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We studied the distribution pattern, species diversity and life-formspectra of plant communities along an altitudinal gradient in the mid-sectionofthe northern slopes of Qilianshan Mountains by means of multivariate analyses.Two data sets (167 species × 75 plots, 10 environmental variables ×75 plots), originated from the fieldworks in 1998–1999, were subjected toTWINSPAN and DCCA, resulting in 8 major plant communities: 1)Asterothamnus centraliasiaticus–Halogetonarachnoideus desert grassland on azonal substrates from 1450 to 1600m and 2) zonal Reaumuria soogorica desertgrassland on gravels from 1470 to 1900 m; 3) Stipaprzewalskii–Stipa purpurea montane grassland from 2200 to 2900m; 4) Polygonum viviparum alpine grasslandfrom 2900 to 3700 m; 5) Caraganastenophylla–Ajaniafruticulosa dry-warm shrubland from 2350 to 2800 m; 6)Sabina przewalskii mid-wet warm forest from 2700 to 3300m; 7) Picea crassifolia cold coniferousforestfrom 2450 to 3200 m; 8) Caragana jubatawet-cold alpine shrubland from 3100 to 3700 m. Species diversityand species richness of both grasslands and forests peaked at the intermediateportion of the elevational gradient. Evenness might be strongly influenced byeither biotic or abiotic factors at a local scale, while seems quiteindependentof an elevational gradient at landscape scales. Beta-diversity decreased from1500 to 3700 m, indicating that species turnover declined withincreased elevation. Both richness of life-form and total species richness in agiven altitudinal belt (gamma-diversity) peaked at intermediate elevations,while relative species richness of different life-form varied differently alongthe altitudinal gradient. 相似文献
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为阐明植物群落结构特征和物种多样性之间的相互关系,选择额尔齐斯河流域白桦林国家森林公园的天然垂枝桦(Betula pendula)纯林、垂枝桦苦杨混交林、垂枝桦白柳混交林为研究对象,分林层调查群落的基本特征参数(高度、枝下高、冠幅、胸径、盖度等),计算物种重要值、丰富度指数、多样性指数、均匀度指数,并进行典范对应分析。结果表明:(1)垂枝桦白柳混交林的乔木层树高、枝下高和灌木层的地径、盖度均最高; 3种群落的草本层特征参数(除基径)均具有显著差异;垂枝桦白柳林的盖度分别比垂枝桦苦杨林和垂枝桦纯林高19.1%和51.8%。(2)3种群落的乔木层重要值最高为垂枝桦,灌木层为疏花蔷薇(Rosa laxa)、阿尔泰山楂(Crataegus altaica),草本层为莎薹草(Carex bohemica)。(3)3种群落类型中乔木层的丰富度指数R、Simpson指数、Shannon-Wiener指数和灌木层的Pielou指数、Alatalo指数呈现出相同规律,即垂枝桦白柳混交林>垂枝桦苦杨混交林>垂枝桦纯林;草本层中除Alatalo指数之外,其他指数均呈现垂枝桦纯林>垂枝桦苦杨混交林>垂枝桦白柳混交林(P>0.05)。(4)CCA排序结果表明,不同垂枝桦林群落结构特征与物种多样性关系有差异。其中,垂枝桦纯林中,对物种多样性影响最大的是乔木枝下高、灌木株高、冠幅以及草本盖度;垂枝桦苦杨混交林中,对物种多样性影响最大的是乔木高度和冠幅、灌木冠幅和草本高度;垂枝桦白柳林中,对物种多样性影响最大的是乔木胸径、灌木冠幅、盖度以及草本高度。研究表明,乔木枝下高度、灌木冠幅、草本高度是影响3种群落类型物种多样性的主要因素。 相似文献
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Sigrid Dassen Roeland Cortois Henk Martens Mattias de Hollander George A. Kowalchuk Wim H. van der Putten Gerlinde B. De Deyn 《Molecular ecology》2017,26(15):4085-4098
Plants are known to influence belowground microbial community structure along their roots, but the impacts of plant species richness and plant functional group (FG) identity on microbial communities in the bulk soil are still not well understood. Here, we used 454‐pyrosequencing to analyse the soil microbial community composition in a long‐term biodiversity experiment at Jena, Germany. We examined responses of bacteria, fungi, archaea, and protists to plant species richness (communities varying from 1 to 60 sown species) and plant FG identity (grasses, legumes, small herbs, tall herbs) in bulk soil. We hypothesized that plant species richness and FG identity would alter microbial community composition and have a positive impact on microbial species richness. Plant species richness had a marginal positive effect on the richness of fungi, but we observed no such effect on bacteria, archaea and protists. Plant species richness also did not have a large impact on microbial community composition. Rather, abiotic soil properties partially explained the community composition of bacteria, fungi, arbuscular mycorrhizal fungi (AMF), archaea and protists. Plant FG richness did not impact microbial community composition; however, plant FG identity was more effective. Bacterial richness was highest in legume plots and lowest in small herb plots, and AMF and archaeal community composition in legume plant communities was distinct from that in communities composed of other plant FGs. We conclude that soil microbial community composition in bulk soil is influenced more by changes in plant FG composition and abiotic soil properties, than by changes in plant species richness per se. 相似文献
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Qinfeng Guo 《Molecular ecology》2012,21(22):5396-5403
The genetic variation across a species’ range is an important factor in speciation and conservation, yet searching for general patterns and underlying causes remains challenging. While the majority of comparisons between central and marginal populations have revealed a general central–marginal (C–M) decline in genetic diversity, others show no clear pattern. Similarly, most latitudinal studies (although much fewer, especially those conducted rangewide) also showed latitudinal trends in genetic variation. To date, the C–M and latitudinal patterns have often been examined independently and have rarely been considered together when accounting for the observed genetic variation across species ranges. Here, in the light of the most recent findings, I show how latitude might be responsible for some of the deviations from the general C–M trends in genetic diversity, and vice versa. In the future, integrating latitude and range geometry with climate‐induced species migration would offer important insights into conservation prioritization across species ranges. 相似文献
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Assembly of fungal communities remains poorly understood in part because of the daunting range of spatial scales that may be involved in this process. Here, we use individual leaves as a natural sampling unit, comprising spatially distinct habitat and/or resource patches with unique histories and suites of resources. Spatial patterns in fungal beta diversity were tested for consistency with the metacommunity paradigms of species sorting and neutral dynamics. Thirty senesced leaves were collected from the forest floor (O horizon) in replicate upland forest, riparian forest and vernal pool habitats. We quantified spatial distance between leaves, and fungal community composition was assayed by terminal restriction fragment length polymorphism. Significant distance‐decay relationships were detected at all but one upland site. This is the first study where changes in fungal community composition were quantified across discrete adjacent habitat patches, providing evidence that fungal distance decay is operational at a scale of centimetres. Although leaves of differing lignin contents were sampled from each site, leaf type was not consistently important in explaining variation in fungal community composition. However, depth of a leaf within the forest floor significantly influenced community composition at five of six sites. Environmental heterogeneity associated with depth could include moisture gradients, relative influence of soil or spore colonization, and impact of forest floor biotic community (i.e. collembola and earthworms). Because the influence of spatial distance and depth on fungal community composition could not be disentangled, both species‐sorting and neutral processes may be embedded within the distance‐decay relationships that we found. 相似文献
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Denny Z. H. Levett Agnese Viganò Daniele Capitanio Michele Vasso Sara De Palma Manuela Moriggi Daniel S. Martin Andrew J. Murray Paolo Cerretelli Mike P. W. Grocott Cecilia Gelfi 《Proteomics》2015,15(1):160-171
This study employed differential proteomic and immunoassay techniques to elucidate the biochemical mechanisms utilized by human muscle (vastus lateralis) in response to high altitude hypoxia exposure. Two groups of subjects, participating in a medical research expedition (A, n = 5, 19d at 5300 m altitude; B, n = 6, 66d up to 8848 m) underwent a ≈ 30% drop of muscular creatine kinase and of glycolytic enzymes abundance. Protein abundance of most enzymes of the tricarboxylic acid cycle and oxidative phosphorylation was reduced both in A and, particularly, in B. Restriction of α‐ketoglutarate toward succinyl‐CoA resulted in increased prolyl hydroxylase 2 and glutamine synthetase. Both A and B were characterized by a reduction of elongation factor 2alpha, controlling protein translation, and by an increase of heat shock cognate 71 kDa protein involved in chaperone‐mediated autophagy. Increased protein levels of catalase and biliverdin reductase occurred in A alongside a decrement of voltage‐dependent anion channels 1 and 2 and of myosin‐binding protein C, suggesting damage to the sarcomeric structures. This study suggests that during acclimatization to hypobaric hypoxia the muscle behaves as a producer of substrates activating a metabolic reprogramming able to support anaplerotically the tricarboxylic acid cycle, to control protein translation, to prevent energy expenditure and to activate chaperone‐mediated autophagy. 相似文献
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Cesc Múrria Núria Bonada Mark Vellend Carmen Zamora‐Muñoz Javier Alba‐Tercedor Carmen Elisa Sainz‐Cantero Josefina Garrido Raul Acosta Majida El Alami Jose Barquín Tomáš Derka Mario Álvarez‐Cabria Marta Sáinz‐Bariain Ana F. Filipe Alfried P. Vogler 《Molecular ecology》2017,26(21):6085-6099
Community assembly is determined by a combination of historical events and contemporary processes that are difficult to disentangle, but eco‐evolutionary mechanisms may be uncovered by the joint analysis of species and genetic diversity across multiple sites. Mountain streams across Europe harbour highly diverse macroinvertebrate communities whose composition and turnover (replacement of taxa) among sites and regions remain poorly known. We studied whole‐community biodiversity within and among six mountain regions along a latitudinal transect from Morocco to Scandinavia at three levels of taxonomic hierarchy: genus, species and haplotypes. Using DNA barcoding of four insect families (>3100 individuals, 118 species) across 62 streams, we found that measures of local and regional diversity and intraregional turnover generally declined slightly towards northern latitudes. However, at all hierarchical levels we found complete (haplotype) or high (species, genus) turnover among regions (and even among sites within regions), which counters the expectations of Pleistocene postglacial northward expansion from southern refugia. Species distributions were mostly correlated with environmental conditions, suggesting a strong role of lineage‐ or species‐specific traits in determining local and latitudinal community composition, lineage diversification and phylogenetic community structure (e.g., loss of Coleoptera, but not Ephemeroptera, at northern sites). High intraspecific genetic structure within regions, even in northernmost sites, reflects species‐specific dispersal and demographic histories and indicates postglacial migration from geographically scattered refugia, rather than from only southern areas. Overall, patterns were not strongly concordant across hierarchical levels, but consistent with the overriding influence of environmental factors determining community composition at the species and genus levels. 相似文献
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Mountains are among the most powerful natural gradients for testing ecological and evolutionary responses of biota to environmental influences because differences in climate and plant structure occur over short spatial scales. We describe the spatiotemporal distribution patterns and drives of fruit‐feeding butterfly diversity in the mountainous region of Serra do Cipó, Minas Gerais, Brazil. Seven elevations from 822 to 1,388 m a.s.l. were selected for evaluating the effects of abiotic factors and vegetation characteristics on butterfly diversity. A total of 44 fruit‐feeding butterfly species were recorded in a two‐year study. Species richness (local and regional) of fruit‐feeding butterflies decreased with increasing elevation. The interaction between temperature or humidity and precipitation influenced the abundance and β‐diversity of butterflies in the elevation gradient, whereas β‐diversity decreased with increasing plant richness. Butterfly richness (local and regional) and β‐diversity varied with the sampling period, with fewer species in July (2012 and 2013), the dry period, as expected for Neotropical insects. β‐Diversity in space and time was due to species replacement (turnover), indicating that butterfly composition differs throughout the mountain and over time. In summary, climate and plant richness largely influence butterfly diversity in the elevational gradient. Climatic changes in conjunction with increasing anthropic impacts on mountainous regions of southeast Brazil will likely influence the community of mountaintop butterflies in the Espinhaço Mountain Range. Abstract in Portuguese is available with online material. 相似文献
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Giuseppina Messina Roberto Cazzolla Gatti Angeliki Droutsa Martina Barchitta Elisa Pezzino Antonella Agodi Bianca Maria Lombardo 《Ecology and evolution》2016,6(1):191-201
Biological diversity analysis is among the most informative approaches to describe communities and regional species compositions. Soil ecosystems include large numbers of invertebrates, among which soil bugs (Crustacea, Isopoda, Oniscidea) play significant ecological roles. The aim of this study was to provide advices to optimize the sampling effort, to efficiently monitor the diversity of this taxon, to analyze its seasonal patterns of species composition, and ultimately to understand better the coexistence of so many species over a relatively small area. Terrestrial isopods were collected at the Natural Reserve “Saline di Trapani e Paceco” (Italy), using pitfall traps monthly monitored over 2 years. We analyzed parameters of α‐ and β‐diversity and calculated a number of indexes and measures to disentangle diversity patterns. We also used various approaches to analyze changes in biodiversity over time, such as distributions of species abundances and accumulation and rarefaction curves. As concerns species richness and total abundance of individuals, spring resulted the best season to monitor Isopoda, to reduce sampling efforts, and to save resources without losing information, while in both years abundances were maximum between summer and autumn. This suggests that evaluations of β‐diversity are maximized if samples are first collected during the spring and then between summer and autumn. Sampling during these coupled seasons allows to collect a number of species close to the γ‐diversity (24 species) of the area. Finally, our results show that seasonal shifts in community composition (i.e., dynamic fluctuations in species abundances during the four seasons) may minimize competitive interactions, contribute to stabilize total abundances, and allow the coexistence of phylogenetically close species within the ecosystem. 相似文献
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Timothée Poisot Elsa Canard David Mouillot Nicolas Mouquet Dominique Gravel 《Ecology letters》2012,15(12):1353-1361
In a context of global changes, and amidst the perpetual modification of community structure undergone by most natural ecosystems, it is more important than ever to understand how species interactions vary through space and time. The integration of biogeography and network theory will yield important results and further our understanding of species interactions. It has, however, been hampered so far by the difficulty to quantify variation among interaction networks. Here, we propose a general framework to study the dissimilarity of species interaction networks over time, space or environments, allowing both the use of quantitative and qualitative data. We decompose network dissimilarity into interactions and species turnover components, so that it is immediately comparable to common measures of β‐diversity. We emphasise that scaling up β‐diversity of community composition to the β‐diversity of interactions requires only a small methodological step, which we foresee will help empiricists adopt this method. We illustrate the framework with a large dataset of hosts and parasites interactions and highlight other possible usages. We discuss a research agenda towards a biogeographical theory of species interactions. 相似文献
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Ariane A. Rocha Carlos J. C. Pinto Richard I. Samuels Daniel Alexandre Carlos P. Silva 《Archives of insect biochemistry and physiology》2014,85(3):152-163
The leaffooted bug, Leptoglossus zonatus (Hemiptera: Coreidae) is an emerging pest of several crops around the World and up to now very little is known of its digestive system. In this article, glycoside hydrolase (carbohydrase) activities in the adult midgut cells and in the luminal contents of L. zonatus adult females were studied. The results showed the distribution of digestive carbohydrases in adults of this heteropteran species in the different intestinal compartments. Determination of the spatial distribution of α‐glucosidase activity in L. zonatus midgut showed only one major molecular form, which was not equally distributed between soluble and membrane‐bound isoforms, being more abundant as a membrane‐bound enzyme. The majority of digestive carbohydrases were found in the soluble fractions. Activities against starch, maltose and the synthetic substrate NPαGlu were found to show the highest levels of activity, followed by enzymes active against galactosyl oligosaccharides. Based on ion‐exchange chromatography elution profiles and banding patterns in mildly denaturing electrophoresis, both midgut α‐amylases and α‐galactosidases showed at least two isoforms. The data suggested that the majority of carbohydrases involved in initial digestion were present in the midgut lumen, whereas final digestion of starch and of galactosyl oligosaccharides takes place partially within the lumen and partially at the cell surface. The complex of carbohydrases here described was qualitatively appropriate for the digestion of free oligosaccharides and oligomaltodextrins released by α‐amylases acting on maize seed starch granules. 相似文献
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Questions: Do ordination patterns differ when based on vegetation samples recorded in plots of different size? If so, how large is the effect of plot size relative to the effects of data set heterogeneity and of using presence/absence or cover‐abundance data? Can we combine plots of different size in a single ordination? Methods: Two homogeneous and two heterogeneous data sets were sampled in Czech forests and grasslands. Cover‐abundances of plant species were recorded in series of five or six nested quadrats of increasing size (forest 49‐961 m2; grassland 1‐49 m2). Separate ordinations were computed for plots of each size for each data set, using either species presences/absences or cover‐abundances recorded on an ordinal scale. Ordination patterns were compared with Procrustean analysis. Also, ordinations of data sets jointly containing plots of different size were calculated; effects of plot size were evaluated using a Monte Carlo test in constrained ordination. Results: The results were consistent between forest and grassland data sets. In homogeneous data sets, the effect of presence/absence vs. cover‐abundance was similar to, or larger than, the effect of plot size; for presence/absence data the differences between ordinations of differently sized plots were smaller than for cover‐abundance data. In heterogeneous data sets, the effect of plot size was larger than the effect of presence‐absence vs. cover‐abundance. The plots of smaller size (= 100 m2 in forests, = 4 m2 in grasslands) yielded the most deviating ordination patterns. Joint ordinations of differently sized plots mostly did not yield patterns that would be artifacts of different plot size, except for plots from the homogeneous data sets that differed in size by a factor of four or higher. Conclusions: Variation in plot size does influence ordination patterns. Smaller plots tend to produce less stable ordination patterns, especially in data sets with low ß‐diversity and species cover‐abundances. Data sets containing samples from plots of different sizes can be used for ordination if they represent vegetation with large ß‐diversity. However, if data sets are homogeneous, i.e. with low ß‐diversity, the differences in plot sizes should not be very large, in order to avoid the danger of plot size differences distorting the real vegetation differentiation in ordination patterns. 相似文献
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FRANCISCA FUENTES‐RODRÍGUEZ MELCHOR JUAN IRENE GALLEGO MIRIAN LUSI ENCARNACIÓN FENOY DAVID LEÓN PATRICIO PEÑALVER JULIA TOJA J. JESÚS CASAS 《Freshwater Biology》2013,58(1):63-78
1. Agricultural intensification has caused dramatic biodiversity loss in many agricultural landscapes over the last century. Here, we investigated whether new types of farm ponds (made of artificial substrata) in intensive systems and natural‐substratum ponds in traditional farming systems differ in their value for aquatic biodiversity conservation. 2. We analysed the main patterns of environmental variation, compared α‐, β‐ and γ‐diversity of macroinvertebrates between ponds types and evaluated the role of submerged aquatic vegetation (SAV). Generalised additive models (GAM) were used to analyse the relationships of α‐ and β‐diversity with environmental predictors, and variation partitioning to separate the effect of environmental and spatial characteristics on the variation in macroinvertebrate assemblages. Moran’s eigenvector maps (MEMs) were used to define spatial variables. 3. A principal coordinate analysis (PCoA) detected a primary environmental gradient that separated nutrient‐rich ponds from those dominated by SAV; a secondary morphometric gradient distinguished natural‐substratum ponds, with large surface area and structural complexity, from artificial‐substratum ponds with steeper slopes. Natural‐substratum ponds had almost twice the α‐ and γ‐diversity of artificial‐substratum ponds, and diversity significantly increased when SAV was present, particularly in artificial‐substratum ponds. Total phosphorus (TP) strongly contributed to explain the patterns in diversity, while SAV was a significant predictor of assemblage composition and diversity. GAMs revealed optima of both α‐diversity at intermediate SAV covers and β‐diversity at intermediate–high TP concentrations. 4. These findings have important implications for conservation planning. Adaptation of artificial‐substratum ponds by adding natural substratum and smoothing the gradient of pond margins would improve their conservation value. Development of SAV with occasional harvests and certain cautionary measures to control nutrient levels may also improve both the agronomical and environmental function of ponds. 相似文献
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The NMR and molecular dynamics methods are used to study the conformations of a hexapeptide, GRGDTP, which has been shown to be accessible to various types of cell‐adhesion based cellular behaviors such as cell‐to‐matrix interactions, cell differentiation, immunogenicity development, gene expression, angiogenesis, metastasis, sex determination and gamete fusion. 1H‐NMR results indicate the existence of weak 5→2 hydrogen bonded β‐turn type‐III. Molecular simulation studies using a mixed protocol of distance geometry, constrained minimization, restrained molecular dynamics followed by energy minimization resulted additional conformations that include about 64% of population of inverse γ‐turn (HB, 3→1) and about 35% population of γ‐turn (HB, 4→2). The inter‐proton distances observed in γ‐and inverse γ‐turns are also consistent with the NMR constraints. The variable internal hydrogen bonding due to γ‐turns initiated at Gly 1 and Arg 2 , and its tendency to inter‐convert between γ‐and inverse γ‐turn conformations imply that the peptide is flexible in nature. © 2013 Wiley Periodicals, Inc. Biopolymers 99: 460–471, 2013. 相似文献
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David Anthony Kirk Marie‐Hlne Brice Michael S. Bradstreet Ken A. Elliott 《Ecology and evolution》2021,11(1):58-88
Invasion by generalist tree species can cause biotic homogenization, and such community impoverishment is likely more important in rare forest types. We quantified changes in tree diversity within Carolinian (range in Central Hardwood Forest), central (range in Central Hardwood Forest and Northern Hardwood‐Conifer Forest), and northern species [range reached Northern‐Conifer‐Hardwood/closed Boreal (spruce‐Fir) Forest] in an old forest tract in southern Canada at points surveyed 24 years apart. We asked: How did mature tree and sapling composition and abundance change for the three species’ groups? Did those changes lead to biotic homogenization? Can species’ changes be explained by community traits? We tested for differences in temporal and spatial tree β‐diversity, as well as forest composition and structure, using univariate/multivariate analyses and a community trait‐based approach to identify drivers of change. Major increases occurred in abundance for mature Acer rubrum (northern), while other species decreased (Fraxinus americana, Populus grandidentata); declines were found in A. saccharinum (central) and Cornus florida (Carolinian). Species composition of saplings, but not mature trees, changed due to replacement; no evidence for biotic homogenization existed in either cohort. As a group, northern mature tree species increased significantly, while central species decreased; saplings of pooled Carolinian species also declined. Shade tolerance in mature trees increased, reflecting successional changes, while drought tolerance decreased, perhaps due to changing temperatures, altered precipitation or ground water levels. Saplings showed declines in all traits, probably because of compositional change. Our results demonstrated that saplings can more closely reflect change in forest dynamics than mature trees, especially over short time periods. Based on sapling trends, this remnant could ultimately transition to a mesophytic hardwood stand dominated by A. rubrum and other shade‐tolerant species, creating a more homogeneous forest. While encouraging regeneration for Carolinian and central tree species could ensure high levels of diversity are conserved in the future, it is important to balance this with the primary management goal of maintaining the forest''s old‐growth characteristics. 相似文献