Reduced Species Diversity Research Articles

Improved feeding tolerance and growth linked to gut microbial diversity in very-low-birthweight infants fed with mother's own milk vs donor milk.

Early infant nutrition plays a crucial role in shaping future health,1 and human milk is the first choice for all infants. It has numerous benefits, including improved neurological, immunological or metabolic outcomes, and makes a significant contribution to early intestinal microbiome development.2-4 Mother's own milk is even more important for preterm infants, as they frequently have a different gut microbiota to term infants, with reduced species diversity. This makes them more vulnerable to serious intestinal inflammatory conditions like necrotising enterocolitis.5, 6 Numerous studies have demonstrated the benefits of feeding human milk, rather than formula, in intensive care units, but there has been a lack of studies comparing maternal and donor milk.7, 8 The Ford et al study was the first to compare the development of intestinal microbiota and clinical outcomes in infants with an exclusive human milk diet of mother's own milk or donor milk. They enrolled 125 infants born weighing less than 1500 g, without barriers for enteral feeding, and grouped them based on which milk accounted for more than 50% of their diet. Their results highlight several points. First, infants fed mother's own milk or donor milk had significantly different microbiota at the phylum and genius level by four and six weeks of life. Those fed with mother's own milk had increased microbial diversity and an abundance of beneficial bacteria, such as Bifidobacterium (P = .02) and Bacteroides (P = .04) that protect against severe morbidities. Second, they were 60% less likely to experience feeding intolerance than those who received donor milk, leading to improved growth parameters. This was consistent with previous studies that suggested possible explanations, such as lower protein content in donor milk or diminished lipase activity due to pasteurisation.3, 9 Third, mother's own milk consistently protected the gut microbiota from the effect of antibiotics, which may have important clinical implications. The study strengths were the large sample size, longitudinal design and multiple microbiota assessments, while the limitations were its observational design and the inability to account for confounding variables and other potential sources of bias. The study adds additional data to the benefits of mother's own milk for very-low-birthweight infants and further supports efforts to improve lactation in neonatal care units and maintain the mother's milk supply during extended hospital stays. However, further research is needed on the beneficial effects of probiotics, adjusted by feeding type, on microbiological and clinical outcomes. It is plausible that nutrition and probiotic supplementation may act together in the preterm infant's gut, leading to a global improvement in neonatal health. https://ebneo.org/2019/10/gut-microbial-diversity/ The authors declare no conflict of interest.

Comparison of Flora of Small-Scale Mined and Unmined-Sites in Dunkwa-East Municipality, Ghana

The impacts of small-scale mining on the vegetal cover as well the livelihoods of communities in mined areas in developing countries such as Ghana are far-reaching. This study assessed the impacts of small-scale mining on flora of conservation and economic significance through quantification of species richness, and species diversity. Mined and unmined sites were chosen in the Dunkwa East Municipality of Ghana. Five belt transects each (200m × 200m) were constructed in both sites. Each belt transect was divided into 100 quadrats (20m × 20m) and plant species in each of the quadrat were identified in the field and or the herbarium of the School of Biological Sciences, University of Cape Coast. One hundred and fifty seven species distributed in 140 genera and 54 families were identified in the mined area whilst the 209 species identified in the unmined area were in 185 genera and 73 families. Plant families Euphorbiaceae, Rubiaceae and Asteraceae were more diverse whilst Asteraceae, Poaceae and Euphorbiaceae were dominant in the unmined area. In the mined area, however, Poaceae, Euphorbiaceae and Asteraceae were more diverse. Pteridium aquilinum, Tridax procumbens and Waltheria indica in the unmined area and Chromolaena odorata, Sporobolus pyramidalis and Euphorbia hirta in the mined area were the dominant species. Small-scale miming activities have caused reduction in species diversity, richness and economic and commercial values in the area. Higher disturbance of the flora has resulted in more secondary species in the mined area. Restoration is required in the study area.

Integrated effect of fertilizer application and protective measures on weed infestation and potato yield

The results of the research have revealed integrated effect of the mineral fertilizer application and protective measures influence on weed infestation and potato yield. This effect was developed on the second half of the vegetation and expressed in more stronger inhibition of plant development (from 36,6 to 20,4 and 11,1 g/m2 on low, medium and high levels of mineral nutrition, respectively), in the reduction of species diversity (from 12 to 10 and 10 species/m2) and number of weeds (from 69 to 42 and 32 species/m2). The highest biological (biomass reduction – 95,3%, the number of weeds – 79%) and economic (yield increase – 228 с/ha or 107%) effect was achieved by the high rates of mineral fertilizer application and combined protective measures of potato crops from weeds. This variant was characterized by the greatest profitability (125,3%), whereas chemical protection providing double treatment of potato plantings with herbicides, even at the middle and high level of mineral nutrition, was less effective (102,6 and 109%) in economic terms.

Vegetation Dynamics and Diversity Status in Mughal Garden Wah, Pakistan

Classification and ordination of vegetation of Mughal Garden, Wah, Pakistan was done along with assessment of diversity status. A total of 45 species were recorded in vegetation survey belonging to 24 families with Asteraceae and Poaceae being the largest families. Herbs dominated the flora of Wah Garden by 44.4%, shrubs 15.5%, trees 13.3%, grasses 11.1%, creeping herbs 11.1%, ferns 2.2% and aquatic herbs 2.2%. About 35.5% species were annuals, 28.8% perennials, 13.3% annuals or perennials, 8.8% annuals or biennials, 8.8% deciduous, 2.2% coniferous and evergreen species. In case of life form of species, Therophytes and Megaphanerophytes were the most prevalent among species indirect ordination techniques TWINSPAN and DCA were employed that produced two major groups which were further divided into five communities and three major groups, respectively. Shannon-Wiener diversity index, Simpson Index of diversity and Hill’s N1 and N2 diversity numbers were calculated and verified by data attribute plot through DCA suggesting reduced species diversity as Shannon-Wiener diversity index ranged between 0 and 1.67 due to increased anthropogenic activity. The outcome of this research will be useful in providing information on identification of species that are present, their distribution patterns, and classification which would help in management and conservation of native vegetation in future.

Arrested development? Investigating the role of bamboo in Araucaria Forest succession in Southern Brazil

Abstract Aims Assessing the role of a dominant native bamboo species on tree species diversity and structure in the medium term. Methods Over a 7-year period, we studied the natural regeneration of two dominant forest types in Southern Brazil (Araucaria Forest or AF; Bamboo Forest or BF) after a bamboo (Merostachys skvortzovii Send.) die-off between 2004 and 2006. The study was carried out in the Embrapa Research Station in Caçador, Santa Catarina State, Brazil. Important Findings The die-off provided ideal conditions for the establishment of several species and it kickstarted forest succession dynamics, which in turn affected regeneration diversity. Tree species richness was relatively stable with a transitory increase between 2007 and 2014 in both AF and BF. However, species richness rose in BF because of a relative increase in abundance of some species (especially late and secondary species) while a plunge in some pioneer species drove an increase in diversity. Overall, we found that BF has a lower diversity of recruits and that density declined over time, while AF is more diverse, with a more stable density. In BF, the bamboo die-off created optimal conditions for initial regeneration development (mainly fast-growing pioneer trees), which quickly transited to higher size classes. Yet, after this initial stage of pioneer recruitment, the number of recruits dropped followed by a virtual absence of growth regardless of the species group as a result of a quick bamboo reestablishment. As bamboo recreated a dense understory it reduced species diversity to original levels, suggesting a self-maintaining cycle that halts forest succession. On the other hand, the bamboo die-off had little impact on AF where a slow recruitment process typical of old-growth forests was observed. The results indicate that the die-off event had a temporary effect on species diversity i.e. restricted to forests where bamboos are dominant in a similar process described in other southern South American forests. As the first study to observe the medium-term forest dynamics related to bamboo die-off, we can conclude that when being dominant, native bamboos can hinder forest regeneration, maintaining lower levels of diversity and arresting forest succession that lasts well beyond the short-term, post-die-off effects. Many forest fragments in the region are dominated by bamboos, thus their potential for conservation is at risk and requires appropriate management.

Implications of non-native species for mutualistic network resistance and resilience.

Resilience theory aims to understand and predict ecosystem state changes resulting from disturbances. Non-native species are ubiquitous in ecological communities and integrated into many described ecological interaction networks, including mutualisms. By altering the fitness landscape and rewiring species interactions, such network invasion may carry important implications for ecosystem resistance and resilience under continued environmental change. Here, I hypothesize that the tendency of established non-native species to be generalists may make them more likely than natives to occupy central network roles and may link them to the resistance and resilience of the overall network. I use a quantitative research synthesis of 58 empirical pollination and seed dispersal networks, along with extinction simulations, to examine the roles of known non-natives in networks. I show that non-native species in networks enhance network redundancy and may thereby bolster the ecological resistance or functional persistence of ecosystems in the face of disturbance. At the same time, non-natives are unlikely to partner with specialist natives, thus failing to support the resilience of native species assemblages. Non-natives significantly exceed natives in network centrality, normalized degree, and Pollination Service Index. Networks containing non-natives exhibit lower connectance, more links on average, and higher generality and vulnerability than networks lacking non-natives. As environmental change progresses, specialists are particularly likely to be impacted, reducing species diversity in many communities and network types. This work implies that functional diversity may be retained but taxonomic diversity decline as non-native species become established in networks worldwide.

Analysis of gut microbiota and the effect of lauric acid against necrotic enteritis in Clostridium perfringens and Eimeria side-by-side challenge model.

Gut microbiota has been demonstrated to be involved in intestinal nutrition, defense, and immunity, as well as participating in disease progression. This study was to investigate gut microbiota changes in chickens challenged with netB-positive Clostridium perfringens strain (CP1) and/or the predisposing Eimeria species (Eimeria) and fed diets with fishmeal supplementation. In addition, the effects of lauric acid, a medium-chain fatty acid (MCFA), on necrotic enteritis (NE) reduction and modulation of microbiota were evaluated. The results demonstrated that microbial communities in the jejunum were distinct from those in the cecum, and the microbial community change was more significant in jejunum. Challenge of CP1 in conjunction with Eimeria significantly reduced species diversity in jejunal microbiota, but cecal microbiota remained stable. In the jejunum, CP1 challenge increased the abundance of the genera of Clostridium sensu stricto 1, Escherichia Shigella, and Weissella, but significantly decreased the population of Lactobacillus. Eimeria infection on its own was unable to promote NE, demonstrating decrements of Clostridium sensu stricto 1 and Lactobacillus. Co-infection with CP1 and Eimeria reproduced the majority of NE lesions with significant increment of Clostridium sensu stricto 1 and reduction in Lactobacillus. The advance of changes on these two taxa increased the severity of NE lesions. Further analyses of metagenomeSeq, STAMP, and LEfSe consistently showed significant overgrowth of Clostridium sensu stricto 1 was associated with NE. The supplementation of lauric acid did not reduce NE incidence and severity but decreased the relative abundance of Escherichia Shigella. In conclusion, significant overgrowth of C. perfringens as well as other Clostridium species in Clostridium sensu stricto 1 with the decrement of Lactobacillus in the jejunum is the featured microbiota correlated with NE. Controlling proliferation of Clostridium sensu stricto 1 and manipulation of Lactobacillus in the jejunum should be the strategy to prevent NE.

Impact of Land Use Changes on Soil and Vegetation Characteristics in Fereydan, Iran

To understand and manage ecosystem complexity, it is important to determine the relationships between soil characteristics, human activities, and biodiversity. This study analyzes the relationships between vegetation, soil, and man-made damage with regards to land use change in the Fereydan region, Iran. Soil physical properties such as sand and silt content, clay, saturated soil’s moisture content, and gravel percentage as well as chemical properties such as lime content, pH, electro conductivity (EC), and organic matter content were measured. In order to trace these variables, the principle component analysis (PCA) was applied. The study area was divided into three states of conditions; i.e., good condition rangelands, poor condition rangelands, and abandoned rain-fed area. Based on the results there was a significant difference between species diversity in good condition rangelands compared with two other sites. The results further revealed that among soil chemical and physical characteristics, only soil organic matter had a significant difference between different rangeland sites. According to the results, the rangelands with good conditions had the highest amount of organic matter (1.43–1.50%) compared with two other studied rangelands (poor conditions: 1.02–1.09%; abandoned rain-fed: 1.2–1.46%). The most influential factor on the species diversity index was the distance to village parameter that revealed the important role of humans in degrading rangelands and reducing species diversity.

The intestinal environment as an evolutionary adaptation to mouthbrooding in the Astatotilapia burtoni cichlid

Many of the various parental care strategies displayed by animals are accompanied by a significant reduction in food intake that imposes a substantial energy trade-off. Mouthbrooding, as seen in several species of fish in which the parent holds the developing eggs and fry in the buccal cavity, represents an extreme example of reduced food intake during parental investment and is accompanied by a range of physiological adaptations. In this study we use 16S sequencing to characterize the gut microbiota of female Astatotilapia burtoni cichlid fish throughout the obligatory phase of self-induced starvation during the brooding cycle in comparison to stage-matched females that have been denied food for the same duration. In addition to a reduction of gut epithelial turnover, we find a dramatic reduction in species diversity in brooding stages that recovers upon release of fry and refeeding that is not seen in females that are simply starved. Based on overall species diversity as well as differential abundance of specific bacterial taxa, we suggest that rather than reflecting a simple deprivation of caloric intake, the gut microbiota is more strongly influenced by physiological changes specific to mouthbrooding including the reduced epithelial turnover and possible production of antimicrobial agents.

Genomic insights into the vulnerability of sympatric whitefish species flocks.

The erosion of habitat heterogeneity can reduce species diversity directly but can also lead to the loss of distinctiveness of sympatric species through speciation reversal. We know little about changes in genomic differentiation during the early stages of these processes, which can be mediated by anthropogenic perturbation. Here, we analyse three sympatric whitefish species (Coregonus spp) sampled across two neighbouring and connected Swiss pre-alpine lakes, which have been differentially affected by anthropogenic eutrophication. Our data set comprises 16,173loci genotyped across 138 whitefish using restriction-site associated DNA sequencing (RADseq). Our analysis suggests that in each of the two lakes, the population of a different, but ecologically similar, whitefish species declined following a recent period of eutrophication. Genomic signatures consistent with hybridization are more pronounced in the more severely impacted lake. Comparisons between sympatric pairs of whitefish species with contrasting ecology, where one is shallow benthic and the other one more profundal pelagic, reveal genomic differentiation that is largely correlated along the genome, while differentiation is uncorrelated between pairs of allopatric provenance with similar ecology. We identify four genomic loci that provide evidence of parallel divergent adaptation between the shallow benthic species and the two different more profundal species. Functional annotations available for two of those loci are consistent with divergent ecological adaptation. Our genomic analysis indicates the action of divergent natural selection between sympatric whitefish species in pre-alpine lakes and reveals the vulnerability of these species to anthropogenic alterations of the environment and associated adaptive landscape.

Growth of Toxic Cyanobacteria Dolichospermum flos-aquae (Anabaena flos-aquae) in the Waters of the Boreal Zone

The life cycle of cyanobacteria Dolichospermum flos-aquae causing the blooming of waters of the boreal zone is studied. The mass propagation of the D. flos-aquae in the plankton stage occurs due to their ability to realize high biotic potential, defined by the combination of features developed during evolution, which the other partners of the plankton community lack. These include: adaptation to a certain growth temperature; low demand for nutrients; nitrogen fixation and intracellular accumulation of phosphates; and the ability of trichomes to migrate, allowing them to occupy the optimal parts of the euphotic zone for photosynthesis. It is established that the trichomes of D. flos-aquae consist of heterocysts and vegetative cells of different maturity, generosity, and activity during the planktonic stage, and their ratio changes throughout the life cycle of microorganisms. It is believed that the primary and secondary metabolites released by D. flos-aquae into the medium take part in the regulation of their own population growth, including cell destruction at the final stage of blooming, akinetes formation, and the simultaneous suppression in propagation of community partners. With the dominance of one species, the released toxic metabolites increase in years with an anticyclone type of weather, resulting in the reduction of species diversity and the simplification of the biotic community structure.

基于标准化降水蒸散指数的呼伦贝尔草原干旱变化特征及趋势分析

PDF HTML阅读 XML下载 导出引用 引用提醒 基于标准化降水蒸散指数的呼伦贝尔草原干旱变化特征及趋势分析 DOI: 10.5846/stxb201807061481 作者: 作者单位: 北京师范大学地理科学学部,北京师范大学,北京师范大学地理科学学部,北京师范大学地理科学学部 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划（2016YFC0500608-3） SPEI-based analysis of drought characteristics and trends in Hulun Buir grassland Author: Affiliation: Faculty of Geographical Science,Beijing Normal University,Beijing Normal University,Faculty of Geographical Science,Beijing Normal University,Faculty of Geographical Science,Beijing Normal University Fund Project: National Key R&D Program of China 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:呼伦贝尔草原是我国北方地区重要的防风固沙和水源涵养生态功能区，在气候变化的背景下，该区的草原畜牧业和旱作农业深受干旱的影响。研究该区干旱发生的特征及趋势，对当地采取适应气候变化对策具有重要意义。基于1960-2017年呼伦贝尔草原4个气象站逐月降水和气温资料，计算标准化降水蒸散指数（SPEI），并采用Mann-Kendall突变检验、Morlet小波分析和R/S分析法分析了近58年呼伦贝尔草原年、季尺度的气候变化及干旱特征与趋势，并结合该区实际发生的灾害事件对SPEI指数进行了验证。结果表明：1）近58年来呼伦贝尔草原在气温显著上升，降水量减少的背景下干旱化趋势显著。2）该区域年尺度和季节尺度下干旱化特征具有差异性，其中，年尺度下，该区域SPEI指数以-0.218×10 a-1倾向率呈显著下降趋势，1998年是干旱加剧的突变年，未来在11年尺度上有持续偏旱的趋势；季节尺度下，冬季SPEI指数显著增加，且未来在17年尺度上有持续偏湿的趋势，春、夏和秋季的SPEI指数均呈下降趋势，并分别在22年、9年和15年尺度上有持续偏旱的趋势。3）2000年以来，干旱发生的总频率尤其重旱和极旱的发生频率均显著高于其他年代；4）夏季和秋季分别是发生重旱和极旱次数最多的季节。5） SPEI指数在呼伦贝尔草原区的干旱监测与分析中具有较好的适用性。 Abstract:With increases in global warming intensity, the frequency and duration of droughts are showing a clear upward trend, and the global terrestrial extreme drought area is expanding, particularly on the Eurasian and African continents. Hulun Buir grassland is an important wind-fixing and water-reserving ecological functioning area in northern China. However, due to the superimposition of climate change effects, such as the frequency of drought, and human activities, the grasslands have gradually degraded to a simpler community structure with reduced species diversity, intensified desertification, and increased pests and diseases. Based on monthly precipitation and temperature data from four meteorological stations in the Hulun Buir grassland from 1960 to 2017, the standardized precipitation evapotranspiration index (SPEI) was calculated. The Mann-Kendall mutation test, Morlet wavelet analysis, and R/S analysis were used to analyze the drought change characteristics and trends on both annual and seasonal scales in the Hulun Buir grassland over the past 58 years, and the SPEI index was verified by the actual disaster events in the area. The results show that:1) between 1960 and 2017, the temperature of the Hulun Buir grassland increased gradually at a significance level of 0.05, while precipitation showed a slight decrease. In addition, the seasonal variations in temperature and precipitation are different. Among them, summer precipitation is gradually decreasing, while the other seasons are increasing at different rates. In addition to winter temperatures, the interannual temperature changes in other seasons showed an upward trend at a significance level of 0.05. Among them, the spring temperature rose at the fastest rate, reaching 0.46℃×10 a-1, followed by summer (0.39℃×10 a-1). 2) On the annual scale, the SPEI index of this region showed a downward trend with a tendency of -0.218×10a-1 (P < 0.01). 1998 is the year of drought intensified in the region, and there is a trend of persistent drought on the 11 a scale for the future; On the seasonal scale, the winter SPEI index increased significantly, and there is a trend of continuous wetness on the 17 a scale for the future. However, the SPEI index in spring, summer, and autumn showed a downward trend, and there was a trend of persistent drought on the 22 a, 9 a and 15 a scales, respectively; 3) The frequency of moderate drought occurrences is the highest among different years and seasons, and that of extreme drought is the lowest. At the beginning of the 21st century, the frequency of drought, especially severe drought and extreme drought, was significantly higher than for the past four decades. 4) Summer and autumn were the seasons with the most frequent occurrences of severe and extreme droughts, respectively. 5) The SPEI index can well characterize the drought characteristics of the Hulun Buir grassland. 参考文献 相似文献 引证文献

Habitat fragmentation, biodiversity loss and the risk of novel infectious disease emergence.

The number of microbes on Earth may be 1030, exceeding all other diversity. A small number of these can infect people and cause disease. The diversity of parasitic organisms likely correlates with the hosts they live in and the number mammal hosts for zoonotic infections increases with species richness among mammalian orders. Thus, while habitat loss and fragmentation may reduce species diversity, the habitat encroachment by people into species-rich areas may increase the exposure of people to novel infectious agents from wildlife. Here, we present a theoretical framework that exploits the species-area relationship to link the exposure of people to novel infections with habitat biodiversity. We model changes in human exposure to microbes through defined classes of habitat fragmentation and predict that increased habitat division intrinsically increases the hazard from microbes for all modelled biological systems. We apply our model to African tropical forests as an example. Our results suggest that it is possible to identify high-risk areas for the mitigation and surveillance of novel disease emergence and that mitigation measures may reduce this risk while conserving biodiversity.

Loss of only the smallest patches will reduce species diversity in most discrete habitat networks.

Under many global-change scenarios, small habitat patches are the most vulnerable to destruction. For example, smaller ponds are at greater risk in a drying climate and their loss would remove any obligate aquatic individuals present. We asked what proportional loss of species diversity from metacommunities comprised of discrete habitat patches should be expected from attrition (complete loss) of only the smallest patches under such a premise. We analyzed 175 published datasets for different taxonomic groups (vertebrates, invertebrates, and plants) and habitat types (islands, habitat islands, and fragments). We simulated the destruction of only the smallest patches to an approximate 20% of total area (range: 15.2%-24.2%) and analyzed species loss. Mean [±95% CI] species loss was 12.7% [10.8, 14.6], although 18.3% of datasets lost no species. Four broad patterns of species loss were evident, reflecting underlying differences in minimum area requirements and the degree of species turnover among patches. Regression modeling showed species loss increased with greater species turnover among patches (βSIM ) and decreased with greater area scaling of diversity (i.e., larger power-law island species-area relationship exponents). Losses also increased with greater numbers of single-patch endemics and with increasing proportions of patches destroyed. After accounting for these predictors, neither taxonomic group nor habitat type increased explained variation in species loss. Attrition of the smallest patches removed species in >80% of metacommunities, despite all larger patches and >75% of total area remaining intact. At both 10% and 20% area reduction, median species loss across all datasets was around 50% higher than predicted from methods based on the species-area relationship. We conclude that any mechanism of global change that selectively destroys small habitat patches will lead to imminent extinctions in most discrete metacommunities.

Sequential fishways reconnect a coastal river reflecting restored migratory pathways for an entire fish community

River regulation infrastructure has been implicated in worldwide aquatic biodiversity loss. In‐stream barriers such as weirs prevent fish migration and the impact can be particularly severe for diadromous species. Fishways are frequently installed on in‐stream barriers to reconnect migratory pathways and rehabilitate diadromous fish populations. Sequential fishways may be necessary in rivers where multiple barriers prevent migration. We monitored a coastal fish community's response to fish passage restoration at 10 predominantly low‐level weirs in the freshwater reaches of the Nepean River in southeastern Australia. Few studies have simultaneously assessed fish community passage at successive fishways within a river system. Prior to the installation of the fishways, there was a gradient of reduced species diversity in an upstream direction including the absence of many diadromous species, despite the regular inundation frequency of most weirs. Following the installation of the fishways, species diversity was still greater in the downstream monitoring sites; however, there was evidence of a positive change in fish community structure in middle and upstream sites. Most notably, three diadromous species rapidly expanded their distribution upstream and one amphidromous species expanded its downstream distribution. This study demonstrates appropriately designed successive fishways can successfully reconnect river systems for an entire fish community, encompassing species with a broad range of swimming abilities and diverse life histories.

The Microbial Composition of Bacteroidetes Species in Ulcerative Colitis Is Effectively Improved by Combination Therapy With Fecal Microbiota Transplantation and Antibiotics.

We previously reported that fresh fecal microbiota transplantation (FMT) after triple-antibiotic therapy (amoxicillin, fosfomycin, and metronidazole [AFM]; A-FMT) synergistically contributed to the recovery of phylum Bacteroidetes composition associated with the endoscopic severity and treatment efficacy of ulcerative colitis (UC). Here, we performed further microbial analyses using a higher-resolution method to identify the key bacterial species in UC and determine whether viable Bacteroidetes species from donor feces were successfully colonized by A-FMT. The taxonomic composition of Bacteroidetes in 25 healthy donors and 27 UC patients at baseline was compared at the species level using a heat-shock protein (hsp) 60-based microbiome method. Microbiota alterations before and after treatment of UC patients were also analyzed in 24 cases (n = 17 A-FMT; n = 3 mono-AFM; n = 4 mono-FMT). We found species-level dysbiosis within the phylum Bacteroidetes in UC samples, which was associated with reduced species diversity, resulting from hyperproliferation and hypoproliferation of particular species. Moreover, in responders treated with A-FMT, diversity was significantly recovered at 4 weeks after a fresh round of FMT, after which high degrees of similarity in Bacteroidetes species composition among recipients and donors were observed. A-FMT alleviated intestinal dysbiosis, which is caused by the loss of Bacteroidetes species diversity in patients with UC. Eradication of dysbiotic indigenous Bacteroidetes species by AFM pretreatment might promote the colonization of viable Bacteroidetes cells, thereby improving the intestinal microbiota dysbiosis induced by UC. Our findings serve as a basis for further investigations into the mechanisms of FMT.

Evidence of multiple colonizations as a driver of black fly diversification in an oceanic island.

True oceanic islands typically host reduced species diversity together with high levels of endemism, which make these environmental set-ups ideal for the exploration of species diversification drivers. In the present study, we used black fly species (Diptera: Simuliidae) from Reunion Island as a model to highlight the main drivers of insect species diversification in this young and remote volcanic island located in the Southwestern Indian Ocean. Using local and regional (Comoros and Seychelles archipelagos) samples as well as specimens from continental Africa, we tested the likelihood of two distinct scenarios, i.e. multiple colonizations vs. in-situ diversification. For this, posterior odds were used to test whether species from Reunion did form a monophyletic group and we estimated divergence times between species. Three out of the four previously described Reunion black fly species could be sampled, namely Simulium ruficorne, Simulium borbonense and Simulium triplex. The phylogenies based on nuclear and mitochondrial markers showed that S. ruficorne and S. borbonense are the most closely related species. Interestingly, we report a probable mitochondrial introgression between these two species although they diverged almost six million years ago. Finally, we showed that the three Reunion species did not form a monophyletic group, and, combined with the molecular datation, the results indicated that Reunion black fly diversity resulted from multiple colonization events. Thus, multiple colonizations, rather than in-situ diversification, are likely responsible for an important part of black fly diversity found on this young Darwinian island.

The 'filtering' metaphor revisited: competition and environment jointly structure invasibility and coexistence.

'Filtering', or the reduction in species diversity that occurs because not all species can persist in all locations, is thought to unfold hierarchically, controlled by the environment at large scales and competition at small scales. However, the ecological effects of competition and the environment are not independent, and observational approaches preclude investigation into their interplay. We use a demographic approach with 30 plant species to experimentally test: (i) the effect of competition on species persistence in two soil moisture environments, and (ii) the effect of environmental conditions on mechanisms underlying competitive coexistence. We find that competitors cause differential species persistence across environments even when effects are lacking in the absence of competition, and that the traits which determine persistence depend on the competitive environment. If our study had been observational and trait-based, we would have erroneously concluded that the environment filters species with low biomass, shallow roots and small seeds. Changing environmental conditions generated idiosyncratic effects on coexistence outcomes, increasing competitive exclusion of some species while promoting coexistence of others. Our results highlight the importance of considering environmental filtering in the light of, rather than in isolation from, competition, and challenge community assembly models and approaches to projecting future species distributions.

Intensive land-use drives regional-scale homogenization of plant communities

Intensive anthropogenic land-use causes habitat loss and landscape homogenization, which leads to the decrease of biodiversity and ecosystem degradation. Therefore, it is important to study the influence of landscape heterogeneity on biodiversity. In this study, vegetation surveys conducted at 53 sites in the Tabu River basin, located at the agro-pastoral ecotone of Inner Mongolia of China, revealed 146 species. Species diversity was evaluated at three scales: species richness within patches (alpha diversity), between patches (beta diversity) and at the landscape scale (gamma diversity). We analyzed landscape heterogeneity (LHtotal) and its driving factors including environmental variables (LHDFenv-var, such as precipitation and altitude), environmental heterogeneity (LHDFenv-het) and human activities (LHDFhum). We used structural equation modeling (SEM) to evaluate the response of species richness to landscape heterogeneity at three scales and determined the relative contribution of driving factors in explaining species diversity at these scales. The results of the study are summarized as follows: 1) Alpha diversity was the dominant component of gamma diversity in the Tabu River basin in Inner Mongolia. 2) There is no significant correlation (P = 0.512) between alpha diversity and LHtotal; with the increase of LHtotal beta and gamma diversities showed hump-shaped relationships. 3) LHDFenv-het was the primary factor in maintaining alpha diversity, with heterogeneity of mean annual precipitation (MAP), temperature (MAT) and altitude (ALT) acting as three largest contributors. LHDFhum primarily contributed to the maintenance of beta diversity. 4) LHDFhum was the primary contributor to gamma diversity, and human activity exceeded threshold values for positive effects. Based on our findings we suggest liming agricultural use along the river to prevent reductions in species diversity.

Comparison of aboveground vegetation and soil seed bank composition at sites of different grazing intensity around a savanna-woodland watering point in West Africa.

Grazing removes a plant's aboveground vegetative and reproductive tissues and can modify the soil seed bank, potentially impacting the restoration of preferred species. Knowledge about aboveground vegetation and species composition of soil seed bank and the processes that contribute to vegetation recovery on and surrounding watering points subjected to grazing is lacking. Successful restoration strategies hinge on addressing these knowledge gaps. We assessed the effects of livestock grazing on aboveground vegetation and soil seed bank characteristics along a river bank and surrounding areas subject to different grazing intensities and draw implications for restoration. Plots (50 × 50m) were established along five transects representing differing levels of grazing intensity. Soil samples were taken from three layers within each plot to determine soil properties and species composition of soil seed bank using the seedling emergence method. Heavy grazing resulted in the disappearance of perennial grasses, a reduction in species diversity and a decrease in soil nutrients with increased soil depth. Overall, the similarity between the extant aboveground vegetation and flora within the soil seed bank was low. The soil seed bank was dominated by herbaceous species and two woody species, suggesting that many woody species are not accumulating in the soil. With increasing soil depth, the seed density and richness declined. Canonical correspondence analyses (CCAs) showed that emerged seedlings from the soil seed bank were significantly influenced by soil carbon, organic matter, total nitrogen, total potassium and soil cation exchange capacity. This finding suggests that current grazing practices have a negative impact on the vegetation surrounding watering points; hence there is a need for improved grazing management strategies and vegetation restoration in these areas. The soil seed bank alone cannot restore degraded river banks; active transfer of propagules from adjacent undisturbed forest areas is essential.