Can the physiological tolerance hypothesis explain herb richness patterns along an elevational gradient? A trait-based analysis

Many taxa show their highest species richness at intermediate elevations, but the underlying reasons for this remain unclear. Here, we suggest that the physiological tolerance hypothesis can explain species richness patterns along elevational gradients, and we used functional diversity to test this hypothesis. We analyzed herb species richness, functional diversity, and environmental conditions along a 1300 m elevational gradient in a temperate forest, Beijing, China. We found that herb richness exhibited a “hump-shaped” relationship with elevation, with peak richness at approximately 1800 m. Functional diversity showed a significant unimodal relationship with elevation. The duration of high temperatures (≥ 300C: DHT) was the best predictor for herb richness and functional diversity along the gradient from 1020 to 1800 m, which suggest richness is limited by high temperature at low elevations. While along the gradient from 1800 to 2300 m, the duration of low temperatures (≤ 0°C: DLT) was the most powerful explanatory variable, which indicated at high elevations, richness reduced due to low temperature. Our analyses showed that the functional diversity of traits related to drought-tolerance (leaf mass per area, leaf area, and leaf hardiness) exhibited negative relationships with DHT, while functional diversity of traits related to freezing-tolerance (leaf thickness and hair density) exhibited negative relationships with DLT. Taken together, our results demonstrated that the richness-elevation relationship is consistent with the physiological tolerance hypothesis: at low elevations, richness is limited by high temperatures, and at high elevations, richness is reduced due to low temperatures. We concluded that our results provide trait-based support for the physiological tolerance hypothesis, suggesting that mid-elevations offer the most suitable environmental conditions, thus higher numbers of species are able to persist

The Ecological Effects of Ant-Aphid Mutualism on Plants at a Large Spatial Scale

The protective ant-plant interaction has been considered as a model system in studying mutualistic interactions, but we know little about the ecological effects of the mutualism at relatively larger spatial scales. In this study, by excluding an aphid-tending ant species (Lasius fuliginosus) from all host oak trees (Quercus liaotungensis) in 20x20 m plots, we evaluated the effects of ants on herbivory, fruit production and leaf toughness of the host tree. Through a two years study, we found that ants have a significant anti-herbivory effect on the host tree, with no effects on fruit production. At the end of the growing season, leaf toughness for plants without ants increased significantly. This suggests that ants are reliable and effective bodyguards for plants at larger spatial scales. For plants, the possible tradeoff between different defensive strategies at larger scale should be focused in further works

Multi-hop Evidence Retrieval for Cross-document Relation Extraction

Relation Extraction (RE) has been extended to cross-document scenarios because many relations are not simply described in a single document. This inevitably brings the challenge of efficient open-space evidence retrieval to support the inference of cross-document relations, along with the challenge of multi-hop reasoning on top of entities and evidence scattered in an open set of documents. To combat these challenges, we propose MR.COD (Multi-hop evidence retrieval for Cross-document relation extraction), which is a multi-hop evidence retrieval method based on evidence path mining and ranking. We explore multiple variants of retrievers to show evidence retrieval is essential in cross-document RE. We also propose a contextual dense retriever for this setting. Experiments on CodRED show that evidence retrieval with MR.COD effectively acquires crossdocument evidence and boosts end-to-end RE performance in both closed and open settings.Comment: ACL 2023 (Findings

Interplay of temperature and woody cover shapes herb communities along an elevational gradient in a temperate forest in Beijing, China

Abiotic and biotic factors have the potential to alter herb communities, however, few studies consider feedback between them. This study explores how variation of species interaction and climatic conditions associated with changes in altitude affect herb community composition. We sampled accumulated temperatures of growth duration (June-November) (ATGD), maximum summer temperatures (MST) and herb community composition (herb height, abundance, richness) on non-gaps and forest-gaps site across an elevational gradient. A significant negative relationship was detected between MST and herb richness. The temperature of non-gaps was cooler than that of forest gaps, and overstory cover positively correlated with herb abundance. However, the ATGD exhibited a negative relationship with overstory cover, in that overstory cover decreased with ATGD. We suggested that temperature has a profound effect on height and richness of herb communities, while the overstory cover is moderating the effect of temperature on herb community structure and influence the abundance of herb community. Conversely, decreases in ATGD weakened the relative importance of overstory cover. We concluded that the interaction of temperature and overstory cover shapes the morphology, abundance and richness of herb communities

Ectopic Expression of PtoMYB74 in Poplar and Arabidopsis Promotes Secondary Cell Wall Formation

In vascular plants, R2R3-MYB transcription factors are important regulators of secondary cell wall formation. Although 192 annotated R2R3 MYB genes were identified in the poplar genome, only a few members were characterized to participate in the regulation of the secondary cell wall biosynthesis. In this paper, we identify an R2R3-MYB transcription factor, PtoMYB74, which is predicted to be an ortholog of Arabidopsis AtMYB61, a transcription activator that regulates the secondary cell wall formation, lignin biosynthesis, stomatal aperture, and the mucilage of seed coat. PtoMYB74 is mainly expressed in the stems, especially in the xylem tissues and organs. PtoMYB74 as a transcriptional activator is localized to the nucleus. The overexpression of PtoMYB74 increased the secondary cell wall thickness of vessels in transgenic poplar and changed the secondary cell wall compositions. The expression levels of lignin and cellulose biosynthetic genes were elevated in the transgenic poplar overexpressing PtoMYB74 compared to the wild type, while there was no change in the xylan biosynthetic genes. Transcriptional activation assays demonstrated that PtoMYB74 could activate the promoters of structural genes in the lignin and cellulose biosynthetic pathways. Taken together, our data show that PtoMYB74 positively regulates the secondary cell wall biosynthesis in poplar

Process design in SISO systems with input multiplicity using bifurcation analysis and optimisation

This paper presents an approach using continuation and optimisation methods for modifying a process design to avoid control difficulties caused by input multiplicity. The approach assumes an initial design, with a preassigned SISO control structure, has been obtained and is useful where there is an input multiplicity in the operating region. The condition for input multiplicity is obtained by inflating the state space model with a state representing the locus of the point of zero gain. The multiplicity condition is determined using the bifurcation analysis package, AUTO, which allows the study of the influence of operating conditions and parameters on input multiplicity behaviour to obtain an expression for the point of zero gain as a function of the design and disturbance variables. A process modification problem is formulated within an optimisation framework and solved to determine the minimal design parameter changes necessary to avoid input multiplicity given an assumed maximal disturbance. Results are presented for the application of the algorithm to a CSTR system demonstrating that small changes in some design variables can avoid input multiplicity problems in this case, and that the method can determine the changes necessary

Qwen Technical Report

Large language models (LLMs) have revolutionized the field of artificial intelligence, enabling natural language processing tasks that were previously thought to be exclusive to humans. In this work, we introduce Qwen, the first installment of our large language model series. Qwen is a comprehensive language model series that encompasses distinct models with varying parameter counts. It includes Qwen, the base pretrained language models, and Qwen-Chat, the chat models finetuned with human alignment techniques. The base language models consistently demonstrate superior performance across a multitude of downstream tasks, and the chat models, particularly those trained using Reinforcement Learning from Human Feedback (RLHF), are highly competitive. The chat models possess advanced tool-use and planning capabilities for creating agent applications, showcasing impressive performance even when compared to bigger models on complex tasks like utilizing a code interpreter. Furthermore, we have developed coding-specialized models, Code-Qwen and Code-Qwen-Chat, as well as mathematics-focused models, Math-Qwen-Chat, which are built upon base language models. These models demonstrate significantly improved performance in comparison with open-source models, and slightly fall behind the proprietary models.Comment: 59 pages, 5 figure

Disruption of Ant-Aphid Mutualism in Canopy Enhances the Abundance of Beetles on the Forest Floor

Ant-aphid mutualism is known to play a key role in the structure of the arthropod community in the tree canopy, but its possible ecological effects for the forest floor are unknown. We hypothesized that aphids in the canopy can increase the abundance of ants on the forest floor, thus intensifying the impacts of ants on other arthropods on the forest floor. We tested this hypothesis in a deciduous temperate forest in Beijing, China. We excluded the aphid-tending ants Lasius fuliginosus from the canopy using plots of varying sizes, and monitored the change in the abundance of ants and other arthropods on the forest floor in the treated and control plots. We also surveyed the abundance of ants and other arthropods on the forest floor to explore the relationships between ants and other arthropods in the field. Through a three-year experimental study, we found that the exclusion of ants from the canopy significantly decreased the abundance of ants on the forest floor, but increased the abundance of beetles, although the effect was only significant in the large ant-exclusion plot (80*60 m). The field survey showed that the abundance of both beetles and spiders was negatively related to the abundance of ants. These results suggest that aphids located in the tree canopy have indirect negative effects on beetles by enhancing the ant abundance on the forest floor. Considering that most of the beetles in our study are important predators, the ant-aphid mutualism can have further trophic cascading effects on the forest floor food web