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Climate drives differences in the germination niche of a globally distributed invasive grass

Journal of Plant Ecology 2020年第2期13卷 195-203页

作者： rebecca a.fletcher Kayla M.Varnon Jacob N.Barney Virginia Tech School of Plant and Environmental Sciences675 Old Glade RdBlacksburgVA 24061USA

外来入侵物种在入侵地经常面临很强的选择压力,这常常导致种内变异。在生活史事件发生的时间上,种群分化对气候梯度的响应被认为是促进许多入侵物种扩张的重要机制。对于产生种子的植物来说,种子萌发的时间决定了萌芽所经历的第一个环... 详细信息

外来入侵物种在入侵地经常面临很强的选择压力,这常常导致种内变异。在生活史事件发生的时间上,种群分化对气候梯度的响应被认为是促进许多入侵物种扩张的重要机制。对于产生种子的植物来说,种子萌发的时间决定了萌芽所经历的第一个环境条件,这对入侵植物的成功定植、种群建立和传播具有重要意义——尽管对于萌发在植物入侵成功中所起的作用仍然知之甚少。在本研究中,我们评估了入侵植物石茅(Sorghum halepense)在北美分布的10个种群的种子萌发在温度和降水梯度上的动态变化,以及这种变化是否与本地气候有关。种子被放置于一个较宽的温度范围(11-48℃)以及两个水分梯度处理中。我们发现,石茅的种子可以在很宽的温度范围下萌发,但在不同的种群中,种子萌发的比例随温度和水分的不同而有较大的变化。有证据表明,当石茅的生长范围从温暖的气候扩展到寒冷的气候时,种子萌发温度的生态位也同时发生了向低温的转变。我们的研究结果表明,石茅种子的萌发已经适应了当地的气候,使其在整个生长范围内的萌发最大化,这可能是其入侵新环境的一个重要贡献因素。

关键词：适应种群变异石茅温度水分有效性

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Evidence for fine-scale habitat specialisation in an invasive weed

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Journal of Plant Ecology 2018年第2期11卷 189-199页

作者： Daniel Z.Atwater rebecca a.fletcher Christopher C.Dickinson Andrew H.Paterson Jacob N.Barney Virginia Tech Department of Plant PathologyPhysiology and Weed Science435 Old Glade RoadBlacksburgVA 24061USA University of Georgia Plant Genome Mapping Laboratory111 Riverbend RoadAthensGA 30606USA

Aims As an exotic species colonises a new continent,it must overcome enormous environmental variation in its introduced *** adaptation of introduced species has frequently been observed at the continent scale,particularly in response to latitudinal climatic ***,significant environmental heterogeneity can also exist at the landscape scale.A small number of studies have provided evidence that introduced species may also be capable of phenotypic and genetic differentiation at much smaller spatial *** example,previously we found US agricultural and non-agricultural populations of Sorghum halepense(Johnsongrass)to be phenotypically and genetically *** this study,we inves-tigated whether this phenotypic differentiation of agricultural and non-agricultural populations of *** is the result of fine-scale local *** We surveyed a nationally collected *** germplasm panel and also collected neighbouring agricultural and non-agricultural sub-populations of *** at four sites throughout Western Virginia,USA,raising seedlings in common conditions mimicking both agricultural and non-agricultural *** Findings At the national scale,we found evidence of habitat differentiation but not ***,at the local scale,we found evi-dence of specialisation in two of the four local populations to non-agricultural habitat,but no evidence of specialisation to agricultural *** results show that local specialisation is a possible,but not guaranteed consequence of kilometre-scale habitat heterogen-eity in invasive *** finding contributes to a growing aware-ness of the importance of fine-scale local adaptation in the ecology and management of introduced and weedy species.

关键词： Johnsongrass local adaptation rapid evolution Sorghum halepense(L.)

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High-flow oxygen via oxygenating mouthguard in short upper gastrointestinal endoscopy:A randomised controlled trial

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World Journal of Gastrointestinal Endoscopy 2022年第12期14卷 777-788页

作者： Kim Hay Be Leonardo Zorron Cheng Tao Pu Brett Pearce Matthew Lee Luke fletcher rebecca Cogan Philip Peyton Rhys Vaughan Marios Efthymiou Sujievvan Chandran Department of Gastroenterology and Hepatology Austin HealthHeidelberg 3084VictoriaAustralia Department of Anaesthesia and Pain Medicine Austin HealthHeidelberg 3084VictoriaAustralia Faculty of Medicine Dentistry and Health SciencesUniversity of MelbourneParkville 3010VictoriaAustralia

BACKGROUND Anaesthetic care during upper gastrointestinal(GI)endoscopy has the unique challenge of maintaining ventilation and oxygenation via a shared upper *** oxygen is recommended by international society guidelines,however,the optimal route or rate of oxygen delivery is not *** oxygen delivery devices have been investigated to improve oxygenation during upper GI endoscopy,however,these are limited by commercial availability,costs and in some cases,the expertise required for *** at our centre,higher flows of supplemental oxygen can safely be delivered via an oxygenating mouthguard routinely used during upper GI endoscopic *** To assess the incidence of hypoxaemia(SpO2<90%)in patients undergoing upper GI endoscopy receiving supplemental oxygen using an oxygenating mouthguard at 20 L/min flow compared to standard nasal cannula(SNC)at 2 L/min *** A single centre,prospective,randomised clinical trial at two sites of an Australian tertiary hospital between October 2020 and September 2021 was *** undergoing elective upper gastrointestinal endoscopy under deep sedation were randomised to receive supplemental oxygen via high-flow via oxygenating mouthguard(HFMG)at 20 L/min flow or SNC at 2 L/min *** primary outcome was the incidence of hypoxaemia of any duration measured by pulse ***-related,procedural-related,and sedation-related adverse events and patient-reported outcomes were also *** Three hundred patients were *** patients were excluded after randomisation.292 patients were included in the intention-to-treat *** incidence of hypoxaemia was significantly reduced in those allocated *** patients(4.4%)allocated to HFMG experienced an episode of hypoxaemia,compared to thirty-four(22.1%)patients allocated to SNC(P value<0.001).No significant difference was observed in the rates of adverse events or patient-reported outcome meas

关键词： Upper gastrointestinal endoscopy Supplementary oxygen Hypoxaemia Oxygenating mouthguard

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塔塔需备总资本豢养“虎豹”

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汽车与配件 2008年第15期 32-33页

作者： Ian fletcher rebecca Wright

经济状况和未来的排放要求可能对这两个品牌不利,塔塔应为此做好准备,并具有足够的资本,才能安全渡过这场经济风暴。

关键词：资本塔豢养经济状况排放要求豹虎

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