Temporal dynamics of Grime's CSR strategies in plant communities during 60 years of succession.

Grime's competitive, stress-tolerant, ruderal (CSR) theory predicts a shift in plant communities from ruderal to stress-tolerant strategies during secondary succession. However, this fundamental tenet lacks empirical validation using long-term continuous successional data. Utilizing a 60-year longitudinal data of old-field succession, we investigated the community-level dynamics of plant strategies over time. Our findings reveal that while plant communities generally transitioned from ruderal to stress-tolerant strategies during succession, initial abandonment conditions crucially shaped early successional strategies, leading to varied strategy trajectories across different fields. Furthermore, we found a notable divergence in the CSR strategies of alien and native species over succession. Initially, alien and native species exhibited similar ruderal strategies, but in later stages, alien species exhibited higher ruderal and lower stress tolerance compared to native species. Overall, our findings underscore the applicability of Grime's predictions regarding temporal shifts in CSR strategies depending on both initial community conditions and species origin.

Global freshwater fish invasion linked to the presence of closely related species.

In the Anthropocene, non-native freshwater fish introductions and translocations have occurred extensively worldwide. However, their global distribution patterns and the factors influencing their establishment remain poorly understood. We analyze a comprehensive database of 14953 freshwater fish species across 3119 river basins and identify global hotspots for exotic and translocated non-native fishes. We show that both types of non-native fishes are more likely to occur when closely related to native fishes. This finding is consistent across measures of phylogenetic relatedness, biogeographical realms, and highly invaded countries, even after accounting for the influence of native diversity. This contradicts Darwin's naturalization hypothesis, suggesting that the presence of close relatives more often signifies suitable habitats than intensified competition, predicting the establishment of non-native fish species. Our study provides a comprehensive assessment of global non-native freshwater fish patterns and their phylogenetic correlates, laying the groundwork for understanding and predicting future fish invasions in freshwater ecosystems.

A latitudinal gradient in Darwin's naturalization conundrum at the global scale for flowering plants.

Darwin's naturalization conundrum describes two seemingly contradictory hypotheses regarding whether alien species closely or distantly related to native species should be more likely to naturalize in regional floras. Both expectations have accumulated empirical support, and whether such apparent inconsistency can be reconciled at the global scale is unclear. Here, using 219,520 native and 9,531 naturalized alien plant species across 487 globally distributed regions, we found a latitudinal gradient in Darwin's naturalization conundrum. Naturalized alien plant species are more closely related to native species at higher latitudes than they are at lower latitudes, indicating a greater influence of preadaptation in harsher climates. Human landscape modification resulted in even steeper latitudinal clines by selecting aliens distantly related to natives in warmer and drier regions. Our results demonstrate that joint consideration of climatic and anthropogenic conditions is critical to reconciling Darwin's naturalization conundrum.

Scale-dependent changes in ecosystem temporal stability over six decades of succession.

A widely assumed, but largely untested, tenet in ecology is that ecosystem stability tends to increase over succession. We rigorously test this idea using 60-year continuous data of old field succession across 480 plots nested within 10 fields. We found that ecosystem temporal stability increased over succession at the larger field scale (γ stability) but not at the local plot scale (α stability). Increased spatial asynchrony among plots within fields increased γ stability, while temporal increases in species stability and decreases in species asynchrony offset each other, resulting in no increase in α stability at the local scale. Furthermore, we found a notable positive diversity-stability relationship at the larger but not local scale, with the increased γ stability at the larger scale associated with increasing functional diversity later in succession. Our results emphasize the importance of spatial scale in assessing ecosystem stability over time and how it relates to biodiversity.

Darwin's naturalization conundrum reconciled by changes of species interactions.

Although phylogenetic distance between native and exotic species has a close link with their interactions, it is still unclear how environmental stresses and species interactions influence the relationship between phylogenetic distance and biological invasions. Here we assessed the effect of invader-native phylogenetic distance on the growth of the invader (Symphyotrichum subulatum) under three levels of drought (no, moderate, or intense drought). Under no drought, interspecific competition between close relatives was the dominant process and native communities more closely related to the invader showed higher resistance to invasion, supporting Darwin's naturalization hypothesis. In contrast, under intense drought, facilitation between close relatives by mutualism with arbuscular mycorrhizal fungi (AMF) became more important, and the invader became more successful in their more closely related native communities, supporting the preadaptation hypothesis. The colonization rate of AMF of the invader was higher in more closely related native communities regardless of the drought treatment, but it was only positively related to invader biomass under intense drought. Therefore, the shift of species interactions from competition to facilitation may be ascribed to the promotion of AMF to invasion occurring under intense drought, which leads to the effect of closely related natives on the invader shifting from negative to positive. Our results provide a new angle to resolve Darwin's naturalization conundrum from the change of species interactions along a stress gradient, and provide important clues for invasion management when species interactions change in response to global climatic change.

Spatial scaling of soil microbial co-occurrence networks in a fragmented landscape.

Habitat loss has been a primary threat to biodiversity. However, species do not function in isolation but often associate with each other and form complex networks. Thus, revealing how the network complexity and stability scale with habitat area will give us more insights into the effects of habitat loss on ecosystems. In this study, we explored the relationships between the island area and the network complexity and stability of soil microbes. We found that the complexity and stability of soil microbial co-occurrence networks scale positively with island area, indicating that habitat loss will potentially simplify and destabilize soil microbial networks.

Exotic fishes that are phylogenetically close but functionally distant to native fishes are more likely to establish.

Since Darwin's time, degree of ecological similarity between exotic and native species has been assumed to affect the establishment success or failure of exotic species. However, a direct test of the effect of exotic-native similarity on establishment of exotics is scarce because of the difficulty in recognizing failures of species to establish in the field. Here, using a database on the establishment success and failure of exotic fish species introduced into 673 freshwater lakes, we evaluate the effect of similarity on the establishment of exotic fishes by combining phylogenetic and functional information. We illustrate that, relative to other biotic and abiotic factors, exotic-native phylogenetic and functional similarities were the most important correlates of exotic fish establishment. While phylogenetic similarity between exotic and resident fish species promoted successful establishment, functional similarity led to failure of exotics to become established. Those exotic species phylogenetically close to, but functionally distant from, native fishes were most likely to establish successfully. Our findings provide a perspective to reconcile Darwin's naturalization conundrum and suggest that, while phylogenetic relatedness allows exotic fish species to pre-adapt better to novel environments, they need to possess distinct functional traits to reduce competition with resident native fish species.

Imaging presentation of biliary adenofibroma: A case report.

BACKGROUND: Biliary adenofibroma (BF) is a rare benign epithelial tumor with the possibility of malignant transformation. Its main pathological feature is a well-defined cystic or honeycomb mass. BF has no specific clinical manifestations or laboratory and imaging findings; thus, it is easily misdiagnosed before surgery. This report describes a case in which biliary cystadenoma was misdiagnosed preoperatively and BF was diagnosed postoperatively. The imaging features, particularly the magnetic resonance imaging (MRI) features, were analyzed and summarized. CASE SUMMARY: A 68-year-old Chinese man was admitted to our hospital with a 2-mo history of abdominal discomfort. Following admission to our hospital, laboratory examinations showed normal tumor marker concentrations and liver function. Hepatocellular carcinoma was considered after contrast-enhanced ultrasound examination. MRI suggested the possibility of cystadenoma of the bile duct. However, postoperative pathological examination confirmed the diagnosis of BF. No local recurrence was found 1 mo after surgery. CONCLUSION: Our objective is to highlight the imaging diagnostic value of BF, especially on an MRI enhanced scan with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid.

Functional traits explain the consistent resistance of biodiversity to plant invasion under nitrogen enrichment.

Elton's biotic resistance hypothesis, which posits that diverse communities should be more resistant to biological invasions, has received considerable experimental support. However, it remains unclear whether such a negative diversity-invasibility relationship would persist under anthropogenic environmental change. By using the common ragweed (Ambrosia artemisiifolia) as a model invader, our 4-year grassland experiment demonstrated consistently negative relationships between resident species diversity and community invasibility, irrespective of nitrogen addition, a result further supported by a meta-analysis. Importantly, our experiment showed that plant diversity consistently resisted invasion simultaneously through increased resident biomass, increased trait dissimilarity among residents, and increased community-weighted means of resource-conservative traits that strongly resist invasion, pointing to the importance of both trait complementarity and sampling effects for invasion resistance even under resource enrichment. Our study provides unique evidence that considering species' functional traits can help further our understanding of biotic resistance to biological invasions in a changing environment.

2D van der Waals materials for ultrafast pulsed fiber lasers: review and prospect.

2D van der Waals materials are crystals composed of atomic layers, which have atomic thickness scale layers and rich distinct properties, including ultrafast optical response, surface effects, light-mater interaction, small size effects, quantum effects and macro quantum tunnel effects. With the exploration of saturable absorption characteristic of 2D van der Waals materials, a series of potential applications of 2D van der Waals materials as high threshold, broadband and fast response saturable absorbers (SAs) in ultrafast photonics have been proposed and confirmed. Herein, the photoelectric characteristics, nonlinear characteristic measurement technique of 2D van der Waals materials and the preparation technology of SAs are systematically described. Furthermore, the ultrafast pulsed fiber lasers based on classical 2D van der Waals materials including graphene, transition metal chalcogenides, topological insulators and black phosphorus have been fully summarized and analyzed. On this basis, opportunities and directions in this field, as well as the research results of ultrafast pulsed fiber lasers based on the latest 2D van der Waals materials (such as PbO, FePSe3, graphdiyne, bismuthene, Ag2S and MXene etc), are reviewed and summarized.

Island biogeography of soil bacteria and fungi: similar patterns, but different mechanisms.

Microbes, similar to plants and animals, exhibit biogeographic patterns. However, in contrast with the considerable knowledge on the island biogeography of higher organisms, we know little about the distribution of microorganisms within and among islands. Here, we explored insular soil bacterial and fungal biogeography and underlying mechanisms, using soil microbiota from a group of land-bridge islands as a model system. Similar to island species-area relationships observed for many macroorganisms, both island-scale bacterial and fungal diversity increased with island area; neither diversity, however, was affected by island isolation. By contrast, bacterial and fungal communities exhibited strikingly different assembly patterns within islands. The loss of bacterial diversity on smaller islands was driven primarily by the systematic decline of diversity within samples, whereas the loss of fungal diversity on smaller islands was driven primarily by the homogenization of community composition among samples. Lower soil moisture limited within-sample bacterial diversity, whereas smaller spatial distances among samples restricted among-sample fungal diversity, on smaller islands. These results indicate that among-island differences in habitat quality generate the bacterial island species-area relationship, whereas within-island dispersal limitation generates the fungal island species-area relationship. Together, our study suggests that different mechanisms underlie similar island biogeography patterns of soil bacteria and fungi.

Mechanisms of soil bacterial and fungal community assembly differ among and within islands.

The study of islands has made substantial contributions to the development of evolutionary and ecological theory. However, we know little about microbial community assembly on islands. Using soil microbial data collected from 29 lake islands and nearby mainland, we examined the assembly mechanisms of soil bacterial and fungal communities among and within islands. We found that deterministic processes, especially homogeneous selection, tended to be more important in shaping the assembly of soil bacterial communities among islands, while stochastic processes tended to be more important within islands. Moreover, increasing island area increased the importance of homogeneous selection, but reduced the importance of variable selection, for soil bacterial community assembly within islands. By contrast, stochastic processes tended to dominate soil fungal community assembly both among and within islands, with dispersal limitation playing a more important role within than among islands. Our results highlight the scale- and taxon-dependence of insular soil microbial community assembly, suggesting that spatial scale should be explicitly considered when evaluating the influences of habitat fragmentation on soil microbial communities.

Increased snowfall weakens complementarity of summer water use by different plant functional groups.

Winter snowfall is an important water source for plants during summer in semiarid regions. Snow, rain, soil water, and plant water were sampled for hydrogen and oxygen stable isotopes analyses under control and increased snowfall conditions in the temperate steppe of Inner Mongolia, China. Our study showed that the snowfall contribution to plant water uptake continued throughout the growing season and was detectable even in the late growing season. Snowfall versus rainfall accounted for 30% and 70%, respectively, of the water source for plants, on the basis of hydrogen stable isotope signature (δD) analysis, and accounted for 12% and 88%, respectively, on the basis of oxygen stable isotope signature (δ18O) analysis. Water use partitioning between topsoil and subsoil was found among species with different rooting depths. Increased snowfall weakened complementarity of plant water use during summer. Our study provides insights into the relationships between precipitation regimes and species interactions in semiarid regions.

Polyacetylenes from the Roots of Swietenia macrophylla King.

A phytochemical investigation of the roots of Swietenia macrophylla led to the isolation of seven polyacetylenes, including five new compounds (1-5) and two known ones (6-7). Their structures were elucidated by extensive spectroscopic analysis and detailed comparison with reported data. All the isolates were tested for their cytotoxicity against the human hepatocellular carcinoma cell line BEL-7402, human myeloid leukemia cell line K562, and human gastric carcinoma cell line SGC-7901. Compounds 1 and 6 showed moderate cytotoxicity against the above three human cancer cell lines with IC50 values ranging from 14.3 to 45.4 µM. Compound 4 displayed cytotoxicity against the K562 and SGC-7901 cancer cell lines with IC50 values of 26.2 ± 0.4 and 21.9 ± 0.3 µM, respectively.

The chemokine CXCL1 and its receptor CXCR2 contribute to chronic stress-induced depression in mice.

Depression is increasingly recognized as an inflammatory disease, with inflammatory crosstalk in the brain contributing its pathogenesis. Life stresses may up-regulate inflammatory processes and promote depression. Although cytokines are central to stress-related immune responses, their contribution to stress-induced depression remains unclear. Here, we used unpredictable chronic mild stress (UCMS) to induce depression-like behaviors in mice, as assessed through a suite of behavioral tests. C-X-C motif chemokine ligand 1 (CXCL1)-related molecular networks responsible for depression-like behaviors were assessed through intrahippocampal microinjection of lenti-CXCL1, the antidepressant fluoxetine, the C-X-C motif chemokine receptor 2 (CXCR2) inhibitor SB265610, and the glycogen synthase kinase-3ß (GSK3ß) inhibitor AR-A014418. Modulation of apoptosis-related pathways and neuronal plasticity were assessed via quantification of cleaved caspase-3, B-cell lymphoma 2-associated X protein, cAMP response element-binding protein (CREB), and brain-derived neurotrophic factor (BDNF) protein expression. CXCL1/CXCL2 expression was correlated with depression-like behaviors in response to chronic stress or antidepressant treatment in the UCMS depression model. Intrahippocampal microinjection of lenti-CXCL1 increased depression-like behaviors, activated GSK3ß, increased apoptosis pathways, suppressed CREB activation, and decreased BDNF. Administration of the selective GSK3ß inhibitor AR-A014418 abolished the effects of lenti-CXCL1, and the CXCR2 inhibitor SB265610 prevented chronic stress-induced depression-like behaviors, inhibited GSK3ß activity, blocked apoptosis pathways, and restored BDNF expression. The CXCL1/CXCR2 axis appears to play a critical role in stress-induced depression, and CXCR2 is a potential novel therapeutic target for patients with depression.-Chai, H.-H., Fu, X.-C., Ma, L., Sun, H.-T., Chen, G.-Z., Song, M.-Y., Chen, W.-X., Chen, Y.-S., Tan, M.-X., Guo, Y.-W., Li, S.-P. The chemokine CXCL1 and its receptor CXCR2 contribute to chronic stress-induced depression in mice.

Two new compounds from the roots of Swietenia macrophylla.

Phytochemical investigation on the roots of Swietenia macrophylla yielded one new pharagmalin-type limonoid named 2-dehydroxyl-swietephragmin C (1) and one new xanthone, 1,5-dihydroxy-6-methoxy-6',6'-dimethyl-2H-pyrano[2',3':3,2]xanthone (2), in addition to three known compounds. The structures of the new compounds were unambiguously determined by comprehensive spectroscopic methods (NMR, UV, IR, MS), as well as by comparison with the reported data in the literature. Xanthones were reported from Swietenia genus for the first time.

Niche and fitness differences determine invasion success and impact in laboratory bacterial communities.

There is increasing awareness of invasion in microbial communities worldwide, but the mechanisms behind microbial invasions remain poorly understood. Specifically, we know little about how the evolutionary and ecological differences between invaders and natives regulate invasion success and impact. Darwin's naturalization hypothesis suggests that the phylogenetic distance between invaders and natives could be a useful predictor of invasion, and modern coexistence theory proposes that invader-native niche and fitness differences combine to determine invasion outcome. However, the relative importance of phylogenetic distance, niche difference and fitness difference for microbial invasions has rarely been examined. By using laboratory bacterial microcosms as model systems, we experimentally assessed the roles of these differences for the success of bacterial invaders and their impact on native bacterial community structure. We found that the phylogenetic distance between invaders and natives failed to explain invasion success and impact for two of three invaders at the phylogenetic scale considered. Further, we found that invasion success was better explained by invader-native niche differences than relative fitness differences for all three invaders, whereas invasion impact was better explained by invader-native relative fitness differences than niche differences. These findings highlight the utility of considering modern coexistence theory to gain a more mechanistic understanding of microbial invasions.

Differential roles of species richness versus species asynchrony in regulating community stability along a precipitation gradient.

Plant community may provide products and services to humans. However, patterns and drivers of community stability along a precipitation gradient remain unclear. A regional-scale transect survey was conducted over a 3-year period from 2013 to 2015, along a precipitation gradient from 275 to 555 mm and spanning 440 km in length from west to east in a temperate semiarid grassland of northern China, a central part of the Eurasian steppe. Our study provided regional-scale evidence that the community stability increased with increasing precipitation in the semiarid ecosystem. The patterns of community stability along a precipitation gradient were ascribed to community composition and community dynamics, such as species richness and species asynchrony, rather than the abiotic effect of precipitation. Species richness regulated the temporal mean (µ) of aboveground net primary productivity (ANPP), while species asynchrony regulated the temporal standard deviation (σ) of ANPP, which in turn contributed to community stability. Our findings highlight the crucial role of community composition and community dynamics in regulating community stability under climate change.

Preadaptation and Naturalization of Nonnative Species: Darwin's Two Fundamental Insights into Species Invasion.

Predicting which nonnative species become invasive is critical for their successful management, and Charles Darwin provided predictions based on species' relatedness. However, Darwin provided two opposing predictions about the relatedness of introduced nonnatives to indigenous species. First, environmental fit is the dominant factor determining invader success; thus, we should expect that invasive species are closely related to local native residents. Alternatively, if competition is important, we should expect successful invaders are distantly related to the native residents. These opposing expectations are referred to as Darwin's naturalization conundrum. The results of studies that examine nonnative species relatedness to natives are largely inconsistent. This inconsistency arises from the fact that studies occur at different spatial and temporal scales, and at different stages of invasion, and so implicitly examine different mechanisms. Further, while species have evolved ecological differences, the mode and tempo of evolution can affect species' differences, complicating the predictions from simple hypotheses. We outline unanswered questions and provide guidelines for collecting the data required to test competing hypotheses.

Are Hong Kong and Taiwan stepping-stones for invasive species to the mainland of China?

Understanding the origins and introduction pathways of invasive species is a fundamental issue for invasion biology, which is necessary for predicting and preventing future invasion. Once an invasive species is established in a new location, this location could serve as a stepping-stone for further invasions. However, such "stepping-stone" effect has not been widely investigated. Using the published literature and records, we compiled the first found locations of 127 top invasive species in China. Our study showed that the most common landing spots of these invasive species were Hong Kong (22 species) and Taiwan (20 species), which accounted for one-third of the invasive species in China. Our analysis revealed that the invasive species in mainland China were more likely to transport from Hong Kong than Macau, a neighboring region with a similar area and colonial history. Similarly, more invasive species were also first landed on Taiwan than Hainan, a nearby island sharing similar climate conditions. Together, our findings indicate that Hong Kong and Taiwan are the most important stepping-stones for invasive species to the mainland of China and suggesting that the increasing trade exchange of China's coastal ports constitutes a potential risk for the spread of more invasive species. We suppose that they would be the future stepping-stones for invasive species to the mainland of China and these coastal ports regions where improved biosecurity is needed now.