养殖对曼氏无针乌贼(Sepiella maindroni)群体遗传多样性的影响   总被引：3，自引：2，他引：1  

宋微微  王春琳 《海洋与湖沼》2009,40(5):590-595

采用24条随机引物对曼氏无针乌贼1个野生群体和5代养殖群体共120个个体(每个群体20个个体)进行了RAPD群体遗传多样性分析,共扩增出119个位点,片段大小为400-2800bp,平均每条引物的扩增带数为4.96条。各群体的多态位点数19-24个不等,多态位点比例为13.33%-20.16%,Shannon指数为0.0768-0.1018。6个群体的平均杂合度为0.0825-0.1231,期望杂合度为0.1325-0.1524,平均杂合子偏离指数均为负值,表明存在杂合子缺失的现象。乌贼6个群体遗传分化系数FST值在0.0188-0.2436,其中最大出现在野生群体和第5代养殖群体之间。表明6个群体间遗传分化已基本处于遗传分化中等的范围内,而野生群体和第5代养殖群体之间已接近中等分化的底线。分子方差分析(AMOVA)结果表明,6个群体的遗传变异中有29.34%是由不同群体间的基因差异造成的。而如果将养殖后的5代群体作为一个总的群体,养殖群体内部有19.38%是由群体间的差异造成的。由此可见,养殖后的曼氏无针乌贼群体相比野生群体多样性指数有所降低,且随着养殖时间的增长养殖群体内部开始出现分化。  相似文献   

Observations of urban and suburban environments with global satellite scatterometer data   总被引：1，自引：0，他引：1  

S.V. Nghiem  D. Balk  E. Rodriguez  G. Neumann  A. Sorichetta  C. Small  C.D. Elvidge 《ISPRS Journal of Photogrammetry and Remote Sensing》2009,64(4):367-380

A global and consistent characterization of land use and land change in urban and suburban environments is crucial for many fundamental social and natural science studies and applications. Presented here is a dense sampling method (DSM) that uses satellite scatterometer data to delineate urban and intraurban areas at a posting scale of about 1 km. DSM results are analyzed together with information on population and housing censuses, with Landsat Enhanced Thematic Mapper Plus (ETM+) imagery, and with Defense Meteorological Satellite Program (DMSP) night-light data. The analyses include Dallas-Fort Worth and Phoenix in the United States, Bogotá in Colombia, Dhaka in Bangladesh, Guangzhou in China, and Quito in Ecuador. Results show that scatterometer signatures correspond to buildings and infrastructures in urban and suburban environments. City extents detected by scatterometer data are significantly smaller than city light extents, but not all urban areas are detectable by the current SeaWinds scatterometer on the QuikSCAT satellite. Core commercial and industrial areas with high buildings and large factories are identified as high-backscatter centers. Data from DSM backscatter and DMSP nighttime lights have a good correlation with population density. However, the correlation relations from the two satellite datasets are different for different cities indicating that they contain complementary information. Together with night-light and census data, DSM and satellite scatterometer data provide new observations to study global urban and suburban environments and their changes. Furthermore, the capability of DSM to identify hydrological channels on the Greenland ice sheet and ecological biomes in central Africa demonstrates that DSM can be used to observe persistent structures in natural environments at a km scale, providing contemporaneous data to study human impacts beyond urban and suburban areas.  相似文献   

南极菲尔德斯半岛潮间带南极帽贝的种群生态学研究──夏季种群数量变化和垂直分布   总被引：1，自引：1，他引：0  

黄凤鹏  吴宝铃  徐汝梅  蒋南青 《海洋与湖沼》1999,30(6):616-623

于1994年12月—1995年3月（南极夏季）期间,对南极菲尔德斯半岛卵石滩、岩石滩潮间带南极帽贝的种群数量、垂直分布进行了定点、定时、定量的调查和观察。结果表明,南极帽贝的种群数量有明显下降,分别仅为起始数量的35％和52％。卵石滩潮间带的帽贝分布于中潮区及低潮区,尤其是低潮区,且有随季节（冬季来临）向潮下带移动的趋势。岩石滩潮间带的帽贝具有类似的垂直分布特征,但其在分布带上的发生频次有很大差异,呈波动状态。在垂直岩面上,帽贝数量在低潮区的底部更为集中。讨论了导致数量变化、垂直分布的可能原因。今后有必要深入研究种群数量的时空动态及其调控机理。  相似文献   

Population Dynamics and Reproductive Traits of Phytal Gastropods in Seagrass Bed in Otsuchi Bay, North-Eastern Japan   总被引：1，自引：0，他引：1  

Tetsuhiko Toyohara  Masahiro Nakaoka  & Keiko Aioi 《Marine Ecology》1999,20(3-4):273-289

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Multi-Method Research: An Introduction to Its Application in PopulationGeography     

John H. McKendrick 《The Professional geographer》1999,51(1):40-50

This paper sets the context for four papers on multi-method research inpopulation geography. It begins by outlining the various ends to which multi-method research may be employed. The focus then shifts to the broader plane of method, epistemology, and research design. It is argued that epistemological position only determines how methods can be used: it does not preclude the use of particular methods. The possibilities for multi-method research are therefore considerable. Finally, some issues pertaining to multi-method research thathave not yet been resolved are raised for future debate.  相似文献   

Development implications of demographic trends and projections for an arid region:: the case of the Badia Research and Development Project area of Jordan     

Allan M. Findlay  Mohammed Maani 《Applied geography (Sevenoaks, England)》1999,19(4):29

Development planners in arid areas face many difficulties in preparing appropriate strategies. Their task is made harder by the dearth of reliable demographic information. This paper presents population projections for the arid area of eastern Jordan covered by the Badia Research and Development Project and evaluates the economic and social implications of these projections over the next 20 years. The paper argues that conventional demographic forecasting methods are extremely problematic when applied to a population such as this. Furthermore, the pastoral economy, which has in the past been the main source of livelihood, cannot hope to sustain the region's future population. High fertility rates will continue to place great stress on the educational and health infrastructure. If appropriate planning responses are not achieved, the demographic regime of the Badia project area and the quality of life of the population may continue to diverge from the patterns found in other parts of Jordan.  相似文献   

Marine ecosystem management: Fish abundance and size under exploitation     

Joe Horwood 《Marine Policy》2010

This study is targeted on policy makers and environmental scientists to illustrate the typical historical scale of depletion of our fish stocks, and what current and emerging legislation might mean for fisheries management and the metrics of fish stocks. The population demography of the Bristol Channel sole is described since 1820. Their decline in abundance, and change in length compositions, are modelled. By 2000, the mature stock had been depleted to less than 5% of its original size, and larger sole were rarely caught. The implications of maximum sustainable yield targets, and of good environmental status, are examined.  相似文献   

中国大陆地震灾害分区人员死亡评估模型研究     

亓凤娇  李雯  苏鹤军  陈文凯  王紫荆  苏浩然 《地震》2022,42(1):70-84

针对现阶段地震人员死亡评估模型在评估特定区域地震时评估结果误差较大的问题,结合中国地震灾害特点、人口分布情况等,将中国大陆划分为西北、西南和大陆东部三个地区,并对各区域按照人口密度进行分级。采用多元非线性回归方法,选取震中烈度、震区面积、抗震设防烈度参数建立分区域的地震灾害人员死亡评估模型。研究结果表明,该模型在西北、西南地区的验证结果较好,适用于中国地震灾害情况,可以用于震后快速盲评估,在一定程度上能够避免评估不同震级、相同震中烈度和人口密度的地震时,出现相同结果的情况;虽然该模型在震例较少的大陆东部地区以及城市直下型地震中评估结果需要进一步改进,但为解决特定区域地震死亡评估中误差较大问题提供了思路,能够为震后应急指挥和救援提供数据参考。  相似文献   

基于形态性状的松江鲈鱼(Trachidermus fasciatus)种群鉴别   总被引：4，自引：0，他引：4  

王金秋  梁鸿子 《海洋与湖沼》2008,39(4)

采用差异系数（C．D）和均数差异显著性这两种数理统计分析方法,对松江鲈鱼的鸭绿江、青龙河和富春江三个群体的表型性状,即85个样本的19项形态性状,其中包括10项可数性状和9项可量性状的差异进行了分析研究。结果表明,这三个群体彼此间的C．D值均小于亚种分化的判定标准1．28的水平,即各群体间的差异尚未达到亚种分化的水平,仍属同一种群。形态性状均数差异显著性的检验结果显示,松江鲈鱼青龙河与富春江两群体之间的差异较小,而鸭绿江群体与这两者的差异相对较大。  相似文献   

中国沿海脉红螺(Rapana venosa)自然群体线粒体 DNA 16S rRNA遗传特性研究   总被引：7，自引：1，他引：6  

杨建敏  李琪  郑小东  宋志乐  王如才 《海洋与湖沼》2008,39(3):257-262

对中国沿海脉红螺7个自然居群的线粒体DNA 16S rRNA基因片段进行了扩增和测序,分析了107个个体511bp的碱基序列,结果没有发现插入,缺失突变的核苷酸位点.检测到了28个多态性核苷酸位点,共37种单倍型,单倍型1的同源性达到58.7%.大连居群的28l(G-A)和483(T- C)位点,烟台居群的17(A-G)位点、66(T- C)和247(T-C)位点,舟山居群的128(T-C)位点,秦皇岛居群的130(T-G)和161(A-G)位点,以及丹东居群的431(T-C)位点的变异可以作为居群分子遗传标记位点.居群内,烟台和大连居群的核苷酸差异数 K 以及平均核苷酸多样性指数 Pi 最高,青岛居群最低;居群间,大连居群在居群间核苷酸差异数K、居群间平均每位点核苷酸替代数Dxy 和居群间每位点净核苷酸替代数Da三个指标上都表现出比其他居群之间较高的水平,说明大连居群具有最为丰富的遗传多样性.  相似文献