Evolutionarily conserved core microbiota as an extended trait in nitrogen acquisition strategy of herbaceous species.

Microbiota have co-evolved with plants over millions of years and are intimately linked to plants, ranging from symbiosis to pathogenesis. However, our understanding of the existence of a shared core microbiota across phylogenetically diverse plants remains limited. A common garden field experiment was conducted to investigate the rhizosphere microbial communities of phylogenetically contrasting herbaceous families. Through a combination of metagenomic sequencing, analysis of plant economic traits, and soil biochemical properties, we aimed to elucidate the eco-evolutionary role of the core rhizosphere microbiota in light of plant economic strategies. We identified a conserved core microbiota consisting of 278 taxa that was closely associated with the phylogeny of the plants studied. This core microbiota actively participated in multiple nitrogen metabolic processes and showed a strong correlation with the functional potential of rhizosphere nitrogen cycling, thereby serving as an extended trait in the plant nitrogen acquisition. Furthermore, our examination of simulated species loss revealed the crucial role of the core microbiota in maintaining the rhizosphere community's network stability. Our study highlighted that the core microbiota, which exhibited a phylogenetically conserved association with plants, potentially represented an extension of the plant phenotype and played an important role in nitrogen acquisition. These findings held implications for the utilization of microbiota-mediated plant functions.

Whole-genome-based phylogenetic analyses provide new insights into the evolution of springtails (Hexapoda: Collembola).

Springtails (Collembola) stand as one of the most abundant, widespread, and ancient terrestrial arthropods on earth. However, their evolutionary history and deep phylogenetic relationships remain elusive. In this study, we employed phylogenomic approaches to elucidate the basal relationships among Collembola. We sampled whole-genome data representing all major collembolan lineages in proportion to their known diversity. To account for potential phylogenomic biases, we implemented various data extraction, locus sampling, and signal filtering strategies to generate matrices. Subsequently, we applied a diverse array of tree-searching and rate-modelling methods to reconstruct the phylogeny. Our analyses, utilizing different matrices and methods, converged on the same unrooted relationships among collembolan ingroups, supporting the current ordinal classification and challenging the monophyly of Arthropleona and Symphypleona s.l. However, discrepancies across analyses existed in the root of Collembola. Among various root positions, those based on more informative matrices and biologically realistic models, favoring a basal topology of Entomobryomorpha + (Symphypleona s.s. + (Neelipleona + Poduromorpha)), were supported by subsequent methodological assessment, topology tests, and rooting analyses. This optimal topology suggests multiple independent reduction of the pronotum in non-poduromorph orders and aligns with the plesiomorphic status of neuroendocrine organs and epicuticular structure of Entomobryomorpha. Fossil-calibrated dating analyses based on the optimal topology indicated late-Paleozoic to mid-Mesozoic origins of the crown Collembola and four orders. In addition, our results questioned the monophyly of Isotomidae and Neanuridae, underscoring the need for further attention to the systematics of these families. Overall, this study provides novel insights into the phylogenetic backbone of Collembola, which will inform future studies on the systematics, ecology, and evolution of this significant arthropod lineage.

Competition-Induced Macroscopic Superlubricity of Ionic Liquid Analogues by Hydroxyl Ligands Revealed by in Situ Raman.

High load-bearing capacity is one of the crucial indicators for liquid superlubricants to move toward practicality. However, some of the current emerging systems not only have low contact pressures but also are highly susceptible to further degradation due to water adsorption and even superlubricity failure. Herein, a novel choline chloride-based ionic liquid analogues (ILAs) of a superlubricant with triethanolamine (TEOA) as the H-bond donor is reported for the first time; it obtains an ultralow coefficient of friction (0.005) and high load-bearing capacity (360 MPa, more than 2 times that of similar systems) due to adsorption of a small amount of water (<5 wt %) from the air. In situ Raman combined with 1H NMR and FTIR techniques reveals that adsorbed water competes with the hydroxyl group of TEOA for coordination with Cl-, leading to the conversion of some strong H-bonds to weak H-bonds in ILAs; the localized strong H-bonds and weak H-bonds endow the ILAs with high load-bearing capacity and the formation of ultralow shear-resistance sliding interfaces, respectively, under the shear motion. This study proposes a strategy to modulate the interactions between liquid species using adsorbed water from air as a competing ligand, which provides new insights into the design of ILA-based macroscopic liquid superlubricants with a high load-bearing capacity.

Phylogenomics of Elongate-Bodied Springtails Reveals Independent Transitions from Aboveground to Belowground Habitats in Deep Time.

Soil has become a major hotspot of biodiversity studies, yet the pattern and timing of the evolution of soil organisms are poorly known because of the scarcity of paleontological data. To overcome this limitation, we conducted a genome-based macroevolutionary study of an ancient, diversified, and widespread lineage of soil fauna, the elongate-bodied springtails (class Collembola, order Entomobryomorpha). To build the first robust backbone phylogeny of this previously refractory group, we sampled representatives of major higher taxa (6 out of 8 families, 11 out of 16 subfamilies) of the order with an emphasis on the most problematic superfamily Tomoceroidea, applied whole-genome sequencing methods, and compared the performance of different combinations of data sets (universal single-copy orthologs [USCO] vs. ultraconserved elements]) and modeling schemes. The fossil-calibrated timetree was used to reconstruct the evolution of body size, sensory organs, and pigmentation to establish a time frame of the ecomorphological divergences. The resultant trees based on different analyses were congruent in most nodes. Several discordant nodes were carefully evaluated by considering method fitness, morphological information, and topology test. The evaluation favored the well-resolved topology from analyses using USCO amino acid matrices and complex site-heterogeneous models (CAT$+$GTR and LG$+$PMSF (C60)). The preferred topology supports the monophyletic superfamily Tomoceroidea as an early-diverging lineage and a sister relationship between Entomobryoidea and Isotomoidea. The family Tomoceridae was recovered as monophyletic, whereas Oncopoduridae was recovered as paraphyletic, with Harlomillsia as a sister to Tomoceridae and hence deserving a separate family status as Harlomillsiidae Yu and Zhang fam. n. Ancestral Entomobryomorpha were reconstructed as surface-living, supporting independent origins of soil-living groups across the Paleozoic-Mesozoic, and highlighting the ancient evolutionary interaction between aboveground and belowground fauna. [Collembola; phylogenomics; soil-living adaptation; whole-genome sequencing.].

Management effects on soil nematode abundance differ among functional groups and land-use types at a global scale.

Anthropogenic land use is threatening global biodiversity. As one of the most abundant animals on Earth, nematodes occupy several key positions in belowground food webs and contribute to many ecosystem functions and services. However, the effects of land use on nematode abundance and its determinants remain poorly understood at a global scale. To characterize nematodes' responses to land use across trophic groups, we used a dataset of 6,825 soil samples globally to assess how nematode abundance varies among regional land-use types (i.e. primary vegetation, secondary vegetation, pasture, cropland and urban) and local land-use intensities (i.e. human-managed or not). We also quantified the interactive effects of land use and environmental predictors (i.e. mean annual temperature, annual precipitation, soil organic carbon, soil pH, global vegetation biomass and global vegetation productivity) on nematode abundance. We found that total nematode abundance and the abundance of bacterivores, fungivores, herbivores, omnivores and predators generally increased or were not affected under management across land-use types. Specifically, the most numerically abundant bacterivores were higher in managed than in unmanaged secondary vegetation habitats and urban areas, and herbivores were more abundant in managed than in unmanaged primary and secondary vegetation habitats. Furthermore, the numbers of significant environmental predictors of nematode abundance were reduced and the magnitude and the direction of the predictors were changed under management. We also found that nematode abundance was more variable and less determined by environmental factors in urban than in other land-use types. These findings challenge the view that human land use decreases animal abundance across trophic groups, but highlight that land use is altering the trophic composition of soil nematodes and its relationships with the environment at the global scale.

Molecular phylogeny and trait evolution in an ancient terrestrial arthropod lineage: Systematic revision and implications for ecological divergence (Collembola, Tomocerinae).

Phylogenetic assessments of functional traits are important for mechanistically understanding the interactions between organisms and environments, but such practices are strongly limited by the availability of phylogenetic frameworks. The tomocerin springtails are an ancient, widespread and ecologically important group of terrestrial arthropods, whereas their phylogeny and trait evolution remained unaddressed. In the present study, we conducted the first comprehensive phylogenetic reconstruction of Tomocerinae, based on a multi-loci molecular dataset covering all major lineages within the subfamily, using Bayesian inference (BI), maximum-likelihood (ML) and maximum-parsimony (MP) approaches. Divergence time was estimated and ancestral character state reconstruction (ACSR) was performed to trace the evolutionary history of five ecomorphological traits correlated with sensory and locomotory functions. Our results support the monophyly of Tomocerinae, and indicate that current classification of Tomocerinae only partially reflects evolutionary relationships, notably the commonest and speciose genus Tomocerus is polyphyletic. The subfamily probably originated in Early Cretaceous and diversified in two Cretaceous and one Eocene radiation events. As indicated by the evolutionary patterns of functional traits, multiple ecological divergences took place during the diversification of Tomocerinae. The study suggests a potential underestimation of ecological divergence and functional diversity in terrestrial arthropods, calls for an update of present trait databases, and demonstrates the value of macroevolutionary knowledge for improving the trait-based ecology. In addition, Tomocerus, Tomocerina and Tritomurus are redefined, a new genus Yoshiicerusgen. n. and new subgenera Coloratomurussubgen. n., Ciliatomurussubgen. n., Striatomurussubgen. n. and Ocreatomurussubgen. n. are described in the appendix.

Plant-mediated effects of elevated CO2 and rice cultivars on soil carbon dynamics in a paddy soil.

Soil organic carbon (SOC) sequestration under elevated CO2 concentration (eCO2 ) is a function of carbon (C) input and C retention. Nitrogen (N) limitation in natural ecosystems can constrain plant responses to eCO2 and their subsequent effects on SOC, but the effect of eCO2 on SOC in N-enriched agroecosystems with cultivars highly responsive to eCO2 is largely unknown. We reported results of SOC dynamics from a field free-air CO2 enrichment experiment with two rice cultivars having distinct photosynthetic capacities under eCO2 . A reciprocal incubation experiment was further conducted to disentangle the effect of changes in litter quality and soil microbial community on litter-derived C dynamics. eCO2 significantly increased total SOC content, dissolved organic C and particulate organic C under the strongly responsive cultivar, likely due to enhanced organic C inputs originated from CO2 stimulation of shoot and root biomass. Increases in the residue C : N ratio and fungal abundance induced by eCO2 under the strongly responsive cultivar reduced C losses from decomposition, possibly through increasing microbial C use efficiency. Our findings suggest that applications of high-yielding cultivars may substantially enhance soil C sequestration in rice paddies under future CO2 scenarios.

Agriculture erases climate constraints on soil nematode communities across large spatial scales.

Anthropogenic conversion of natural to agricultural land reduces aboveground biodiversity. Yet, the overall consequences of land-use changes on belowground biodiversity at large scales remain insufficiently explored. Furthermore, the effects of conversion on different organism groups are usually determined at the taxonomic level, while an integrated investigation that includes functional and phylogenetic levels is rare and absent for belowground organisms. Here, we studied the Earth's most abundant metazoa-nematodes-to examine the effects of conversion from natural to agricultural habitats on soil biodiversity across a large spatial scale. To this aim, we investigated the diversity and composition of nematode communities at the taxonomic, functional, and phylogenetic level in 16 assemblage pairs (32 sites in total with 16 in each habitat type) in mainland China. While the overall alpha and beta diversity did not differ between natural and agricultural systems, all three alpha diversity facets decreased with latitude in natural habitats. Both alpha and beta diversity levels were driven by climatic differences in natural habitats, while none of the diversity levels changed in agricultural systems. This indicates that land conversion affects soil biodiversity in a geographically dependent manner and that agriculture could erase climatic constraints on soil biodiversity at such a scale. Additionally, the functional composition of nematode communities was more dissimilar in agricultural than in natural habitats, while the phylogenetic composition was more similar, indicating that changes among different biodiversity facets are asynchronous. Our study deepens the understanding of land-use effects on soil nematode diversity across large spatial scales. Moreover, the detected asynchrony of taxonomic, functional, and phylogenetic diversity highlights the necessity to monitor multiple facets of soil biodiversity in ecological studies such as those investigating environmental changes.

Probing active microbes involved in Bt-containing rice straw decomposition.

Transgenic Bacillus thuringiensis (Bt) rice extends significant protection against insect pests and meets the increasing demands for food and energy. Many studies have been conducted investigating the impacts of Bt rice to the agricultural ecosystem, but much less attention has been given to efforts attempting to determine how the presence of Bt rice influences and shapes the microbial community, especially the active microbes. Stable isotope probing and high-throughput sequencing were employed to explore the active microbes involved in Bt-containing straw decomposition. Compared to its near isoline, the Bt straw contained higher contents of total N, total P, total K, lignin, cellulose, and Cry1Ab toxin protein. These chemical differences did not affect the decomposition rate but significantly changed the active microbial decomposer communities. During the decomposition of Bt-containing straw, fungi were more affected than bacteria. Agromyces, Terrabacter, Microbacterium, Glycomyces, and Kribbella were the most representative unique (existed only in the Bt treatments and appeared at the early stage) bacterial genera, and Trichoderma was the most representative unique fungal genus in the Bt straw decomposition. By using similarity index calculation and function prediction, the significant differences between Bt straw and non-Bt straw treatments were found to be transient for both microbial taxa and functional traits. These results suggested that Bt rice has a significant but transient impact on soil microbes in terms of microbial straw decomposition.

Phylogenetic evaluation of Amynthas earthworms from South China reveals the initial ancestral state of spermathecae.

Our knowledge of the phylogeny of the earthworm genus Amynthas under the family Megascolecidae, which is comprised of a huge number of species, is very limited compared to the better-known and much smaller family Lumbricidae. In order to investigate the phylogenetic relationships among the species within the genus Amynthas, which is the largest genus of the Megascolecidae family, nuclear and mitochondrial DNA sequences of 77 species, including 76 in-group Amynthas species collected from South China and 1 out-group species, were analyzed. A 5402bp segments composed of whole nuclear 18S rDNA and the mitochondrial genes COI, COII, ND1, 12S, and 16S was assembled from 77 species. Maximum Likelihood and Bayesian analyses of the concatenated sequences were performed. The results revealed evolution of two geographically independent lineages, both showing the ancestral state of two pairs of spermatheca (Sp.p 7/8/9). We found the species groups described by Sims and Easton (1972) to be non-monophyletic, and the origin of the parthenogenetic species group to likely be a quadthecal ancestor. These results provide modest evidence in support of an Indochinese peninsula origin of the Chinese Amynthas species and divergence of the genus once it had spread to mainland China. The findings of this study are consistent with a divergence scenario that resulted in at least one branch spreading to the Southeast of China and another branch spreading to the Southwest of China, but further research is required to confirm this interpretation of the Amynthas phylogeny.

Different effects of invader-native phylogenetic relatedness on invasion success and impact: a meta-analysis of Darwin's naturalization hypothesis.

Darwin's naturalization hypothesis (DNH), which predicts that alien species more distantly related to native communities are more likely to naturalize, has received much recent attention. The mixed findings from empirical studies that have tested DNH, however, seem to defy generalizations. Using meta-analysis to synthesize results of existing studies, we show that the predictive power of DNH depends on both the invasion stage and the spatial scale of the studies. Alien species more closely related to natives tended to be less successful at the local scale, supporting DNH; invasion success, however, was unaffected by alien-native relatedness at the regional scale. On the other hand, alien species with stronger impacts on native communities tended to be more closely related to natives at the local scale, but less closely related to natives at the regional scale. These patterns are generally consistent across different ecosystems, taxa and investigation methods. Our results revealed the different effects of invader-native relatedness on invader success and impact, suggesting the operation of different mechanisms across invasion stages and spatial scales.

Linking nematodes and ecosystem function: a trait-based framework.

Trait-based approaches are being increasingly adopted to understand species' ecological strategies and how organisms influence ecosystem function. Trait-based research on soil organisms, however, remains poorly developed compared with that for plants. The abundant and diverse soil nematodes are prime candidates to advance trait-based approaches belowground, but a unified trait framework to describe nematode ecological strategies and assess their linkages with ecosystem function is lacking. We categorized nematode traits as morphological, physiological, life history, and community clusters, and proposed the nematode economics spectrum (NES) to better understand nematode ecological strategies and their association with ecosystem function. We argue that bridging the NES and the plant economics spectrum will facilitate a more holistic understanding of ecosystem carbon and nutrient cycling under global change.

Highly Concentrated Electrolyte Superlubricants Enhanced by Interfacial Water Competition Around Chemically Active MgO Additives.

The low concentration of water-based lubricants and the high chemical inertness of the additives involved are often regarded as basic norms in the design of liquid lubricants. Herein, a novel liquid superlubricant of an aqueous solution containing a relatively high concentration of salt, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), is reported for the first time, and the superlubricity stability and load-bearing capacity of the optimized system (MgO0.10/LiTFSI10) are effectively strengthened by the addition of only trace (0.10 wt %) water-chemically active MgO additives. It demonstrates higher applicable loads, lower COF (∼0.004), and stability relative to the base solution. Only a trace amount of MgO additive is needed for the superlubricity, which makes up for the cost and environmental deficiencies of LiTFSI10. The weak interaction region between free water and the outer-layer water of Li+ hydration shells becomes a possible ultralow shear resistance sliding interface; the Mg(OH)2 layer, generated by the reaction of MgO with water, further creates additional weakly interacting interfaces, leading to the formation of an asymmetric contact between the clusters/particles within the hydrodynamic film by moderating the competition between interfacial water and free water, thus achieving high load-bearing macroscopic superlubricity. This study deepens the contribution of electrolyte concentration to ionic hydration and superlubricity due to the low shear slip layer formed by interfacial water competition with water-activated solid additives, providing new insights into the next generation of high load-bearing water-based liquid superlubricity systems.

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Functional traits are indicators of the responses and adaptation of organisms to environmental changes and cascade to a series of ecosystem functions. The functional traits of soil animals are sensitive to environmental factors and may characterize and predict the changes of ecosystem functions. Multiple dimensions of biodiversity that combing species, phylogenetic, and functional diversity improves the understanding of distribution patterns, community assembly mechanisms and ecosystem functions of soil animals. In this review, we listed the categories of soil animal functional traits and their ecological significance, and summarized current researches on the responses of soil animal communities to environmental changes and the community assembly processes based on trait-based approaches. We proposed to strengthen the study on the impacts of eco-evolution processes of biotic interactions to soil animal functional traits, establish the database of soil animal functional traits, and apply trait-based approaches in the ecological restoration in the future, which would benefit soil biodiversity conservation and sustainability of soil ecosystems.

Nutrient-induced acidification modulates soil biodiversity-function relationships.

Nutrient enrichment is a major global change component that often disrupts the relationship between aboveground biodiversity and ecosystem functions by promoting species dominance, altering trophic interactions, and reducing ecosystem stability. Emerging evidence indicates that nutrient enrichment also reduces soil biodiversity and weakens the relationship between belowground biodiversity and ecosystem functions, but the underlying mechanisms remain largely unclear. Here, we explore the effects of nutrient enrichment on soil properties, soil biodiversity, and multiple ecosystem functions through a 13-year field experiment. We show that soil acidification induced by nutrient enrichment, rather than changes in mineral nutrient and carbon (C) availability, is the primary factor negatively affecting the relationship between soil diversity and ecosystem multifunctionality. Nitrogen and phosphorus additions significantly reduce soil pH, diversity of bacteria, fungi and nematodes, as well as an array of ecosystem functions related to C and nutrient cycling. Effects of nutrient enrichment on microbial diversity also have negative consequences at higher trophic levels on the diversity of microbivorous nematodes. These results indicate that nutrient-induced acidification can cascade up its impacts along the soil food webs and influence ecosystem functioning, providing novel insight into the mechanisms through which nutrient enrichment influences soil community and ecosystem properties.

Long-term organic amendments increase the vulnerability of microbial respiration to environmental changes: Evidence from field and laboratory studies.

Organic amendments can improve soil fertility and microbial diversity, making agroecosystems more resilient to stress. However, it is uncertain whether organic amendments will enhance the functional capacity of soil microbial communities, thereby mitigating fluctuations in microbial respiration caused by environmental changes. Here, we examined the impacts of long-term organic amendments on the dynamics of microbial catabolic capacity (characterized by enzyme activities and carbon source utilization) and microbial respiration, as well as their interrelationships during a period with fluctuating temperature and rainfall in the field. We then subjected the field soil samples to laboratory heating disturbances to further evaluate the importance of microbial catabolic capacity in explaining patterns of microbial respiration. In both field and laboratory experiments, organic amendments tended to increase the stability of microbial catabolic capacity, but significantly increased the vulnerability of microbial respiration to environmental changes. However, the direction and driving factors of microbial respiration affected by environmental changes differed between the field and laboratory experiments. Environmental changes in the field suppressed the promotional effects of organic amendments on microbial respiration mainly through reducing microbial catabolic capacity, while laboratory heating further enhanced microbial respiration mainly due to increased soil resource availability. Together, these findings suggest that increased microbial respiration variations under organic amendments may potentially increase the uncertainty in predicting soil carbon emissions in the scenario of ongoing climate/anthropogenic changes, and highlight the necessity of linking laboratory studies on environmental changes to field conditions.

Active microbial population dynamics and life strategies drive the enhanced carbon use efficiency in high-organic matter soils.

Microbial carbon use efficiency (CUE) is a critical parameter that controls carbon storage in soil, but many uncertainties remain concerning adaptations of microbial communities to long-term fertilization that impact CUE. Based on H218O quantitative stable isotope probing coupled with metagenomic sequencing, we disentangled the roles of active microbial population dynamics and life strategies for CUE in soils after a long-term (35 years) mineral or organic fertilization. We found that the soils rich in organic matter supported high microbial CUE, indicating a more efficient microbial biomass formation and a greater carbon sequestration potential. Organic fertilizers supported active microbial communities characterized by high diversity and a relative increase in net growth rate, as well as an anabolic-biased carbon cycling, which likely explains the observed enhanced CUE. Overall, these results highlight the role of population dynamics and life strategies in understanding and predicting microbial CUE and sequestration in soil.IMPORTANCEMicrobial CUE is a major determinant of global soil organic carbon storage. Understanding the microbial processes underlying CUE can help to maintain soil sustainable productivity and mitigate climate change. Our findings indicated that active microbial communities, adapted to long-term organic fertilization, exhibited a relative increase in net growth rate and a preference for anabolic carbon cycling when compared to those subjected to chemical fertilization. These shifts in population dynamics and life strategies led the active microbes to allocate more carbon to biomass production rather than cellular respiration. Consequently, the more fertile soils may harbor a greater microbially mediated carbon sequestration potential. This finding is of great importance for manipulating microorganisms to increase soil C sequestration.

Unravelling High-Load Superlubricity of Ionic Liquid Analogues by In Situ Raman: Incomplete Hydration Induced by Competitive Exchange of External Water with Crystalline Water.

A high load-carrying capacity is the key to the practicality of liquid superlubricity, but it is difficult to achieve high load and low friction simultaneously by relying solely on a liquid film. Herein, a choline chloride-based ionic liquid analogue (ILA) macroscale superlubricant is first reported by tuning down strong hydrogen bonding in the ILA via introducing 2-10 wt % water, with a high load of 160 MPa and a low coefficient of friction of 0.006-0.008. In situ Raman reveals that competitive exchange between external water and crystalline water induces weak H-bond-dominated incomplete hydration, conferring a low-shear interface and considerable load-carrying capacity inside the lubricant. It is a hydrodynamic lubrication film rather than a tribochemical/physical adsorption film, allowing it to be applied to friction pairs of various materials. This study unveils the principle of water mediation of high-viscosity ILAs and also provides new insights into the design of practical ILA-based superlubrication materials with high load-carrying capacity.