As a fast emerging topic, van der Waals (vdW) heterostructures have been proposed to modify two-dimensional layered materials with desired properties, thus greatly extending the applications of these ...materials. In this work, the stacking characteristics, electronic structures, band edge alignments, charge density distributions and optical properties of blue phosphorene/transition metal dichalcogenides (BlueP/TMDs) vdW heterostructures were systematically studied based on vdW corrected density functional theory. Interestingly, the valence band maximum and conduction band minimum are located in different parts of BlueP/MoSe2, BlueP/WS2 and BlueP/WSe2 heterostructures. The MoSe2, WS2 or WSe2 layer can be used as the electron donor and the BlueP layer can be used as the electron acceptor. We further found that the optical properties under visible-light irradiation of BlueP/TMDs vdW heterostructures are significantly improved. In particular, the predicted upper limit energy conversion efficiencies of BlueP/MoS2 and BlueP/MoSe2 heterostructures reach as large as 1.16% and 0.98%, respectively, suggesting their potential applications in efficient thin-film solar cells and optoelectronic devices.
Agricultural activity associated with habitat conversion is a major driver of biodiversity loss across the tropics. The decline of species richness is a common outcome of conversion to agricultural ...land use, but the associated changes in functional and phylogenetic diversities, and spatial patterns of beta diversity, are not well understood. These patterns may shed light on underlying ecological processes that are of both basic and applied interest; for example the relative roles of stochastic assembly, ecological filtering, and competition in structuring ecological communities as well as broader consequences for ecological functioning in agroecosystems. Here we investigate the effects of conversion to rubber plantation (Hevea brasiliensis), a rapidly spreading agroecosystem in Southeast Asia, on leaf-litter ant taxonomic, functional, and phylogenetic diversities at local and among-sites scales in Xishuangbanna, Southeast China. We found a sharp decline of ant species richness in rubber plantations compared with nearby forest habitat, with low beta diversity indicating spatial homogeneity of communities in rubber plantations. In addition, patterns of both functional alpha and beta diversities suggested the emergence of a functionally distinct ant community in the agroecosystem compared to the forest habitats. These results support a role of ecological filtering in structuring the taxonomic and functional composition of both rubber and forest habitats. In contrast, changes in phylogenetic diversity were modest and not significantly different from random expectations despite strong phylogenetic signal of functional traits. This study highlights the need for a pluralistic approach to characterizing the loss of biodiversity in agroecosystems, as well as understanding the underlying mechanisms of community assembly driving this biodiversity loss.
In this study, amino modified mesoporous silica (HMS-TEEPA-TEA) was used for the first time to remove uranium (VI) from aqueous solution. The synthesized HMS-TEEPA-TEA was characterized by SEM, EDS, ...FTIR, BET and XPS techniques. The present work attempted to optimize and compare the adsorption process parameters like pH, adsorbate concentration, and adsorbent dose using Box-Behnken designs of response surface methodology. The adsorption amount and removal rate reached 337.26 mg/g and 99.57%, respectively. Model P> F < 0.0001 in this experiment (generally P > F < 0.05 is considered significant), indicating that the model is extremely significant and can be considered as highly referable for its predicted response values. The fit of the data to the Langmuir isotherm and the proposed secondary kinetics indicates that the adsorption process is monolayer and chemical in nature. The effect of copper on HMS-TEEPA-TEA adsorption is more complex than other background ions. The removal of uranium (VI) by HMS-TEEPA-TEA remained above 80% for four consecutive experiments with repeated adsorbent use. The results indicate that HMS-TEEPA-TEA is an effective adsorbent for the removal of uranium (VI) from aqueous solutions with the advantages of low cost, high availability and easy production.
Ecological interactions among plants, insect herbivores, and parasitoids are pervasive in nature and play important roles in community assembling, but the codiversification of tri‐trophic ...interactions has received less attention. Here we compare pairwise codiversification patterns between a set of 22 fig species, their herbivorous pollinating and galling wasps, and their parasitoids. The parasitoid phylogeny showed significant congruence and more cospeciation events with host insects phylogeny than with host plants. These results suggest that parasitoid phylogeny and speciation is more closely related to their host insects than to their host plants. The pollinating wasps hosted more parasitoid species than gallers and indicated a more intense interspecific competition among parasitoids associated with pollinators. Closer matching and fewer evolutionary host shifts were found between parasitoids and galler hosts than between parasitoids and pollinator hosts. These results suggest that interspecific competition among parasitoids, rather than resource availability of host wasps, is the main driver of the codiversification pattern in this community. Therefore, our study highlights the important role of interspecific competition among high trophic level insects in plant–insect tri‐trophic community assembling.
Understanding biodiversity patterns and their underlying mechanisms is of interest to ecologists, biogeographers and conservationists and is critically important for conservation efforts. The ...Indo-Burma hotspot features high species diversity and endemism, yet it also faces significant threats and biodiversity losses; however, few studies have explored the genetic structure and underlying mechanisms of Indo-Burmese species. Here, we conducted a comparative phylogeographic analysis of two closely related dioecious Ficus species, F. hispida and F. heterostyla, based on wide and intensive population sampling across Indo-Burma ranges, using chloroplast (psbA-trnH, trnS-trnG) and nuclear microsatellite (nSSR) markers, as well as ecological niche modeling.
The results indicated large numbers of population-specific cpDNA haplotypes and nSSR alleles in the two species. F. hispida showed slightly higher chloroplast diversity but lower nuclear diversity than F. heterostyla. Low-altitude mountainous areas of northern Indo-Burma were revealed to have high genetic diversity and high habitat suitability, suggesting potential climate refugia and conservation priority areas. Strong phylogeographic structure and a marked east‒west differentiation pattern were observed in both species, due to the interactions between biotic and abiotic factors. Interspecific dissimilarities at fine-scale genetic structure and asynchronized historical dynamics of east‒west differentiation between species were also detected, which were attributed to different species-specific traits.
We confirm hypothesized predictions that interactions between biotic and abiotic factors largely determine the patterns of genetic diversity and phylogeographic structure of Indo-Burmese plants. The east‒west genetic differentiation pattern observed in two targeted figs can be generalized to some other Indo-Burmese plants. The results and findings of this work will contribute to the conservation of Indo-Burmese biodiversity and facilitate targeted conservation efforts for different species.
Moving target tracking of sensor networks is an important application. The sensor nodes cooperate in the networks to discover the target, and the target’s perceptual information is feeded back to the ...user. In order to effectively reduce the network energy consumption and improve the tracking quality, a target tracking protocol is proposed based on two-stage sleep scheduling. The whole tracking process is divided into two stages in the protocol. According to the different requirements of node density, the different sleep scheduling mechanism is adopted. In this paper, the proposed protocol is further optimized to ensure the tracking quality while minimizing system energy consumption. Finally, the validity of the proposed protocol was verified with 36 sensor nodes.
Organisms exist within ecological networks, connected through interactions such as parasitism, predation and mutualism which can modify their abundance and distribution within habitat patches. ...Differential species responses make it hard to predict the influence of climate change at the community scale. Understanding the interplay between climate and biotic interactions can improve our predictions of how ecosystems will respond to current global warming.
We aim to understand how climate affects the multitrophic biotic interactions as well as the community structure using the enclosed communities of wasps associated with figs as study system.
To examine the presence and strength of multitrophic species interactions, we first characterized the multitrophic community of fig wasps associated with Ficus racemosa and then applied hierarchical joint species distribution models, fitted to community monitoring data. We further evaluated the effect of climate on individual species trends as well as interspecific interactions.
We found that the competitive balance shifted to favour non‐pollinating galling wasps and disadvantage the dominant pollinator in suboptimal conditions. Furthermore, suboptimal conditions for galling wasps facilitated the occurrence of their specialized parasitoid, as changes cascaded across trophic levels and led to alternative community structures. Our results highlight the role of how species interactions can be modified across multiple trophic levels in a fig wasp community according to climate.
摘要
生态系统中的各类生物通过寄生、捕食、互惠等相互作用组成生态网络，并相互影响与制约。由于不同物种外界变化的响应存在差异，在群落水平上预测气候变化对生物的影响一直是个难点。了解气候与物种间相互作用怎样共同作用于群落中的物种，有助于完善生态系统如何响应当前气候变暖的预测。
在该研究中，我们选用榕小蜂群落作为研究系统，目标揭示气候怎样影响多营养级生物互作体及其群落结构。
我们首先通过应用层级联合物种分布模型 (Hierarchical joint species distribution models) 分析了群落监测数据，检测了聚果榕多营养级榕小蜂群落多种种间互作的关系与强度。再进一步评估气候对单个物种动态及种间互作的影响。
研究发现:当处于非最佳气候条件时，同一营养级之间的种间竞争更倾向于非优势的非传粉造瘿小蜂，对优势的传粉榕小蜂不利；而且同一营养级之间竞争平衡的倾斜，通过跨营养级的级联效应促进了非传粉造瘿小蜂专性复寄生蜂的发生，从而导致群落结构的改变。结果强调了气候通过级联效应影响种间的不同互作关系，最终影响多营养级的榕小蜂群落。
By investigating the responses of fig wasp species to temperature shifts, this study highlights the central role of biotic interactions in determining the impact of climate on ecological communities.
The overuse of antibiotics in animal agriculture and medicine has caused a series of potential threats to public health. Macleaya cordata is a medicinal plant species from the Papaveraceae family, ...providing a safe resource for the manufacture of antimicrobial feed additive for livestock. The active constituents from M. cordata are known to include benzylisoquinoline alkaloids （BIAs） such as sanguinarine （SAN） and chelerythrine （CHE）, but their metabolic pathways have yet to be studied in this non-model plant. The active biosynthesis of SAN and CHE in M. cordata was first examined and confirmed by feeding ^13C-labeled tyrosine. To gain further insights, we de novo sequenced the whole genome of M. cordata, the first to be sequenced from the Papaveraceae family. The M. cordata genome covering 378 Mb encodes 22,328 predicted protein-coding genes with 43.5% being transposable elements. As a member of basal eudicot, M. cordata genome lacks the paleohexaploidy event that occurred in almost all eudicots. From the genomics data, a complete set of 16 metabolic genes for SAN and CHE biosynthesis was retrieved, and 14 of their biochemical activities were validated. These genomics and metabolic data show the conserved BIA metabolic pathways in M. cordata and provide the knowledge foundation for future productions of SAN and CHE by crop improvement or microbial pathway reconstruction.
Recently, flexible electrodes with biaxial/omnidirectional stretchability haveattracted significant attention. However, most existing pliable electrode materialscan be only stretched in one ...direction. In this work, an unexpected isotropic vander Waals （vdW） heterostructure is proposed, based on the assembly of two-dimensional crystals of anisotropic black phosphorene （BP） and transition metalcarbide （TIC2）. Using vdW-corrected density functional theory calculations, theBPFFiC2 vdW heterostructure was predicted to have excellent structural andmechanical stability, superior electrical conductivity, omnidirectional flexibility,and a high Li storage capacity. We have unraveled the physical origin of theexcellent stability, as well as the Li adsorption preferences of the lithiatedheterostructure, based on a three-step analysis of the stability of the Li-adsorptionprocesses. In addition, the BP/TiC2 vdW heterostructure can also be applied asthe anode material for flexible Na-ion batteries because of its high Na storagecapacity and strong Na binding. However, compared with Na adsorption, thecapacity is higher, and the adsorption energy is more negative for Li adsorption.Our findings provide valuable insights into the exploration of a rich variety ofvdW heterostructures for next-generation flexible energy storage devices.
It is thought that speciation in phytophagous insects is often due to colonization of novel host plants, because radiations of plant and insect lineages are typically asynchronous. Recent ...phylogenetic comparisons have supported this model of diversification for both insect herbivores and specialized pollinators. An exceptional case where contemporaneous plant-insect diversification might be expected is the obligate mutualism between fig trees (Ficus species, Moraceae) and their pollinating wasps (Agaonidae, Hymenoptera). The ubiquity and ecological significance of this mutualism in tropical and subtropical ecosystems has long intrigued biologists, but the systematic challenge posed by > 750 interacting species pairs has hindered progress toward understanding its evolutionary history. In particular, taxon sampling and analytical tools have been insufficient for large-scale cophylogenetic analyses. Here, we sampled nearly 200 interacting pairs of fig and wasp species from across the globe. Two supermatrices were assembled: on an average, wasps had sequences from 77% of 6 genes (5.6 kb), figs had sequences from 60% of 5 genes (5.5 kb), and overall 850 new DNA sequences were generated for this study. We also developed a new analytical tool, Jane 2, for event-based phylogenetic reconciliation analysis of very large data sets. Separate Bayesian phylogenetic analyses for figs and fig wasps under relaxed molecular clock assumptions indicate Cretaceous diversification of crown groups and contemporaneous divergence for nearly half of all fig and pollinator lineages. Event-based cophylogenetic analyses further support the codiversification hypothesis. Biogeographic analyses indicate that the present-day distribution of fig and pollinator lineages is consistent with a Eurasian origin and subsequent dispersal, rather than with Gondwanan vicariance. Overall, our findings indicate that the fig-pollinator mutualism represents an extreme case among plant-insect interactions of coordinated dispersal and long-term codiversification.
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