997 resultados para 13-126


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◾ Report of Opening Session (p. 1) ◾ Report of Governing Council (p. 15) ◾ Report of the Finance and Administration Committee (p. 47) ◾ Reports of Science Board and Committees: Science Board Inter-sessional Meeting (p. 63); Science Board (p. 73); Biological Oceanography Committee (p. 87); Fishery Science Committee (p. 95); Marine Environmental Quality Committee (p. 105); MONITOR Technical Committee (p. 115); Physical Oceanography and Climate Committee (p. 125); Technical Committee on Data Exchange (p. 133) ◾ Reports of Sections, Working and Study Groups: Section on Carbon and Climate (p. 139); Section on Ecology of Harmful Algal Blooms in the North Pacific (p. 143); Working Group 18 on Mariculture in the 21st Century - The Intersection Between Ecology, Socio-economics and Production (p. 147); Working Group 19 on Ecosystem-Based Management Science and its Application to the North Pacific (p. 151); Working Group 20 on Evaluations of Climate Change Projections (p. 157); Working Group 21 on Non-indigenous Aquatic Species (p. 159); Study Group to Develop a Strategy for GOOS (p. 165) ◾ Reports of the Climate Change and Carrying Capacity Scientific Program: Implementation Panel on the CCCC Program (p. 169); CFAME Task Team (p. 175); MODEL Task Team (p. 181) ◾ Reports of Advisory Panels: Advisory Panel for a CREAMS/PICES Program in East Asian Marginal Seas (p. 187); Advisory Panel on Continuous Plankton Recorder Survey in the North Pacific (p. 193); Advisory Panel on Iron Fertilization Experiment in the Subarctic Pacific Ocean (p. 197); Advisory Panel on Marine Birds and Mammals (p. 201); Advisory Panel on Micronekton Sampling Inter-calibration Experiment (p. 205) ◾ Summary of Scientific Sessions and Workshops (p. 209) ◾ Membership List (p. 259) ◾ List of Participants (p. 277) ◾ List of PICES Acronyms (p. 301) ◾ List of Acronyms (p. 303)

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This workshop was convened to begin building a foundation of understanding for developing and evaluating proposed measures for the rational management of the blue crab fishery in Chesapeake Bay. Our goal was to generate a summary of knowledge of blue crab stock dynamics. Specifically, we intended to address, and hoped to estimate, the basic parameters of an exploited stock - growth, mortality, natality, migration rates, sex ratios and abundance. In one sense these objectives were simply a means for organizing our discussions. A second objective was to compile at the workshop pertinent data held by the major research institutions on Chesapeake Bay so all participants could see the kinds and extent of existing data. As with many stock assessment problems, tailoring an estimating procedure around known existing data can be more productive than deciding on a procedure and then trying to find the required data in someone else's files. Authors of papers contributed to the report: B.S. Hester and P.R. Mundy (p. 50); Qisheng Tang (p. 86); L. Eugene Cronin (p. 111); J.R. McConaugha (p. 128); Cluney Stagg and Phil Jones (p. 153).

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EXTRACT (SEE PDF FOR FULL ABSTRACT): Pollen from the upper 2.75 m of a core taken 200 km west of the Golfo de Guayaquil, Ecuador (Trident 163-13, 3° S, 84° W, 3,000 m water depth) documents changes in Andean vegetation and climate of the Cordillera Occidental for ~17,000 years before and after the last glacial maximum.

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近几十年来,栽培作物及其野生近缘(祖先)种的群体遗传结构和进化历史的研究日益受到关注,因为此类研究不仅能加深人们对作物起源和驯化的认识,而且有助于作物野生资源的开发以及作物的遗传改良。分子谱系地理分析(Molecular phylogeography)是此类研究中的重要手段之一,能够有效地了解近缘群体的进化历程以及重建作物的驯化历史。菰(Zizania latifolia Turcz.)是东亚广泛分布、具有重要价值的水生草本植物,其栽培型—茭白是中国第二大水生蔬菜。尽管已有不少涉及此类群的研究,但迄今我们对菰的群体遗传结构和进化历史以及茭白的起源几乎一无所知。本研究从29个基因片段中筛选了2个在菰种内水平上具有显著变异量的核基因片段,进行了分子谱系地理研究,揭示了菰的遗传多样性水平及其地理分布格局,探讨了菰的群体演化历史,并初步探讨了茭白的起源和驯化历史。主要结果如下: 1)基因片段筛选 开展分子谱系地理学研究,需要采用具有显著种内变异的分子标记,为此我们通过预实验对一批备选基因片段进行了筛选。在18个叶绿体和2个线粒体片段中,测序的总长度达17100 bp,但没有发现任何变异位点。在9个核基因片段中,7个片段具有变异位点,但只有2个片段的变异量在1%以上,分别是Adh1a(2.70%)和GPATb(1.25%)基因。所以,本研究最后确定了采用这2个核基因片段来进行菰的分子谱系地理的研究。 2)Adh1a基因谱系地理分析 对来自21个天然群体126个个体,通过Adh1a基因的直接PCR和克隆测序共得到了252条序列,中性检测表明,Adh1a基因符合中性进化模型、没有重组并且有足够的变异量,适合用于进行菰的谱系地理研究和进化历史的推断。在物种水平上,菰的核苷酸多态性水平为θsil = 0.0089,跟一些作物近缘类群相比处于中等偏低的水平;不同群体的核苷酸多态性水平相差明显,多态性最高的群体出现在东北地区,并有从北向南递减的趋势。群体间存在着显著的遗传分化(FST = 0.481)表明群体之间的基因流有限。群体间的遗传距离与地理距离没有相关性,地理邻近的群体并没有共享关系相近的单倍型,整个群体缺乏明显的谱系地理结构。目前的遗传多样性分布格局可能是由于近几十年来的生境退化和丧失造成过去群体的片段化所致。根据群体遗传多样性水平的差异和基因谱系的地理分布格局以及分子钟估算的与北美近缘种的分化时间,我们推断菰的群体经历了从东北向华南逐步扩散的过程。 3)GPATb基因谱系地理分析 为更可靠地推断菰的谱系地理格局,我们选择了GPATb基因作为标记开展了进一步的分析。对相同的采样群体和个体共252条序列的分析表明,在物种水平上,GPATb的核苷酸多态性只相当于Adh1a基因的1/4。综合2个基因的结果,可以认为菰的核苷酸多态性水平是维持在较低的水平上。该位点体现的群体遗传分化也没有Adh1a基因明显。群体之间相近的遗传多样性水平和较低分化程度可能意味着该基因位点受到平衡选择作用的影响,这一推论也得到了中性检测结果的支持。因此,GPATb基因可能受到选择作用的影响,不能用来支持或推翻Adh1a基因的结果。 4)茭白的起源和驯化 对来自13个省份的65个茭白品种的Adh1a和GPATb基因片段进行测序,结果发现,所有的品种在这2个基因上都具有相同的基因型,Adh1a位点上表现为杂合体,而GPATb位点上则是纯合体。这说明在茭白的起源过程中发生了严重的驯化瓶颈效应,也即茭白是单次起源的,是从菰的少数几个甚至单个个体驯化而来。虽然文献考据表明,茭白最早的栽培地区为太湖流域,但我们的分子证据却并不支持其为茭白的驯化起源地点,而可能是在太湖流域以北地区起源的。鉴于采样的局限性,这一结论还有待于进一步的验证。同时2个基因的数据表明来自陕西、四川、云南、湖南和福建的6个菰群体可能是从人为引种的茭白逃逸成为野生的。因此,在以后野生菰群体的采集中,特别是在茭白种植地区,要在详细调查的基础上设计采集方案。