18 research outputs found

    Comparative genomics reveals insights into avian genome evolution and adaptation

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    Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific erosion of repetitive elements, large segmental deletions, and gene loss. Avian genomes furthermore show a remarkably high degree of evolutionary stasis at the levels of nucleotide sequence, gene synteny, and chromosomal structure. Despite this pattern of conservation, we detected many non-neutral evolutionary changes in protein-coding genes and noncoding regions. These analyses reveal that pan-avian genomic diversity covaries with adaptations to different lifestyles and convergent evolution of traits

    Coupling Mechanism of the Tourism Industrial Network Based on Circular Economy

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    This paper summarizes the research situation of circular economy and tourism industrial network at home and abroad, introduces the concept and characteristics of tourism industrial network, and analyzes the coupling mechanism of tourism industrial network based on circular economy

    Coupling Mechanism of the Tourism Industrial Network Based on Circular Economy

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    This paper summarizes the research situation of circular economy and tourism industrial network at home and abroad, introduces the concept and characteristics of tourism industrial network, and analyzes the coupling mechanism of tourism industrial network based on circular economy.Circular economy, Tourism industrial network, Coupling mechanism, Resource /Energy Economics and Policy,

    Molecular evidence for Pleistocene refugia at the eastern edge of the Tibetan Plateau

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    The role of the Quaternary ice ages in forming the contemporary genetic structure of populations has been well studied in a number of global regions. However, due to the different nature of glaciations and complex topography, their role in shaping eastern Eurasian genetic diversity, particular in areas surrounding the Tibetan Plateau have remained largely unstudied. We aimed to address this question by examining the genetic structure of an alpine forest-associated taxon, the blood pheasant (Ithaginis cruentus) to infer its phylogeographic history. We detected three phylogenetic lineages and four current population groups. By comparing molecular and palaeovegetation data, we found that major glaciations during the Pleistocene have had a major impact upon the current genetic diversity of this species. Coalescent simulations indicate that the populations retreated to different refugia during some glacial periods in the Pleistocene, but persisted through the last glacial maximum (LGM). The most significant recent population expansion was found to have occurred before the LGM, during which palaeoclimatic data indicate that the climate was both warmer and wetter than today. In contrast, during the LGM populations may have adopted an altitudinal shift strategy in order to track changes in alpine glaciers, exemplifying a general response for montane species in the region where alpine glaciations were not large enough to cause qualitative changes in vegetation. Although analysis based on a plumage related gene showed that divergent selection may have contributed to current patterns of intra-specific diversity, demographic isolation is inferred to have played a more dominant role

    Have Agricultural Land-Use Carbon Emissions in China Peaked? An Analysis Based on Decoupling Theory and Spatial EKC Model

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    Assessing the emission-peaking process of agricultural land use provides valuable insights for mitigating global warming. This study calculated agricultural land-use carbon emissions (ALUCEs) in China from 2000 to 2020 and explored the peaking process based on quantitative criteria. Further, we applied the Tapio decoupling index and environmental Kuznets curve (EKC) model to discuss the robustness of the peaking process. The main conclusions are as follows: (1) From 2000 to 2020, China’s average ALUCEs were 368.1 Mt C-eq (1349.7 CO2-eq), peaking at 396.9 Mt C-eq (1455.3 Mt CO2-eq) in 2015 before plateauing. Emissions from agricultural materials and soil management had entered the declining period, while those from rice cultivation were in the peaking period, those from straw burning were still rising, and those from livestock breeding remained at the plateauing phase. (2) The provinces of Beijing, Tianjin, and nine others saw a decline in ALUCEs, while Hainan, Guizhou, and another nine provinces observed plateauing, and Ningxia, Qinghai, and six other provinces experienced peaking. (3) Decoupling analysis confirmed that emission-peaking states remained stable even with agricultural growth. Instead of an inverted U-shaped relationship, we found an N-shaped relationship between ALUCEs and agricultural GDP. The spatial EKC model indicated that the peaking process had spillover effects between provinces. It is recommended that China accelerate ALUCE mitigation based on the source and phase of emissions, considering the peaking process and magnitude

    A new method for quantifying genotyping errors for noninvasive genetic studies

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    More and more noninvasive genetic data are being produced but a general methodology to quantify genotyping error rates from non-pilot data remains lacking. Here we propose a mathematical approach to estimate genotyping error rates by exploring the relationship between errors and PCR replicates. This method can be used to quantify the error rates for either the multi-tubes approach designed by Taberlet et al. (Nucleic Acids Res 24: 3189–3194, 1996) or the pilot method by Prugh et al. (Mol Ecol 14: 1585–1596, 2005)

    Modeling Progressive Damage and Failure of Single-Lap Thin-Ply-Laminated Composite-Bolted Joint Using LaRC Failure Criterion

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    Thin-ply composite failure modes also significantly differ from conventional ply composite failure modes, with the final failure mechanism switching from irregular progressive failure to direct fracture characterized by a uniform fracture with the reduction of the ply thickness. When open holes and bolt joints are involved, thin-ply-laminated composites exhibit more complex stress states, damage evolution, and failure modes. Compared to the experimental study of thin-ply-laminated composite-bolted joints, there are few reports about numerical analysis. In order to understand the damage evolution and failure mechanism of thin-ply-laminated composites jointed by single-lap bolt, a progressive damage model based on three-dimensional (3D) LaRC failure criterion combined with cohesive element is constructed. Through an energy-based damage evolution method, this model can capture some significant mechanical characteristics in thin-ply-laminated structures, such as the in situ effect, delamination inhibition, and fiber compressive kinking failure. The comparisons between the numerical predictions and experimental observations are made to verify the accuracy of the proposed model. It is found that the predicted stress-displacement curves, failure modes, damage morphologies, etc., are consistent with the experimental results, indicating that the presented progressive damage analysis method displays excellent accuracy. The predicted stress at the onset of delamination is 50% higher than that of the conventional thick materials, which is also consistent with experimental results. Moreover, the numerical model provides evidence that the microstructure of thin-ply-laminated composite performs better in uniformity, which is more conducive to inhibiting the intra-layer damage and the expansion of delamination damage between layers. This study on the damage inhibition mechanism of thin-ply provides a potential analytical tool for evaluating damage tolerance and bearing capabilities in thin-ply-laminated composite-bolted joints
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