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1.
The Middle East is an important contact zone for a considerable number of bird taxa from the western and eastern Palearctic and from the great Saharo-Sindian desert belt.Using WORLDMAP software,we analyzed the geographical distribution of secondary contact zones for parapatric species pairs of birds in the Middle East.We identified 56 species(29 species pairs)that make contact in the Middle East.The species pairs belong to three orders,i.e.Falconiformes,Piciformes,and Passeriformes.Almost half(46%)of these species pairs hybridize in their contact zones.Although contact zones occur over a large part of northern Middle East,spatially they were not evenly distributed.Contact zone richness was highest in the mountain ranges south of the Caspian Sea and the Caucasus.The hottest hotspots,where up to nine bird species pairs occur sympatrically,are situated in north-eastern Iran and Azerbaijan.We discuss the relevance of these hotspots for improving our understanding of the biogeography and evolution of the avifauna in the Middle East.  相似文献   

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【目的】为了解亚太地区途经上海崇明东滩湿地的迁徙鸟类群落变化、种间关系及迁徙机制,对崇明东滩鸟类国家级自然保护区环志鸟类群落的年际变化及迁徙物种种群数量种间变化的相关性进行研究。【方法】依照《鸟类环志技术规程》记录2005—2014年东滩湿地环志鸟类种类和数量,计算各年度内鸟类日均环志数量、物种比例、群落物种多样性指数及均匀度指数。【结果】10 a间共环志鸟类3目(鸻形目、鹳形目和鸥形目)8科51种。年环志种类在32~45种间波动,环志鸟类生物多样性指数为2.38~2.79,均匀度指数为0.68~0.76。日均环志数量呈下降趋势,从2006年日均环志59.07只下降到2014年日均环志17.13只。10年间年均环志量均超过环志总数1%的常见种有大滨鹬(Calidris tenuirostris)、黑腹滨鹬(C.alpine)、红颈滨鹬(C.ruficollis)等10种鸻鹬类; 对其进行两两种间种群数量随时间变化的相关性分析表明, 有14对呈显著正相关, 其中5对呈极显著正相关。【结论】环志鸟类迁徙路线上栖息湿地破坏与减少是导致环志鸟类种类和数量变化的主要潜在因素。  相似文献   

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水平井注水开发是中东地区孔隙型碳酸盐岩油藏的主体开发技术之一,而水平井水淹是制约注水开发效果的关键因素,为了尽快建立这类油藏的高效注水开发方式,需要对水平井水淹规律及其模式进行深入研究。与中国缝洞型碳酸盐岩油藏不同,中东孔隙型碳酸盐油藏具有发育生物碎屑灰岩、孔隙结构呈多模态、物性夹层及高渗条带普遍分布等特征,注水开发效果存在很大不确定性。岩心分析和测井解释表明高渗条带、断裂带和高黏流体是薄层孔隙型碳酸盐岩油藏水平井水淹的主控因素,导致水平段各部分见水不均衡,表现为点状见水局部水淹、多点见水局部水淹和线状见水整体水淹三种类型。基于主控地质因素和动态响应特征建立四类水平井水淹模式,并分析了不同模式下水平井见水规律、剩余油分布特征及开发调整对策。研究成果可以为中东地区孔隙型碳酸盐岩油藏水平井水淹治理和注水开发调整提供理论和技术指导。  相似文献   

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辽西冀北晚中生代的化石蜥蜴类(爬行纲:有鳞目)   总被引:1,自引:0,他引:1  
个蜥矢部部龙趾大具有辽西冀北晚中生代已记录的蜥蜴类化石共4属5种,及2个未命名属种。这些化石自下而上可划分4蜴类化石带:中侏罗世杨氏矢部龙带(Yabeinosaurus youngi Zone)、早白垩世早期长趾大凌河蜥-细小龙组合带(Dalinghosaurus longidigitus-Yabeinosaurus tenuis Assemblage Zone)、早白垩世早期细小矢带(Yabeinosaurus tenuis Zone)及早白垩世晚期炭德氏蜥带(Teilhardosaurus canbonarius Zone)凌河蜥-细小矢部龙组合带中的蜥蜴类属种最为丰富且分布较广,为研究早期蜥蜴类的地理地史分重要价值。布长等  相似文献   

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风电场建设对鸟类的影响是近年来鸟类生态学研究的热点之一。为了解广西兴安县兴安片区风电场的鸟类物种组成及其受风机的影响,本研究于2021年9-10月,采用样线法对该区域的鸟类多样性进行调查。调查结果显示,共发现鸟类10目34科68种,目、科种类最多的分别是雀形目(Passeriformes,54种)和鹟科(Muscicapidae,6种)。白头鹎(Pycnonotus sinensis)多度(49.7%)最高,其次是棕头鸦雀(Sinosuthora webbiana,19.1%)和暗绿绣眼鸟(Zosterops simplex,15.0%)。调查的各生境类型中,灌木林记录的鸟类种类(42种)最多。距风机700 m以外鸟类丰富度最高,且数量明显增加,而700 m范围内鸟类数量变化不明显。研究结果表明,鸟类受风机的影响可能与局部的地形和植被差异有关。  相似文献   

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新亚欧大陆桥沟通我国东中西三大经济地带,但目前的经济实力和在全国总格局中的作用还不能与沿海轴线和长江轴线相比为使其起到国家主轴框架的作用,必须加强沿桥绿洲经济带建设通过分析沿桥干旱区资源态势及经济基础、交通等基础设施及国际环境,探讨了绿洲发展的可能性,并提出研究出疆运油管道和进出疆第二铁路通道问题及解决干旱区水资源不足问题的对策  相似文献   

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Biodiversity hotspots have a prominent role in conservation biology, but it remains controversial to what extent different types of hotspot are congruent. Previous studies were unable to provide a general answer because they used a single biodiversity index, were geographically restricted, compared areas of unequal size or did not quantitatively compare hotspot types. Here we use a new global database on the breeding distribution of all known extant bird species to test for congruence across three types of hotspot. We demonstrate that hotspots of species richness, threat and endemism do not show the same geographical distribution. Only 2.5% of hotspot areas are common to all three aspects of diversity, with over 80% of hotspots being idiosyncratic. More generally, there is a surprisingly low overall congruence of biodiversity indices, with any one index explaining less than 24% of variation in the other indices. These results suggest that, even within a single taxonomic class, different mechanisms are responsible for the origin and maintenance of different aspects of diversity. Consequently, the different types of hotspots also vary greatly in their utility as conservation tools.  相似文献   

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McBrearty S  Jablonski NG 《Nature》2005,437(7055):105-108
There are thousands of fossils of hominins, but no fossil chimpanzee has yet been reported. The chimpanzee (Pan) is the closest living relative to humans. Chimpanzee populations today are confined to wooded West and central Africa, whereas most hominin fossil sites occur in the semi-arid East African Rift Valley. This situation has fuelled speculation regarding causes for the divergence of the human and chimpanzee lineages five to eight million years ago. Some investigators have invoked a shift from wooded to savannah vegetation in East Africa, driven by climate change, to explain the apparent separation between chimpanzee and human ancestral populations and the origin of the unique hominin locomotor adaptation, bipedalism. The Rift Valley itself functions as an obstacle to chimpanzee occupation in some scenarios. Here we report the first fossil chimpanzee. These fossils, from the Kapthurin Formation, Kenya, show that representatives of Pan were present in the East African Rift Valley during the Middle Pleistocene, where they were contemporary with an extinct species of Homo. Habitats suitable for both hominins and chimpanzees were clearly present there during this period, and the Rift Valley did not present an impenetrable barrier to chimpanzee occupation.  相似文献   

10.
Rodrigues AS 《Nature》2007,450(7171):E19; author reply E20
Using data on the global distribution of mammal, bird and amphibian species, Grenyer et al. conclude that planning based on individual taxa does not provide efficient solutions for the conservation of other taxa. They also report that the performance of existing global conservation strategies-endemic bird areas, biodiversity hotspots and global 200 ecoregions-in representing those taxa is often no better (and in some cases worse) than random. I argue here that the methodology used by Grenyer et al. was not appropriate for purported globally comprehensive analyses. Focusing on analyses of rare species as an example, I demonstrate how the data actually reveal substantial cross-taxon surrogacy and good performance of existing global conservation strategies.  相似文献   

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This paper presents the results of a detailed study of mortality profiles of the large herbivores from the Middle Palaeolithic (MP) bone assemblage of the Lingjing Xuchang Man Site, Henan Province. Based on the analysis of the crown heights of fossil teeth from this assemblage, we come to a conclusion that aurochs (Bos primigenius) and horse (Equus caballus) are the major prey species in this assemblage and the age structures of these animals can be best described as the "prime-dominated pattern". This study confirmed the well-established notions at many Middle and Upper Palaeolithic sites across Eurasia and Africa that MSA/MP foragers were fully effective in hunting aggressive prey species, particularly aurochs and horse. This find indicates that the hunting behaviors and subsistence strategies were not significantly different between MP and UP (the Upper Palaeolithic) humans in East Asia and hence suggests the early emergence of the modern human behaviors in this area.  相似文献   

12.
岩体动静力稳定分析的三维离散元数值模型   总被引:7,自引:0,他引:7  
离散单元法是一种适用于不连续岩体稳定分析的数值方法,可用于模拟岩体的大变形及系统的失稳破坏过程。提出了一种可用于岩体动静力稳定分析的三维离散元模型的凸多面体角边修圆模式及接触关系检测算法,此法将接触区域分为角区域、边区域和面区域,采用分级检索。对于接触刚度、阻尼系数、时步等参数作了讨论,同时建立了相应的动力学模型,并验证了振动台上的两刚块振动实验结果。结果表明:计算所得的加速度、位移过程曲线与试验结果吻合较好。该模型可分析在静力与动力作用下岩体的大变形失稳过程。  相似文献   

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Hydrothermal circulation at the axis of mid-ocean ridges affects the chemistry of the lithosphere and overlying ocean, supports chemosynthetic biological communities and is responsible for significant heat transfer from the lithosphere to the ocean. It is commonly thought that flow in these systems is oriented across the ridge axis, with recharge occurring along off-axis faults, but the structure and scale of hydrothermal systems are usually inferred from thermal and geochemical models constrained by the geophysical setting, rather than direct observations. The presence of microearthquakes may shed light on hydrothermal pathways by revealing zones of thermal cracking where cold sea water extracts heat from hot crustal rocks, as well as regions where magmatic and tectonic stresses create fractures that increase porosity and permeability. Here we show that hypocentres beneath a well-studied hydrothermal vent field on the East Pacific Rise cluster in a vertical pipe-like zone near a small axial discontinuity, and in a band that lies directly above the axial magma chamber. The location of the shallow pipe-like cluster relative to the distribution and temperature of hydrothermal vents along this section of the ridge suggests that hydrothermal recharge may be concentrated there as a consequence of the permeability generated by tectonic fracturing. Furthermore, we interpret the band of seismicity above the magma chamber as a zone of hydrothermal cracking, which suggests that hydrothermal circulation may be strongly aligned along the ridge axis. We conclude that models that suggest that hydrothermal cells are oriented across-axis, with diffuse off-axis recharge zones, may not apply to the fast-spreading East Pacific Rise.  相似文献   

15.
昆明动物园野生鸟类群落及与环境的关系   总被引:2,自引:0,他引:2  
为摸清城市公园鸟类群落的结构及与环境的关系,我们于1989年12月至1990年5月对昆明圆通山动物园的鸟类先后进行过16次调查统计,调查中共录得野生鸟类46种,数量合计517只,其中非雀形目鸟类9种,雀形目鸟类37种.并根据优势种及其所处的地位将该公园的鸟类群落定为树麻雀-黄眉柳莺-鹊鸲群落.并对该鸟类群落的结构特征及与环境的关系进行了分析研究.  相似文献   

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选取正在迅速城镇化的浙江省杭州市瓶窑镇,按其自然环境梯度设置调查样带,采用GIS软件MapInfoprofessional 6.5 SCP对景观单元特征指数(斑块数、斑块密度、边界密度)、景观异质性指数(破碎度指数、蔓延度指数、景观多样性指数、优势度指数、均匀度指数)和鸟类群落多样性指数进行分析.结果表明,作为过渡区域的城乡交错区和农林交错区表现出较高的景观破碎化,景观多样性程度也较高;城区人工景观规划单一,异质性程度较低;林区主要由人工种植的次生林构成,结构简单,景观多样性最低.比较分析不同景观格局指数与鸟类多样性指数间的变化趋势,交错区域的斑块密度、边界密度和破碎度指数明显高于临近区域,鸟类多样性也高于临近区域,鸟类多样性指数与景观多样性指数之间呈明显的正相关.景观多样性最高的农林交错区,鸟类多样性也最高.  相似文献   

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2016年11月~2017年10月,采用样线调查法和定点观察法对水门塘国家级水利风景区的鸟类多样性进行了调查,共记录到鸟类14目39科108种,其中国家1级保护鸟类1种,国家2级保护鸟类4种,安徽省地方重点保护鸟类24种。居留类型组成中,有留鸟36种(占33.3%),夏候鸟25种(占23.2%),冬候鸟24种(占22.2%),旅鸟23种(占21.3%);区系组成包括古北界51种(占47.2%),东洋界16种(占14.8%),广布种41种(占38.0%)。对鸟类种类、数量和多样性的分析结果表明,鸟类物种多样性及其数量的季节性变化较为明显,春秋两季鸟类种类较多,多样性指数和均匀度指数也相对较高;冬夏两季鸟类数量较多,但多样性指数和均匀度指数均较低。  相似文献   

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中国三叠纪含牙形刺地层   总被引:2,自引:0,他引:2  
十年来,中国三叠纪牙形刺地层的研究取得了很大的成绩。1.三叠纪含牙形刺地层主要分布在中国南方,尤其在昆仑-秦岭一线以南,此地层发育程度由西向东逐渐减弱,例如:西部珠峰地区分布在整个三叠系地层中,向东到下扬子地区,主要分布在下三叠统中。2.中国三叠纪牙形刺很丰富,已发现39属,230种,可划分成24个带。3.在奥伦尼阶,我国牙形刺根据生态可划分为两种类型:(1)盆地型(珠峰类型),(2)台地型(湖北利川类型)。  相似文献   

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几种真菌酯酶同工酶的聚丙烯酰胺凝胶电泳的初步研究   总被引:3,自引:0,他引:3  
用聚丙烯酰胺凝胶圆盘电泳测定裂褶菌(Schizophyllm commune),8111(P1eurotug sp.)佛罗里达(Pleurotus florida),华丽侧耳(Pleurotus sp.)的酯酶同工酶在不同生长时期和不同条件下的酶谱。结果分析认为酯酶同工酶谱可作为研究真菌遗传变异和亲缘关系的一种手段,也是鉴定真菌种属分类的一种方法。实验的结果如下: 1.在培养过程中,菌丝体的酶带数目是不断增加的。 2.幼菌丝体的酶带与子实体的酶带是有区别的,因此必需利用晚期的菌丝体作为电泳样品,因为老的菌丝体接近于子实体的酶带。 3.裂褶菌的酶带与另外三个种的酶带是很不相同的,因此,裂褶菌和它们分属于不同的科。 4.华丽侧耳(Pleurotug sp.)的酶带是相似于佛罗里达侧耳(Pleurotus florida)的酶带,因此,华丽侧耳与佛罗里达侧耳是同一个种,8111的酶带是不同于佛罗里达侧耳,因此8111是侧耳属的另一个种。  相似文献   

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