to fully understand how the gut microbiome operates in times of health and sickness, its ecological dynamics may need to be quantified at the level of strains. Here, we show that a large majority of strains maintain stable abundances for periods of months to years, exhibiting fluctuations in abundance that can be well described by macroecological laws known to hold at the species level, while a smaller percentage of strains undergo rapid, directional changes in abundance. Overall, our work indicates that strains are an important unit of ecological organization in the human gut microbiome.

Bacteria can form dense communities called biofilms, where cells are embedded in a self-produced extracellular matrix. Exploiting competitive interactions between strains within the biofilm context can have potential applications in biological, medical, and industrial systems. By combining mathematical modelling with experimental assays, we reveal that spatial structure and competitive dynamics within biofilms are significantly affected by the location and density of the founder cells used to inoculate the biofilm. Using a species-independent theoretical framework describing colony biofilm formation, we show that the observed spatial structure and relative strain biomass in a mature biofilm comprising two isogenic strains can be mapped directly to the geographical distributions of founder cells. Moreover, we define a predictor of competitive outcome that accurately forecasts relative abundance of strains based solely on the founder cells’ potential for radial expansion. Consequently, we reveal that variability of competitive outcome in biofilms inoculated at low founder density is a natural consequence of the random positioning of founding cells in the inoculum. Extension of our study to non-isogenic strains that interact through local antagonisms, shows that even for strains with different competition strengths, a race for space remains the dominant mode of competition in low founder density biofilms. Our results, verified by experimental assays using Bacillus subtilis, highlight the importance of spatial dynamics on competitive interactions within biofilms and hence to related applications.

This study explored the microbial community and the energy requirement of an anaerobic packed bed reactor (APBR) treating a low-strength synthetic wastewater (200 mg COD/L). The APBR was run with different hydraulic retention times (HRTs) and temperatures. Results show that the COD removal decreased from 89 to 46% when the HRTs and the temperature were both gradually reduced to 1 h and 20oC. Meanwhile, the methane yield decreased from 0.386 to 0.232 g COD/g TCODconsumed with the decreasing temperature from 35 to 20oC at 1-h HRT. This low methane production was associated with a low relative abundance of 0.575 to 0.628% for the archaea group in genus level. Genus Methanosaeta with 0.307 to 0.388% relative abundance represented 53 to 62% of the archaea group whereas facultative Trichococcus with 7.3 to 11.3% relative abundance was dominant in the microbial consortia. Candidatus Moduliflexus found was the second largest microbial population with 4.2 to 6.1% relative abundance. This facultative environment was observed in the APBR, resulting in 18 to 37% COD unbalanced. The energy appraisement resolved that the total electrical energy required for the APBR was consistent at 4.192×10-3 kWh/m3 at 20 to 35°C to yield the net energy ratio of 5.97 to 15.29. The facultative-like APBR treated the low strength wastewater efficiently while the energy input was balanced by its self-produced methane energy.

Presence of methanotrophs in diverse environmental habitats helps to reduce emissions of greenhouse gas like methane. Isolation and culture of undiscovered wealth of methanotrophic organisms can help in exploitation of these organisms in value added products. The present study focuses on the enrichment of methanotroph dominated mixed microbial community by use of three stage strategy of revival, proliferation, and segregation. During the enrichment process amplicon sequencing of 16 s rRNA V3-V4 region showed relative abundance of mixed culture comprising single methanotrophic species of Methylocystis genus (88.92%) along with only three other species. Methylocystis dominant mixed culture (MMI-11) was observed to produce polyhydroxyalkanoates (PHA). During studies to identify favourable culture conditions, nitrate was found to be preferred nitrogen source for growth and PHA production. Cell growth ability to produce PHA was also evaluated at 14 L fermentor by supplying gas using continuous bubbling and through pressurization in the headspace. The mixed methanotrophic culture was found to accumulate maximum of 22.20% polyhydroxybutyrate (PHB) under nitrate limited condition. The molecular weight of PHB was found to be 2.221 × 105 g mol-1 with polydispersity of 1.82.

Long-chain alkenones (LCAs) produced by phylogenetically classified Groups 1 and 3 Isochrysidales are increasingly used for paleotemperature and/or paleosalinity reconstructions in oligohaline lakes and marine environments. However, there are considerable difficulties in the paleoenvironmental interpretation of LCAs from Group 2 Isochrysidales thriving in saline lakes. The biggest challenge lies in our poor understanding of the complexity and ecological niches of individual Group 2 subclades in saline lakes. Here, we perform comprehensive analysis of haptophyte-specific 18S rRNA sequences and distributions of LCAs, and long-chain alkenoates (LCEs) in surface sediments and suspended particulate matter (SPM) from 37 saline lakes in northern China. These lakes span a large salinity gradient from 0.5 to 308‰. Combined with published genomic data of Group 2 Isochrysidales, our phylogenetic analysis reveals three Group 2 subclades occupying distinct ecological niches: one ice-related bloomer Group 2i and two warm-season bloomers Groups 2w1 and 2w2. Group 2i, the earliest seasonal bloomer, frequently co-occurs with Group 2w1 in sediments from saline lakes with relatively low to intermediate salinity waters, whereas Group 2w2 blooms in hypersaline waters. Based on existing data, C39:4 methyl alkenone is a chemotaxonomic biomarker for Group 2i. %C37:4 (relative abundance of C37:4 to the total C37 alkenones) values in the three Group subclades follow the order: Group 2i > Group 2w2 > Group 2w1. The %C37:4 in sediment cores of saline lakes does not directly record past salinity changes, but instead reflects variable contributions in production by these three subclades. This could indirectly and partially reflect overall salinity changes in some lakes dominated by Groups 2i and 2w1, but can be more complicated in lakes dominated by other assemblages. For our sites, we also demonstrate that direct use of C37 alkenone unsaturation indices ( U 37 K , U 37 K ' , and U 37 K ' ' ) for paleotemperature reconstructions in saline lakes is generally not feasible, except for cases where alkenone-producing Isochrysidales are dominated by one single species/subclade and seasonal production effects can be circumvented. We propose two possible alternative proxies for paleotemperature reconstructions in saline lakes: 1) unsaturation ratios of C41 and C42 alkenones, as these compounds are predominantly produced by a limited number of Group 2 species, such as Isochrysis nuda ( Liao et al., 2020 ); 2) C38Et/C36OEt ratio (ratio of C38 ethyl alkenones and C36 ethyl alkenoates), which appears to have similar temperature sensitivity for Groups 2w1 and 2w2, in lakes with no Group 2i inputs. Our study provides new insights into the phylogenetic classifications of Group 2 Isochrysidales and their ecological/environmental niches, which are fundamental for more quantitative and rigorous applications of LCAs and LCEs in saline lakes as paleosalinity and paleotemperature proxies.

Forest is the most significant habitat for birds by supporting around 75% of all bird species while only 45% of all bird species have adapted to humans modified habitats. The research was conducted in the Montane Forest Research Station, Jos, Plateau State, in other to determine the abundance, diversity and effect of habitat types on bird’s species diversity. Fifteen transects of 200m were laid in the three habitat types (riparian forest, farmland and residential area) using stratified random sampling method. The data collected were analysed using R console. Shannon Weiner diversity index was used to analyse species diversity while generalized linear model was used to determine the effect of the habitat variables on bird species diversity. The result showed a total number of 1466 individual birds belonging to 17 families and 60 bird species were sighted. The abundance of birds was highest in riparian forest (2252), farmland (1732) and Residential area (1094) with no significance difference (p=0.177). Species richness was higher in the riparian forest (57), farmland (49), and the residential area (44). It also revealed that bird diversity index was highly significant. Riparian forest had the highest diversity (4.77), and the species were more evenly distributed (0.6) as compared to the other habitat types. The higher the number of trees and canopy cover the higher the diversity of species as was observed in the riparian forest where forest species that weren’t seen in the other habitats were found. The farmland and residential areas also hold a considerable number of some generalist bird species due to some patches of vegetation found in the habitat. Therefore, conservation efforts should be directed towards keeping vegetation intact in human dominated areas, as it serves as repository for bird species which are ecologically important. Hence, planting trees (economic, fruit and ornamental) should be encouraged.

Objective To investigate the microbiome characteristics of peri-implant mucositis (PM) and peri-implantitis (PI), and to analyze the correlation between disease severity and submucosal microbial dysbiosis. Materials and methods A cross-sectional study design was conducted. Submucosal biofilm samples from 27 PM sites and 37 PI sites from 64 patients were collected and analysed using 16S rRNA gene sequencing (Illumina). Differences in microbiological profiles between PM and PI were evaluated using α-diversity, β-diversity and linear discriminant analysis effect size (LEfSe) analysis. The relative abundances of the taxa at the phylum and genus levels were compared using the Wilcoxon rank test and logistic regression. The microbial dysbiosis index (MDI) was calculated and its relationship with clinical measurements (probing depth, bleeding on probing, and marginal bone loss, among others) was analysed using Pearson's correlation coefficient. Results The overall microbiome distribution in the PM and PI sites was similar according to α- and β-diversity. Twenty-three taxa at the genus level and two taxa at the phylum level showed significant differences in relative abundance between the two clinical classifications. Five taxa at the genus level were screened out for the MDI calculation after logistic regression. No clinical measurements but marginal bone loss showed a significant positive correlation with microbial dysbiosis. Conclusion The microbiome richness, diversity and distribution were similar in PM and PI sites, including both common periodontal bacteria and novel species. In addition, an increase in marginal bone loss was significantly associated with submucosal microbial dysbiosis.

Background To determine the presence and abundance of an aquatic species in large waterbodies, especially when populations are at low densities, is highly challenging for conservation biologists. Environmental DNA (eDNA) has the potential to offer a noninvasive and cost-effective method to complement traditional population monitoring, however, eDNA has not been extensively applied to study large migratory species. Chinese sturgeon (Acipenser sinensis), is the largest anadromous migratory fish in the Yangtze River, China, and in recent years its population has dramatically declined and spawning has failed, bringing this species to the brink of extinction. In this study, we aim to test the detectability of eDNA methods to determine the presence and relative abundance of reproductive stock of the species and whether eDNA can be used as a tool to reflect behavioral patterns. Chinese sturgeon eDNA was collected from four sites along the spawning ground across an eight month period, to investigate the temporal and spatial distribution using droplet digital PCR (ddPCR). Results We designed a pair of specific primers for Chinese sturgeon and demonstrated the high sensitivity of ddPCR to detect and quantify the Chinese sturgeon eDNA concentration with the limit of detection 0.17 copies/μl, with Chinese sturgeon eDNA been intermittently detected at all sampling sites. There was a consistent temporal pattern among four of the sampling sites that could reflect the movement characteristics of the Chinese sturgeon in the spawning ground, but without a spatial pattern. The eDNA concentration declined by approximately 2–3 × between December 2018 and December 2019. Conclusions The results prove the efficacy of eDNA for monitoring reproductive stock of the Chinese sturgeon and the e decreased eDNA concentration reflect that Chinese sturgeon may survive with an extremely small number of reproductive stock in the Yangtze River. Accordingly, we suggest future conservation measures should focus on both habitat restoration and matured fish restocking to ensure successful spawning. Overall, this study provides encouraging support for the application of eDNA methods to monitor endangered aquatic species.

Limestone quarries are known to be places where the diversity of xerothermophilic organisms is promoting diversity and in some, there are water bodies that potentially support the presence of hydrobionts. These include dragonflies (Insecta: Odonata), which, as amphibiotic insects, use both aquatic and terrestrial habitats. The purpose of this paper was to determine whether there was a high diversity of odonatofauna in an old limestone quarry with well-developed aquatic habitats, located in an urban environment in the Central-European city of Krakow (S Poland). For this purpose, dragonflies in the quarry were monitored regularly, focusing on the reproductive status and relative abundance of each species. In 2017–2018, 37 species belonging to seven families of Odonata were recorded in the quarry, which is 50% of the Poland’s odonatofauna. Of these, 33 species were considered indigenous to the quarry. Among them, 30% were moderately urbanophobic or urbanophobic taxa. Habitat specialists made up 39% of the species. Some rare and declining species, i.e. Leucorrhinia pectoralis and L. rubicunda, were abundant at this site. The study shows that a well-preserved secondary habitat, located in the centre of a city and not subject to urban management, can support a high diversity of odonates. Such limestone quarries in highly transformed urban environments can be valuable sites for this indicator group of organisms and should be identified, evaluated and conserved.

Effective control of aquatic invasive species requires knowledge of the population throughout the infested area. Lake-wide assessments of invasive sea lampreys (Petromyzon marinus) are used to assess their status in the Laurentian Great Lakes, informing fisheries managers and decision makers in the sea lamprey control program. Initially these assessments focused on an estimate of absolute abundance, but later switched to an estimate of relative abundance as an index. In this paper, we describe the recently developed index of sea lamprey abundance and the reasons for its use. Rather than trying to estimate spawning run sizes of all Great Lakes tributaries, the index instead estimates run sizes of a small subset of index streams. Streams chosen for the index had large spawning runs and a history of trapping operations that consistently yielded mark-recapture estimates. This change enabled the sea lamprey control program to abandon a previously used regression model that predicted run size on streams with no sea lamprey traps. Further research is needed to determine how strongly correlated the index is with actual patterns in the lake-wide population of adult sea lampreys.

Lake trout (Salvelinus namaycush) is the presumed preferred host of the invasive sea lamprey (Petromyzon marinus) in the Great Lakes, but little is understood about this preference outside of laboratory experiments. By preference we mean sea lamprey attacks on hosts are disproportionate to host relative abundance. The purpose of this study was to quantify host preference of sea lampreys in the field for the first time. We focused our analysis on Lake Ontario, where the two dominant host species for sea lampreys are lake trout and Chinook salmon (Oncorhynchus tshawytscha). Sea lampreys exhibited a strong preference for lake trout when host abundance was ≥ 32% lake trout, but sea lamprey preference switched to Chinook salmon when host abundance was ≤ 13% lake trout. Model results were equivocal with respect to determining whether the primary predictor of sea lamprey preference was relative or absolute abundance of lake trout. Other evidence, particularly the different spatial distributions of the two hosts, suggests that sea lamprey preference for lake trout is based on a higher encounter probability, driven by absolute abundance of lake trout. This study confirms a widely held concern that observed sea lamprey-induced marking rates on lake trout, used to assess the status of sea lamprey control in the Great Lakes, can be influenced by the abundance of alternative hosts. As an alternative host for sea lamprey parasitism, Chinook salmon may contribute to the persistence of lake trout in Lake Ontario.

Tigriopus kingsejongensis, a copepod species reported from the King Sejong Station, Antarctica, serves as a valuable food resource in ecosystems. We cultured T. kingsejongensis at three different temperatures (2 °C, 8 °C, and 15 °C) in a laboratory to observe the changes in its fecal pellet microbiome depending on the cultivation temperatures and developmental stages. We observed that the fecal pellet microbiome of the copepod changed with temperature: a lower microbial diversity, higher abundance of the aquatic bacterium Vibrio, and lower abundance of the psychrophilic bacterium Colwellia were noted at higher temperatures. In addition, the fecal pellet microbiome of the copepod changed according to the developmental stage: a lower microbial diversity was noted in egg-attached copepods than in nauplii at 8 °C. We further analyzed three shotgun metagenomes from the fecal pellet samples of T. kingsejongensis at different temperatures and obtained 44 metagenome-assembled genomes (MAGs). We noted that MAGs of V. splendidus D contained glycosyl hydrolases (GHs) encoding chitinases and virulence factors at a higher relative abundance at 15 °C than at lower temperatures. These results indicate that increasing temperature affects the fecal pellet microbiome and the development of copepods. The findings are helpful to understand the changes in cold-adapted copepods and the effect of temperature on their growth.

Due to its topographic and climatic diversity, the state of Querétaro possesses high levels of amphibian and reptile richness, abundance, and endemism. However, this information must be updated constantly as regions with previously little to no information are further explored, using sampling methods that allow efficient recording of biological diversity. The objective of this study was to compare herpetofaunistic diversity among three different vegetation types (oak–forest, grassland, and associated secondary vegetation) using two sampling methods (pitfall/funnel traps and transects). We registered thirteen species: five amphibians, and eight reptiles. We found differences in species dominancy with amphibians showing higher values of relative abundance in oak forest and grassland for both sampling methods. Transects showed a higher effective number of species for q0, q1, and q2. The oak forest and secondary vegetation possess comparable similarity percentages and did not show significant differences (p = 0.54). We observed significant differences between the grassland and secondary vegetation (p = 0.02). We found high distinctness levels (> 70%) between sampling techniques. The present study shows the importance of protected natural areas as shelters for threatened groups such as amphibians and reptiles, and highlights the importance of using complementary sampling methods.

The results of monitoring studies carried out to identify the features of the current distribution of vegetation and productivity of sandy pasture ecosystems in the south of the European territory of Russia are presented. The objects of research were natural pasture phytocenoses on the territory of the Tsimlyansk sand massif. The methods of ecological and geobotanical surveys were used in the work. Plant samples were collected at key sites located in different wet areas using the 5-fold slope method. To identify dominant and subdominant species of natural phytocenoses, the Drude species abundance assessment scale was used. It was found that the pasture ecosystems of the Tsimlyansk sand massif are characterized by the presence of 58 dominant and subdominant species from 22 families, which occupy a certain position in the herbaceous and shrub communities, depending on the moisture content of the territory. The territory of complete humidification is characterized by the presence of 7 dominants and subdominants from 7 families. In the territory of excessive moisture, 9 species from 7 families dominate in phytocenoses. On the territory of sufficient and variable moisture, 26 species from 8 families predominate in the communities. The territories of moderate humidification are distinguished by the presence in the associations of 22 dominant species from 9 families. The territory of complex moistening, which is insufficient and severely insufficient under sand hills and moderate in the groves, is characterized by the presence of 9 dominant and subdominant species from 6 families in the communities. In 2018-2020 it was revealed that the annual phytomass of the grass and grass communities of the Tsimlyansk sand massif increases from spring to summer (from 91-117 to 204-267 g/m2) and decreases from summer to autumn (from 204-267 to 156-190 g / m2). The average annual productivity of natural phytocenoses is 156-190 g / m2.

Tabanids (Diptera: Tabanidae) are large haematophagous flies that cause both direct (by biting nuisance) and indirect (primarily by mechanical transmission of diseases) damage to host species. Research studies on this family have received little attention in some parts of Europe. Our aims were to characterise the species richness, abundance, and peak of activity of tabanid fly species in a region of Northern Spain. Home-made canopy traps, sweep nets, and Malaise traps were employed for the collection of tabanids across four cattle farms, two equestrian centres, and two golf courses during a 3-month period in the summer of 2020. A total of 300 specimens of 27 tabanid species belonging to eight genera were identified. The most prevalent species were Haematopota pluvialis (23.3%), Tabanus eggeri (20.0%), and Tabanus bromius (8.0%). The former species was recorded biting humans and therefore should be considered of relevance to public health. Tabanids were more diverse and abundant in scrubland and grazing pastures [relative abundance (RA) = > 10%; species richness (S) = 8–12; Shannon-Index (H´) = 1.5 − 2.1] compared to crop landscapes (RA =

Untimely, forceful, and unexpected death is inevitable and common worldwide. Evidence for causes of death may be obtained through the knowledge of insects’ successional pattern and postmortem interval on dead carcasses. Two rabbits (Lepus cuniculus) weighing 2.5 kg each were used as the experimental animals. The rabbits were sacrificed by poisoning and stabbing, postmortem evaluation was achieved by taking record of the insect’s successional pattern. The insects’ successional pattern revealed the following insects’ species in order in which they arrived on the carcasses: Musca domestica, Lucilia sericata, Chrysomya albiceps, Dermestes maculatus, and Armadillidium vulgare (usual sp). The family Formicidae were represented by two unidentified species. M. domestica arrived first on the stabbed carcass while L. sericata on poisoned carcass. A total of 105±50 insects were collected throughout the study period, with stabbed rabbit contributing 61±10 and poisoned 44±60 insects’ species. Variation in the number of forensically important insects’ species encountered in the study site did not show any significant difference (p>0.05) in relation to each decomposition stage. There was however a significant difference (p

Despite important implications for human health, distribution, abundance and behaviour of most medically-relevant snakes remain poorly understood. Such data deficiencies hamper efforts to characterise the causal pathways of snakebite envenoming and to prioritise management options in the areas at greatest risk. We estimated the spatial patterns of abundance of seven medically-relevant snake species from Sri Lanka, a snakebite hotspot, and combined them with indices of species’ relative abundance, aggressiveness and envenoming severity obtained from an expert opinion survey to test whether these fundamental ecological traits could explain spatial patterns of snakebite and envenoming incidence. The spatial intensity of snake occurrence records in relation to independent environmental factors (fundamental niches and land cover) was analysed with point process models. Then, with the estimated patterns of abundance, we tested which species’ abundances added together, with and without weightings for aggressiveness, envenoming severity and relative abundance, best correlate with per-capita geographic incidence patterns of snakebite and envenoming. We found that weighting abundance patterns by species’ traits increased correlation with incidence. The best performing combination had three species weighted by aggressiveness and abundance, with a correlation of r = 0.47 (P < 0.01) with snakebite incidence. An envenoming severity and relative abundance-weighted combination of two species was the most strongly associated with envenoming incidence (r = 0.46, P = 0). Synthesis and applications. We show that snakebite risk is explained by abundance, aggressiveness and envenoming severity of the snake species most frequently involved in envenoming cases. Incorporating causality via ecological information of key snake species is critical for snakebite risk mapping, help to tailor preventive measures for dominant snake species and deploy the necessary antivenom therapies.

Bacterial communities form the basis of biogeochemical processes and determine plant growth and health. Mosses harbour diverse bacterial communities that are involved in nitrogen fixation and carbon cycling. Global climate change is causing changes in aboveground plant biomass and shifting species composition in the Arctic, but little is known about the response of moss microbiomes in these environments. Here, we studied the total and potentially active bacterial communities associated with Racomitrium lanuginosum in response to a 20-yr in situ warming in an Icelandic heathland. We evaluated the effect of warming and warming-induced shrub expansion on the moss bacterial community composition and diversity, and nifH gene abundance. Warming changed both the total and the potentially active bacterial community structure, while litter abundance only affected the total bacterial community structure. The abundance of nifH genes was negatively affected by litter abundance. We also found shifts in the potentially nitrogen-fixing community, with Nostoc decreasing and noncyanobacterial diazotrophs increasing in relative abundance. Our data suggest that the moss microbial community and potentially nitrogen fixing taxa will be sensitive to future warming, partly via changes in litter and shrub abundance.

The grass carp is one of the most important herbivore consumers in aquatic ecosystems and plays key roles in controlling macrophyte abundance. To assess the trophic role of grass carp and their potential grazing pressure on macrophytes in their native range, we quantified their relative abundance (RA), diet composition and trophic niches in two major tributaries and the central delta of the Pearl River using a fish capture survey, high-throughput analysis of the 18S rDNA sequences of their gut contents, and stable isotope analysis. The grass carp RA variation among the sampling regions was explained most by river discharge range. The RA was the highest in the West River with high discharge range, and the lowest in the central delta with low discharge range. The grass carp fed primarily on Streptophyta (relative read abundance: 0.40 ± 0.33) and facultatively on Arthropoda, Rotifera, Ascomycota, and Chlorophyta. The Streptophyta proportion increased from the tributaries to the central delta. Such variation contributed most to the dietary difference among regions. Grass carp belonged to the second trophic level. The position and size of isotopic niche of grass carp differed among regions, and their niche breadth decreased from the tributaries to the central delta, as indicated by the corrected standard ellipse areas (SEAs) and the Bayesian SEAs. The regional differences in hydrological regime and grass carp RA probably affected the macrophyte distribution. The availability of macrophytes likely further contributed to the regional difference in the Streptophyta proportion in grass carp diet.

The unprecedented size of the deepwater horizon oil spill and scope of the subsequent response elicited intense and sustained interest in microbial responses to oiling, especially in salt marshes, which have featured prominently in debates about best practices to prevent and remediate oiling of vulnerable ecosystems. A number of studies have examined salt marsh soil microbial communities following the spill, but most have primarily concentrated on prokaryotes. The extent to which oiling elicited shifts in fungal diversity and community composition remains unclear. Here we present spatial and temporal comparisons of salt marsh soil fungal communities at two southern Louisiana salt marshes with contrasting oiling histories. We profiled fungal communities in 2013 alongside corresponding measurements of polycyclic aromatic hydrocarbons to assess whether and how responses to oiling are distinguishable from natural heterogeneity. Analyses based on high-resolution unbiased spatial sampling demonstrated that fungal communities did not align with shoreline classification of oiling less than three years after initial oiling, despite observable differences in oil residues and secondary oiling. Notably, extensive sampling allowed delineation of benchmark sampling thresholds and illustrated the value of using ranked differentials of relative abundance to characterize soil fungal communities. Our findings highlight the need for combining high-resolution sampling with judgment-based and systematic sampling approaches to accurately capture responses of salt marsh soil fungal community to oiling.

The geographical distribution of plant resources is of great significance for studying the origin, distribution, and evolution of species. Climate and geographical factors help shape the distribution of plant species. Dendrobium is a commonly used traditional medicine and a precious economic crop in China. Owing to the over-exploitation and increasing medicinal demand of Dendrobium species plants, systematic investigation of the geographical distribution of the plants and analysis of their potential distribution under climate change are important for protecting Dendrobium plants. We adopted DIVA-GIS to analyze the georeferenced records of 76 species of the Dendrobium species collected from 2166 herbarium records. We analyzed the eco-geographical distribution and species richness of the genus Dendrobium to simulate the distribution of current and future scenarios using MaxEnt. The results revealed the distribution of Dendrobium in 30 provinces of China, with species abundance in Yunnan, Guangxi, Guangdong, and Hainan. Our model identified the following bioclimatic variables: precipitation in the driest months and the warmest seasons, isothermality, and range of annual temperature. Among them, annual precipitation is the most crucial bioclimatic variable affecting the distribution of 16 selected Dendrobium species. The change of climate in the future will lead to an increase in habitat suitability for some Dendrobium species as follows: D. officinal 2.12%, D. hancockii by 6.00%, D. hercoglossum by 8.25%, D. devonianum by 7.71%, D. henryi by 9.40%, and D. hainanense by 13.70%. By contrast, habitat suitability will dramatically decrease for other Dendrobium species: D. chrysotoxum by 0.89%, D. chrysanthum by 12.68%, D. fimbriatum by 5.07%, D. aduncum by 11.44%, D. densiflorum by 18.47%, D. aphyllum by 8.05%, D. loddigesii by 16.45%, D. nobile by 5.41%, D. falconeri by 8.73%, and D. moniliforme by 10.61%. The reduction of these species will be detrimental to the medicinal and economic value of the genus Dendrobium. Therefore, targeted development and reasonable management strategies should be adopted to conserve these valuable resources.

No-till (NT) and fertilization are common land management practices in agricultural production systems to increase soil quality and crop yield. No-till can be reversed to tillage (termed tillage reversal, TR, in this paper) due to changes in management objectives. The impact of NT, TR, and TR plus nitrogen (N) fertilization (TRN) treatments on the composition and structure of bacterial communities in a Gray Luvisol was studied in west-central Alberta, Canada. The structure of bacterial communities was not affected by the TR treatment (compared with NT). The TRN treatment increased the relative abundance of some bacterial taxa groups, e.g., Gemmatimonadetes, Thermoleophilia and Solibacteres, that have chemolithotrophic nitrifying functions as compared with the TR treatment. The decreased relative abundance of some bacterial taxa groups, such as Alphaproteobacteria, Deltaproteobacteria, Spartobacteria, and Planctomycetia that have denitrifying functions, would change the soil’s denitrification function in the TRN as compared to the TR treatment. There were more dominant bacterial taxa groups, and the bacterial community had greater inter-annual variations in the TRN than in the NT and TR treatments. Moreover, the function of bacterial communities was affected by the TRN as compared to the NT and TR treatments, based on the predicted metagenomes. We conclude that when TR was applied to the soil with long-term N fertilization, which eliminates N limitation, altered soil bacterial community structure and function over TR applied to the studied Gray Luvisol without long-term N fertilization. Findings from our study have important implications for improving land management practices through tillage and N fertilization to enhance the soil’s function and quality in agroecosystems.

This study investigated the effects of representative co-substrate (corncob particles) and additive (brick granules) alone on antibiotic resistome of swine manure during composting and subsequent compost application. For relative abundances, four antibiotic resistance gene (ARG) types encoding resistance to aminoglycoside, multidrug, florfenicol-chloramphenicol-amphenicol-fluoroquinolone-quinolone, and sulfonamide increased remarkably during composting, whereas all the ARG types decreased after compost application. Interestingly, much more ARG subtypes (50.1% in total) were reduced in corncob addition treatment. Meanwhile, the addition of corncob particles lowered the relative abundance and diversity of ARGs more significantly. Microbial community exhibited conspicuous changes across the manure, compost, and soil samples where the dominant genera were completely different. Procrustes test proved the co-occurrence and driving effect of microbial community on resistome variation, especially in corncob addition treatment during composting. Network analysis demonstrated that the dissipation of the dominant genera such as Ruminofilibacter, Luteimonas, and Pseudidiomarina in the composts after application contributed greatly to the reduction in ARG relative abundance. Besides, the low abundance of mobile genetic elements (MGEs) in soil also accounted for the attenuation of ARGs to some extent. Our findings clearly proved that co-composting materials can further affect the attenuation of antibiotic resistome in soil application, which can help in understanding the spread and control of ARGs during agricultural process.

Using samples collected in Shahe Reservoir in the upper North Canal in China, this research analyzes the structure of a microorganism group in sediment and the gene expression levels of two typical pathogenic bacteria (Escherichia coli and Enterococcus), and their relationship with environmental factors including total nitrogen (TN) and total phosphorus (TP). The study of samples collected from the surface (0–20 cm) and sediment cores shows that the absolute gene expression level of E. coli in in horizontal distribution in the sediment is higher than the relative gene expression level in the downstream of the reservoir and contaminated area. In vertical distribution, the absolute gene expression level of the two pathogenic bacteria in the sediment tends to decrease with increasing depth, although the relative gene expression level has its highest value at 10–30 cm depth. The relative gene expression level of the two pathogenic bacteria is much greater in the sediment of Shahe Reservoir with the structure of horizontal groups including Clortridium sensu stricto, unclassified Anaeroineaceae, and Povalibacter, while Anaeroineaceae is much more abundant in the group structure of the vertical distribution. Pearson correlation analysis suggests positive correlation in horizontal distribution for E. coli and TN and TP (P Enterococcus and TP (P

As one of the most abundant predators of insects in terrestrial ecosystems, spiders have long received much attention from agricultural scientists and ecologists. Do spiders have a certain controlling effect on the main insect pests of concern in farmland ecosystems? Answering this question requires us to fully understand the prey spectrum of spiders. Next‐generation sequencing (NGS) has been successfully employed to analyze spider prey spectra. However, the high sequencing costs make it difficult to analyze the prey spectrum of various spider species with large samples in a given farmland ecosystem. We performed a comparative analysis of the prey spectra of Ovia alboannulata (Araneae, Lycosidae) using NGS with individual and mixed DNA samples to demonstrate which treatment was better for determining the spider prey spectra in the field. We collected spider individuals from tea plantations, and two treatments were then carried out: (1) The DNA was extracted from the spiders individually and then sequenced separately (DESISS) and (2) the DNA was extracted from the spiders individually and then mixed and sequenced (DESIMS). The results showed that the number of prey families obtained by the DESISS treatment was approximately twice that obtained by the DESIMS treatment. Therefore, the DESIMS treatment greatly underestimated the prey composition of the spiders, although its sequencing costs were obviously lower. However, the relative abundance of prey sequences detected in the two treatments was slightly different only at the family level. Therefore, we concluded that if our purpose were to obtain the most accurate prey spectrum of the spiders, the DESISS treatment would be the best choice. However, if our purpose were to obtain only the relative abundance of prey sequences of the spiders, the DESIMS treatment would also be an option. The present study provides an important reference for choosing applicable methods to analyze the prey spectra and food web compositions of animal in ecosystems., Individual DNA sample sequencing obtains the accurate prey spectrum of spiders. Mixed DNA sample sequencing underestimates the prey spectrum of spiders. Individual and mixed DNA sample sequencing obtains almost the same relative abundance of prey sequences of spiders.

Information from camera traps is used for inferences on species presence, richness, abundance, demography, and activity. Camera trap placement design is likely to influence these parameter estimates. Herein we simultaneously generate and compare estimates obtained from camera traps (a) placed to optimize large carnivore captures and (b) random placement, to infer accuracy and biases for parameter estimates. Both setups recorded 25 species when same number of trail and random cameras (n = 31) were compared. However, species accumulation rate was faster with trail cameras. Relative abundance indices (RAI) from random cameras surrogated abundance estimated from capture-mark-recapture and distance sampling, while RAI were biased higher for carnivores from trail cameras. Group size of wild-ungulates obtained from both camera setups were comparable. Random cameras detected nocturnal activities of wild ungulates in contrast to mostly diurnal activities observed from trail cameras. Our results show that trail and random camera setup give similar estimates of species richness and group size, but differ for estimates of relative abundance and activity patterns. Therefore, inferences made from each of these camera trap designs on the above parameters need to be viewed within this context.

Negative effects of long‐term overgrazing have been seriously, grasslands temporal stability is an important ecological concern we need to research. Here, we performed a 12‐year‐long (2007–2018) two‐factor controlled experiment on Kobresia humilis meadow on the Tibetan Plateau. The manipulations included three clipping levels (no clipping, NC; moderate clipping, MC; heavy clipping, HC) and two fertilization levels (no fertilization, NF; fertilization, F). Our results revealed that the two clipping manipulations significantly increased the temporal stability of alpine meadow communities, whose significant increase was more pronounced under the MC than HC treatment. Species asynchrony had a significant positive correlation with species abundance along with compound community gradient. Moreover, asynchrony effects, portfolio effects, and facilitation interactions were all present in the communities under the six types of experimental treatment combinations. Additionally, a selection effect was detected in the compound communities, demonstrating characteristics that are common to different mechanisms. There were no significant differences in the effects of these mechanisms on community temporal stability between the NC–NF and MC–NF interactive communities. The portfolio effects predominated when clipping intensity was moderate under both fertilization and nonfertilization conditions. By contrast, in the compound communities, the selection effect predominated. In summary, we conclude that in meadow communities that undergo clipping and fertilization disturbances, facilitation interactions and weak interactions make a greater contribution toward maintaining their temporal stability., Under six experimental conditions of clipping and fertilization levels, we found that fertilization, as well as heavy and especially moderate clipping intensity, significantly increased the temporal stability of K. humilis. Asynchrony effects, portfolio effects, and facilitation interactions were all present under the six experimental treatment conditions in this study. Clipping mainly increased community temporal stability via the asynchrony effect, whereas this increase under fertilization treatment was mainly owing to facilitation and weak interactions.

Estimates of abundance and their changes through time are key elements of marine mammal conservation and management. Absolute marine mammal abundance in a region of the open ocean is often difficult to attain. However, methods of estimating their abundance based on passive acoustic recordings are becoming increasingly employed. This study shows that passive acoustic monitoring of North Atlantic minke whales with a single hydrophone provides sufficient information to estimate relative population abundance. An automated detector was developed for minke whale pulse trains and an approach for converting its output into a relative abundance index is proposed by accounting for detectability as well as false positives and negatives. To demonstrate this technique, a 2 y dataset from the seven sites of the Atlantic Deepwater Ecosystem Observatory Network project on the U.S. east coast was analyzed. Resulting relative abundance indices confirm pulse train-calling minke whale presence in the deep waters of the outer continental shelf. The minkes are present December through April annually with the highest abundance near the site offshore of Savannah, Georgia.

The present study focused on the seasonal investigation of hydro-geochemical characteristics of groundwater samples collected from the vicinity of three tributaries of the Beas River, Punjab, India. Total 45 samples were analyzed during the pre- and post-monsoon season for physico-chemical parameters and heavy metals along with health risk assessment. Results revealed that the majority of samples were below the permissible limits set by the BIS and WHO. The relative abundance of major cations was Ca2+ > Mg2+ > Na+ > K+ and Ca2+ > Na+ > Mg2+ > K+, while that of the major anions was HCO3− > SO42− > Cl− > CO32− in the pre- and post-monsoon season, respectively. Groundwater was alkaline and hard in nature at most of the sites. Bicarbonate content exceeded the desirable limit having an average concentration of 337.26 mg/L and 391.48 mg/L, respectively, during the pre- and post-monsoon season. Tukey’s multiple comparison test was applied for finding significant differences among samples at p 3 type. US salinity (USSL) diagram indicated that during the pre-monsoon, 48.9% samples were C2S1 type and remaining 51.1% were C3S1 type while during the post-monsoon all samples were C3S1 type. It indicates that groundwater of the study area is at risk of salinity hazards in future and is not to be ignored. Such monitoring studies are recommended to design future safety plans to combat soil and human health risks.

Urbanization processes are increasing globally. Anthropogenic alterations in the environment have profound effects on biodiversity. Decreased biodiversity due to biotic homogenization processes as a consequence of urbanization often result in increased levels of mosquito vector species and vector-borne pathogen transmission. Understanding how anthropogenic alterations in the environment will affect the abundance, richness, and composition of vector mosquito species is crucial for the implementation of effective and targeted mosquito control strategies. We hypothesized that anthropogenic alterations in the environment are responsible for increasing the abundance of mosquito species that are adapted to urban environments such as Aedesaegypti and Culexquinquefasciatus. Therefore, our objective was to survey mosquito relative abundance, richness, and community composition in Miami-Dade County, Florida, in areas with different levels of urbanization. We selected 24 areas, 16 remote areas comprised of natural and rural areas, and 8 urban areas comprised of residential and touristic areas in Miami-Dade County, Florida. Mosquitoes were collected weekly in each area for 24 h for 5 consecutive weeks from August to October 2020 using BG-Sentinel traps baited with dry ice. A total of 36,645 mosquitoes were collected, from which 34,048 were collected in the remote areas and 2,597 in the urban areas. Our results show a clear and well-defined pattern of abundance, richness, and community composition according to anthropogenic modifications in land use and land cover. The more urbanized a given area the fewer species were found and those were primary vectors of arboviruses, Ae.aegypti and Cx.quinquefasciatus.

Blackflies are amongst the most abundant and diverse group of aquatic insects globally, being rarely absent from rivers, their distributions are largely driven by current velocity, conductivity and total dissolved solids (TDS). While research on blackflies has mainly focused on medical, veterinary and economic aspects, ecological studies in the Afrotropical Region are relatively scarce. This study aimed to determine the response of blackfly species to environmental drivers in the north-eastern tropical regions of South Africa. Generalized Linear mixed models and the Permutational Multivariate Analysis of Variance were fitted to model blackfly richness and abundance structure. The Threshold Indicator Taxa Analysis (TITAN) was used to analyze species-specific change along environmental gradients. A total of 1343 larvae, representing seven blackfly species in four sub-genera, were collected from 22 sites over a twelve-month period. Water temperature and flow velocity were the most important drivers of species richness. Conductivity and land cover had the strongest effect on community composition across species and sites. Species responded synchronously along flow velocity and water temperature gradients at 1.6 m.s−1 and between 20–22 °C, respectively. Simulium (Metomphalus) hargreavesi was identified at an indicator species for flow velocity, while three were indicator species for water temperature change. We demonstrated that the richness and relative abundance of blackflies are driven by different variables across the Luvuvhu catchment. The new information obtained from this study provides an insight on the importance of protecting and managing the natural environment in a high biodiversity and endemism area.

Abstract Oil palm (OP) plantations are gradually replacing tropical rainforest in Malaysia, one of the largest palm oil producers globally. Conversion of lands to OP plantations has been associated with compositional shifts of the microbial community, with consequences on the greenhouse gas (GHG) emissions. While the impact of the change in land use has recently been investigated for microorganisms involved in N2O emission, the response of the aerobic methanotrophs to OP agriculture remains to be determined. Here, we monitored the bacterial community composition, focusing on the aerobic methanotrophs, in OP agricultural soils since 2012, 2006, and 1993, as well as in a tropical rainforest, in 2019 and 2020. High-affinity methane uptake was confirmed, showing significantly lower rates in the OP plantations than in the tropical rainforest, but values increased with continuous OP agriculture. The bacterial, including the methanotrophic community composition, was modified with ongoing OP agriculture. The methanotrophic community composition was predominantly composed of unclassified methanotrophs, with the canonical (Methylocystis) and putative methanotrophs thought to catalyze high-affinity methane oxidation present at higher relative abundance in the oldest OP plantation. Results suggest that the methanotrophic community was relatively more stable within each site, exhibiting less temporal variations than the total bacterial community. Uncharacteristically, a 16S rRNA gene-based co-occurrence network analysis revealed a more complex and connected community in the OP agricultural soil, which may influence the resilience of the bacterial community to disturbances. Overall, we provide a first insight into the ecology and role of the aerobic methanotrophs as a methane sink in OP agricultural soils.

Morphological trait-matching and species abundance are thought to be the main factors affecting the frequency and strength of mutualistic interactions. However, the relative importance of trait-matching and species abundance in shaping species interactions across environmental gradients remains poorly understood, especially for plant-insect mutualisms involving generalist species. Here, we characterised variation in species and trait composition and the relative importance of trait-matching and species abundance in shaping plant-Hymenoptera and plant-Diptera mutualisms in four meadows across an elevational gradient (2,725-3,910 m) in Yulong Snow Mountain, Southwest China. We also evaluated the effects of morphological traits of flower visitors and plant composition on their foraging specialisation (d' and normalised degree). There was a high degree of dissimilarity in the composition of Hymenoptera and Diptera visitors and their visited plants between communities. This variation was mainly driven by the spatial replacement of species. Both for plant-Hymenoptera and plant-Diptera networks, trait-matching between nectar tube depth and proboscis length was a stronger predictor of the interactions between temporally co-occurring plants and flower visitors than species abundance. Fourth-corner analyses revealed statistically significant trait-matching between nectar tube depth and proboscis length in plant-Hymenoptera networks at all sites, suggesting that Hymenoptera consistently foraged on plant species with nectar tube depths matching their proboscis lengths. By contrast, significant trait-matching in plant-Diptera networks was only observed at the two lower elevation sites. The species-level specialisation d' of flower visitors increased significantly as the proboscis length and the difference in nectar tube depth between the plant community and the plants visited by flower visitors increased. Our results highlight that the importance of trait-matching in shaping pairwise interactions and niche partitioning depends on the specific features (e.g. species composition and trait availability) of the plant-pollinator system. For specialised plant-Hymenoptera systems, trait-matching is an important determinant of species interactions, whereas for generalist plant-Diptera systems, trait-matching is relatively unimportant., H.W. was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB31000000), the Joint Fund of the National Natural Science Foundation of China-Yunnan Province (U1502261), the Yunling Scholarship of Yunnan Provincial Government (YLXL20170001) and National Natural Science Foundation of China (32071670). Y.-H.Z. was supported by the National Natural Science Foundation of China (31700361) and the Chinese Academy of Sciences ‘Light of West China’ Program. A.L. was supported by a Ramóny Cajal (RYC-2015-19034) contract from the Spanish Ministry of Science, Innovation and Universities, the Spanish State Research Agency, European Social Funds (ESF invests in your future), and the University of the Balearic Islands, and by the project CGL2017-89254-R financed by the Spanish Ministry of Economy and Competitiveness, Feder Funds, and the Spanish Research Agency (Call 2017).

1. Competition for shared resources is commonly assumed to restrict population-level niche width of coexisting species. However, the identity and abundance of coexisting species, the prevailing environmental conditions, and the individual body size may shape the effects of interspecific interactions on species’ niche width. 2. Here we study the effects of interspecific and intraspecific interactions, lake area and altitude, and fish body size on the trophic niche width and resource use of a generalist predator, the littoral-dwelling large, sparsely rakered morph of European whitefish (Coregonus lavaretus; hereafter LSR whitefish). We use stable isotope, diet and survey fishing data from 14 subarctic lakes along an environmental gradient in northern Norway. 3. The isotopic niche width of LSR whitefish showed a humped-shaped relationship with increasing relative abundance of sympatric competitors, suggesting widest population niche at intermediate intensity of interspecific interactions. The isotopic niche width of LSR whitefish tended to decrease with increasing altitude, suggesting reduced niche in colder, less productive lakes. 4. LSR whitefish typically shifted to a higher trophic position and increased reliance on littoral food resources with increasing body size, although between-lake differences in ontogenetic niche shifts were evident. In most lakes, LSR whitefish relied less on littoral food resources than coexisting fishes and the niche overlap between sympatric competitors was most evident among relatively large individuals (>250 mm). Individual niche variation was highest among >200 mm long LSR whitefish, which likely have escaped the predation window of sympatric predators. 5. We demonstrate that intermediate intensity of interspecific interactions may broaden species’ niche width, whereas strong competition for limited resources and high predation risk may suppress niche width in less productive environments. Acknowledging potential humped-shaped relationships between population niche width and interspecific interactions can help us understand species’ responses to environmental disturbance (e.g. climate change and species invasions) as well as the driving forces of niche specialization.

Macroalgal holobiont studies involve understanding interactions between the host, its microbiota, and the environment. We analyzed the effect of bacteria-kelp interactions on phenotypic responses of two genetically distinct populations of giant kelp, Macrocystis pyrifera (north and south), exposed to different nitrogen (N) concentrations. In co-culture experiments with different N concentration treatments, we evaluated kelp growth responses and changes in three specific molecular markers associated with the N cycle, both in epiphytic bacteria (relative abundance of nrfA-gene: cytochrome c nitrite reductase) and macroalgae (expression of NR-gene: nitrate reductase; GluSyn-gene: glutamate synthase). Both kelp populations responded differently to N limitation, with M. pyrifera-south sporophytes having a lower specific growth rate (SGR) under N-limiting conditions than the northern population; M. pyrifera-north sporophytes showed no significant differences in SGR when exposed to low-N and high-N concentrations. This corresponded to a higher GluSyn-gene expression in the M. pyrifera-north sporophytes and the co-occurrence of specific nrfA bacterial taxa. These bacteria may increase ammonium availability under low-N concentrations, allowing M. pyrifera-north to optimize nutrient assimilation by increasing the expression of GluSyn. We conclude that bacteria-kelp interactions are important in enhancing kelp growth rates under low N availability, although this effect may be regulated by the genetic background of kelp populations.