排序方式: 共有38条查询结果,搜索用时 62 毫秒
21.
陕甘宁地区根瘤菌数值分类与DNA同源性分析 总被引:13,自引:1,他引:12
在陕甘宁地区根瘤菌资源调查的基础上,选取其中与黄芪、岩黄蓍、木兰、鸡眼草及胡枝子共生的40株快生根瘤菌和25株参比菌株,对133项表型性状进行聚类分析,在82%的相似性水平上构成5个不同于已知种的新亚群.对第1、2、3、4亚群x(G+C)/%测定及DNA同源性分析结果表明,4个亚群x(G+C)/%含量均处于Rhizobium属范围;各亚群内菌株DNA同源性均在75%以上,每个亚群中心菌株与13个已知种模式菌株的DNA同源性均小于63%.从而证明,第1、2、3、4亚群为4个独立的快生根瘤菌新种群 相似文献
22.
山西吕梁山南段植物群落的数量分类和排序研究 总被引:4,自引:0,他引:4
运用TWINSPAN和DCA相结合的数量生态学方法对吕梁山南段云邱山的植物群落进行分类和排序.结果表明,TWINSPAN分类将74个样方划分为18个群丛;分类结果较好地反映了植物群落类型与环境梯度之间的关系,并在DCA二维排序图上得到较好的验证;对74个样方和优势种的DCA排序表明影响吕梁山南段植物群落分布的主导生态因子是水分和土壤,而认为干扰加剧了该区域植被的退化.图2表1参13 相似文献
23.
Holly Deary 《Journal of Environmental Planning and Management》2019,62(3):466-491
Rewilding, though a young term, already has numerous meanings. We use Q-methodology to investigate understandings and practices of rewilding amongst managers of wildland on 17 estates in the Scottish uplands. The estates, covering 207,200 ha, include all the main land ownership types in Scotland. All respondents value wildness and biodiversity highly, but the Q-study reveals significant divergence in the interpretations and practices of rewilding, especially concerning (i) the value of naturalness, (ii) the use of management interventions, (iii) the value of cultural heritage and traditional land uses, and (iv) the place of people within wildland. A tripartite taxonomy of wildland management approaches is developed, identifying three ‘centres of gravity’ along the continuum of viewpoints, emphasising, respectively, nature's autonomy, active restoration, and the maintenance of wildness within cultural landscapes. The taxonomy provides an analytic framework for evaluating the diverse and often conflicting aspirations for the management of wild places. 相似文献
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Matthew S. Leslie 《Conservation biology》2015,29(1):69-77
Cataloging biodiversity is critical to conservation efforts because accurate taxonomy is often a precondition for protection under laws designed for species conservation, such as the U.S. Endangered Species Act (ESA). Traditional nomenclatural codes governing the taxonomic process have recently come under scrutiny because taxon names are more closely linked to hierarchical ranks than to the taxa themselves. A new approach to naming biological groups, called phylogenetic nomenclature (PN), explicitly names taxa by defining their names in terms of ancestry and descent. PN has the potential to increase nomenclatural stability and decrease confusion induced by the rank‐based codes. But proponents of PN have struggled with whether species and infraspecific taxa should be governed by the same rules as other taxa or should have special rules. Some proponents advocate the wholesale abandonment of rank labels (including species); this could have consequences for the implementation of taxon‐based conservation legislation. I examined the principles of PN as embodied in the PhyloCode (an alternative to traditional rank‐based nomenclature that names biological groups based on the results of phylogenetic analyses and does not associate taxa with ranks) and assessed how this novel approach to naming taxa might affect the implementation of species‐based legislation by providing a case study of the ESA. The latest version of the PhyloCode relies on the traditional rank‐based codes to name species and infraspecific taxa; thus, little will change regarding the main targets of the ESA because they will retain rank labels. For this reason, and because knowledge of evolutionary relationships is of greater importance than nomenclatural procedures for initial protection of endangered taxa under the ESA, I conclude that PN under the PhyloCode will have little impact on implementation of the ESA. Impactos de la Nomenclatura Filogenética sobre la Eficiencia del Acta Estadunidense para las Especies en Peligro 相似文献
26.
Alpina Begossi Fernando Dias de Ávila-pires 《Environment, Development and Sustainability》2003,5(1-2):179-195
Latin America comprehends notable variations in terms of natural environment, availability of natural resources, living standards, and demographic patterns. Latin America is a mosaic of cultures, post- and pre-Columbian. The rich variety of life forms discovered and described by chroniclers and traveling naturalists in the Neotropics contributed to the proposal, in mid-XVIIIth century, of a new system of classification and a scientific code of nomenclature for all organisms. Biodiversity was, for many centuries, a source of resources to be exploited in natura. In scientific circles, its inventory became the domain of taxonomists. But modern technology showed how important the miriad of life forms really are as sources of chemical molecules to be engineered as drugs and reassembled as novel manufactured products. We are on the brink of a new agricultural and medical revolution, thanks to the techniques of genetic engineering, which will lead eventually to the elimination of hunger and malnutrition.In this essay, the Brazilian environmental and social heterogeneity will serve as an example to illustrate some key points, which have influenced sustainability policies. The Amazon deforestation and indigenous knowledge (IK), subjects often associated with areas of high biodiversity, are usually the focus of environmental debates. The importance of IK in integrating development, reducing poverty and sustainability are considered together with the intellectual property rights of native populations.In the World Summit on Sustainable Development (WSSD) Implementation Plan, a few paragraphs were dedicated to Latin America, because of the pre-existing Action Platform on the Road to Johannesburg 2002, approved in Rio de Janeiro in October 2001. This paper calls attention to the need to draw up specific environmental policies for a region which shows an extremely high cultural and biological diversity, associated with a high availability of forests and water, among other resources. 相似文献
27.
紫色土硅酸盐细菌的表型特征及溶磷解钾能力 总被引:18,自引:0,他引:18
对40株分离自四川、重庆等地的代表笥紫色土中的硅酸盐细菌和1株参照菌株进行了52个表型性状的数值分析,探讨了硅酸盐细菌液体振荡培养后pH值、菌数变化与溶磷、解钾量之间的关系,结果表明:紫色土硅酸盐细菌绝大部分属于胶胨样芽孢杆菌(Bacillus mucilaginosus),但在个体和群体生长特征、碳氮源利用、硝酸盐还原能力、耐Ⅰ菌株在86%相似水平分为2个亚群,不同的硅酸盐细菌菌株的溶磷、解钾特性差异较大,具有溶磷解钾双重特性的菌株约占供试菌株(含参考菌株)的22%,只具溶磷特性的约占29%,其溶磷效果较显著(有效磷增加最高达40.64%),而解钾效果不明显(有效钾增加最多的只有7.9%)。供试紫色土硅酸盐细菌的溶磷、解钾特性与菌株生长过程中产酸有关,其溶磷、解钾量与培养液中pH值的降低呈正相关,图5表3参20。 相似文献
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Taxonomic Considerations in Listing Subspecies Under the U.S. Endangered Species Act 总被引:3,自引:0,他引:3
SUSAN M. HAIG†† ERIK A. BEEVER‡‡ STEVEN M. CHAMBERS† HOPE M. DRAHEIM‡ BRUCE D. DUGGER‡ SUSIE DUNHAM§ ELISE ELLIOTT-SMITH JOSEPH B. FONTAINE‡ DYLAN C. KESLER‡ BRIAN J. KNAUS§ IARA F. LOPES‡§§ PETE LOSCHL‡ THOMAS D. MULLINS LISA M. SHEFFIELD‡ 《Conservation biology》2006,20(6):1584-1594
Abstract: The U.S. Endangered Species Act (ESA) allows listing of subspecies and other groupings below the rank of species. This provides the U.S. Fish and Wildlife Service and the National Marine Fisheries Service with a means to target the most critical unit in need of conservation. Although roughly one-quarter of listed taxa are subspecies, these management agencies are hindered by uncertainties about taxonomic standards during listing or delisting activities. In a review of taxonomic publications and societies, we found few subspecies lists and none that stated standardized criteria for determining subspecific taxa. Lack of criteria is attributed to a centuries-old debate over species and subspecies concepts. Nevertheless, the critical need to resolve this debate for ESA listings led us to propose that minimal biological criteria to define disjunct subspecies (legally or taxonomically) should include the discreteness and significance criteria of distinct population segments (as defined under the ESA). Our subspecies criteria are in stark contrast to that proposed by supporters of the phylogenetic species concept and provide a clear distinction between species and subspecies. Efforts to eliminate or reduce ambiguity associated with subspecies-level classifications will assist with ESA listing decisions. Thus, we urge professional taxonomic societies to publish and periodically update peer-reviewed species and subspecies lists. This effort must be paralleled throughout the world for efficient taxonomic conservation to take place. 相似文献
29.
川西山区苹果属(Malus)植物野生种表型相似性和地理亲缘 总被引:4,自引:0,他引:4
用表型数量分析方法,结合地理分布对川西苹果属11个野生种进行研究,探讨其种间关系与地理分布的联系.得结论如下:1.不同系数的WPGMA和UPGMA聚类结果基本相同.表型数量骤类分析能大体反映近缘种间的亲缘关系;2.滇池海棠与沧江海棠在形态上高度相似,聚类图上极靠近,分布上相重叠,在塑定上有时感到困难;3.花叶海棠与变叶海棠和稻城海棠与小金海棠,从表型及分布上看显然是地理替代种;4.本文所列各种,大都分属两大植物区系范围内,例如花叶海棠属中国-日本区东范围内,变叶海棠属中国-喜马拉雅区系范围内;5.发现沿康定-理塘-巴塘(约(N)30°)存在一条南北物种分布的分界地带线,称康-巴线;沿岷江上游和大渡河流域也存在一条明显的地带线,称岷江-大渡河带,这一带就是中国-喜马拉雅区系和中国-日本区系的交界地带,通过这一地带有些向南分布的种可以越过康-巴线以东地区到达金沙江边,向北分布的种有时也可越过康-巴线以东达到岷江上游。在这南北和东西交界带上,不同物种会集,无疑是物种分化以及种质渗入十分活跃的地带;6.与其它地区相比较,四川西部山区是我国野生苹果植物分化的多样中心。 相似文献
30.
我国土壤水分状况的估算 总被引:7,自引:1,他引:7
根据改进的彭曼公式估算出的年干燥度,依据《中国土壤系统分类(修订方案)》中有关土壤水分状况的定量诊断指标,对我国的土壤水分状况进行估算,初步将我国划分为3个土壤水分区,6个土壤水分亚区,为我国土壤资源的定量评价与管理提供了科学依据 相似文献