55 resultados para Multiple Species Conservation
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The Critically Endangered black crested gibbon Nomascus concolor of China, Laos and Vietnam is threatened by deforestation and habitat destruction but there have been no studies of how it uses its forest habitat, probably because of the typically rugged t
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The human genome project has been recently complemented by whole-genome assessment sequence of 32 mammals and 24 nonmammalian vertebrate species suitable for comparative genomic analyses. Here we anticipate a precipitous drop in costs and increase in sequ
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On the Qinghai-Tibet plateau increased livestock numbers have resulted in degradation of the grasslands with potential impacts on native biodiversity. Concurrently, perceived increases in populations of native small mammals such as plateau pikas (Ochotona curzoniae) have led to poisoning programs, with uncertain impacts on species such as ground-nesting birds. We explored the relationships between the local seasonal abundance of small birds and (1) the density of pika burrows; (2) livestock grazing practices; and (3) local poisoning of pikas. Around Naqu prefecture, central Tibet, we used a nested experimental design to collect data from areas rested from grazing over summer, nearby areas with year-round grazing and areas subjected to pika poisoning. Additional data were collected from a site where grazing had not occurred for at least 4 years prior to the study. Poisoning pikas in spring had no detectable effect on the local abundance of birds the following autumn. However, two ground-nesting species, white-rumped and rufous-necked snowfinches, showed positive associations with the density of pika burrows, indicating that long-term 'pika poisoning could reduce the density of these species by reducing the density of pika burrows. Rufous-necked snowfinches and non ground-nesting species including horned larks and common hoopoes showed positive responses to reduced grazing pressure from livestock, particularly in the long-rested site, indicating current grazing levels could be having a negative impact on these species. Conservation of small passerine biodiversity in this system will require changed management practices for livestock and pikas that consider the complex three-way interaction between livestock grazing, pikas and small birds. (C) 2008 Elsevier Ltd. All rights reserved.
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The physical vapor transport (PVT) method is being widely used to grow large-size single SiC crystals. The growth process is associated with heat and mass transport in the growth chamber, chemical reactions among multiple species as well as phase change at the crystal/gas interface. The current paper aims at studying and verifying the transport mechanism and growth kinetics model by demonstrating the flow field and species concentration distribution in the growth system. We have developed a coupled model, which takes into account the mass transport and growth kinetics. Numerical simulation is carried out by employing an in-house developed software based on finite volume method. The results calculated are in good agreement with the experimental observation.
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The physical vapor transport (PVT) method is being widely used to grow large-size single SiC crystals. The growth process is associated with heat and mass transport in the growth chamber, chemical reactions among multiple species as well as phase change at the crystal/gas interface. The current paper aims at studying and verifying the transport mechanism and growth kinetics model by demonstrating the flow field and species concentration distribution in the growth system. We have developed a coupled model, which takes into account the mass transport and growth kinetics. Numerical simulation is carried out by employing an in-house developed software based on finite volume method. The results calculated are in good agreement with the experimental observation.
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悬崖代表着一个残遗的、较少受到干扰的古生境,悬崖也是生物多样性的避难所。这个特殊生境中分布种类丰富的稀有植物和特有植物,而这些稀有和特有植物又往往以悬崖为唯一的生境,在长期的演化历史进程中形成彼此相互适应的关系。这种分布在特殊生境中的稀有植物为保护研究提出了新的研究方向和问题。本文以蔷薇科的中国特有植物太行花(Taihangia rupestris Yü et Li)为对象,对这个仅分布在有限的地理范围内悬崖上的稀有物种进行了保护生物学的研究。 利用RAPD分子标记技术对太行花8个居群的遗传多样性和遗传结构进行了检测分析。结果表明太行花居群内维持着较高的遗传多样性水平,未显示遭受过严重遗传瓶颈的迹象。同时,居群间遗传分化显著,与居群间的地理距离相关,聚类分析得到的树系图与太行花种下两个变种(太行花原变种Taihangia rupestris var. rupestris和缘毛太行花Taihangia rupestris var. ciliate Yü et Li)的划分相符。 通过栽培实验,研究了太行花对光照和养分的反应,从生态学角度检测植物对环境因子变化的适应能力。结果表明光照处理显著影响太行花的气体交换参数,且显示出随季节不同而变化的趋势。在8月第一次测量时,光合速率随着光照水平的增加而增加;而在9月底第二次测量时,高光下植株的光合速率反低于中光条件下的植株。光合光反应曲线表明太行花对不同光照水平(高光、中光和低光)均显示出一定的光合适应性。 光照对太行花的生长反应、形态、解剖等指标均具有显著的作用。在收获时,高光下植物形成小而厚的叶片,更快的叶片形成速率足以弥补单叶面积上光合速率的下降,使植株维持最大的总生物量。中光条件下的植株具有更长的叶柄,更大的叶面积,大而薄的叶片,和更大的叶面积比,被认为是对较弱光照环境适应的表现。而光照对叶片的气孔指标(气孔密度、气孔指数和大小)没有作用,养分施加对太行花的影响也甚微。总体来说,太行花显示出对光照变化的生理适应性和形态可塑性,光照和养分这两个环境条件均非影响太行花局限分布的关键因素。 同时,我们采用扫描电镜手段跟踪观察了太行花的花的早期发育过程。太行花早期发育过程中苞片内残留的退化花痕迹表明,太行花的顶生单花其实是有限聚伞花序中其它花芽败育的结果,显示出从花序向单花演化的趋势。同时,雌蕊的发育在早期是正常的,未显示出退化痕迹。 根据以上结果表明,局限分布在特殊生境上的太行花并未显示出生理适应幅度的狭窄性和遗传多样性水平的降低,因此,太行花在长期的进化过程中形成了对特殊生境——悬崖的适应性,遗传衰退和缺乏适应性不是稀有植物太行花局限分布的原因。在对太行花的保护中应进一步加强对其生境的保护,并在进行迁地保护和回归引种时应兼顾不同变种和地理分布的居群,以实现对其遗传完整性的有效保护。
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根据物种的分布信息结合环境因子估计物种的分布区对珍稀濒危物种的保护有着重要的意义。白豆杉Pseudotaxus chienii为第三纪孑遗植物,我国东南部地区特有,分布区狭窄。本文通过对白豆杉的标本记录研究它的地理分布,找出影响其分布的关键因子并对其潜在分布区进行估计,并解释其分布区形成的原因。全球升温将对物种分布造成重要影响,通过温度升高情况下2100年的气候数据模拟白豆杉未来的潜在分布区,估计温度升高对白豆杉的影响,将对白豆杉的保护有着重要的意义。 根据白豆杉的标本信息结合Diva-Gis软件对白豆杉的地理分布进行研究。以海拔图层和植被图层为底图对白豆杉的分布格局进行研究,并对白豆杉种群的多度进行统计分析。用Diva-Gis软件的气候数据提取功能提取白豆杉分布点的气候信息,并运用主成分分析对影响白豆杉分布的气候因子进行分析,找出影响白豆杉分布的主要环境因子。根据白豆杉的分布信息和气候数据,运用Diva-Gis内嵌的BIOCLIM模型和DOMAIN模型对白豆杉在不同气候条件下的潜在分布区进行估计,评价温度升高对白豆杉分布区的影响。 白豆杉分布格局研究结果表明,白豆杉分布在我国东南部地区中低海拔山区,白豆杉的分布和植被类型及海拔有着密切的关系。白豆杉的分布与海拔的关系表现为,由东到西,分布的最低海拔升高,海拔范围缩小。白豆杉分布地的植被类型为常绿灌木林,常绿阔叶林及针、阔叶混交林。白豆杉由东向西的海拔变化趋势与植被类型的由东向西的海拔变化趋势相一致。PCA分析结果表明白豆杉的分布与温度相关因子有着密切的关系。 现在气候对潜在分布区的估计表明,白豆杉的潜在分布区散布于浙、闽、粤、赣、湘,桂及黔几省各自交界之处即从浙江南部山区沿武夷山山系至南岭山系(向北到沿湘赣交界的罗宵山系)至大瑶山山系(向北沿雪峰山)。潜在分布区南部有三处分布的热点地区,即浙江南部、湖南南部和广西北部地区。三个主要分布区之间仅有有星散的潜在分布区存在,或没有潜在分布区出现,处在一种高度的隔离状态。造成这种潜在分布格局形成的原因可能有二,一是第四纪冰期的到来使白豆杉的分布区向南迁移,局部性气候的变化和地质变化可能导致了部分白豆杉的生境的消失,从而使得原来连续的分布区破碎化,形成了现在的星散分布;二是白豆杉的潜在分布区预测结果与中国东南部地区的山脉走势非常一致,山脉地带小生境多样化能够为白豆杉在垂直地带上的迁移提供更大的可能性。 未来气候数据对白都杉的潜在分布区估计表明,温度升高后白豆杉最适生分布区显著缩小。白豆杉的潜在分布区的地理分布格局发生了明显的变化,原来在南部的适生区明显缩小,星散程度更高。除已知的分布地外,在江西西南部武夷山、南岭山脉的湖南、广西、广东三省交界的地方都是白豆杉的适生区。江西和湖南交界的罗宵山山脉北部到井冈山都有白豆杉分布可能性较大,可以作为野外调查的重点地区。气候变化会使白豆杉在浙江、湖南南部的最适生境破碎化从而影响白豆杉的分布。生境保护对白豆杉的保护起着关键作用。
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保护区是否真的能起保护作用?保护区究竟如何布局?这是自然保护区的建设一直争论不休的课题。就大熊猫保护而言,目前面临的最紧迫问题可能不是保护区数量多少的问题,而是这些多个保护区组成的保护区群的配置或格局是否合理。因此,本研究以岷山大熊猫保护区群为研究对象,分析现有大熊猫及栖息地及其保护现状,指出目前保护区存在的问题,并对岷山大熊猫自然保护区群合理布局提出建议性设计,以期为大熊猫保护及自然保护区建设的理论提供借鉴。 到目前,为了保护大熊猫,在岷山地区已经建立了1 7个自然保护区,这些保护区的建立对大熊猫的保护起到了非常重要的重要。但是,大熊猫栖息地仍然持续下降。就其原因有两方面,即岷山地区人为活动的干扰,如旅游业的盲目发展。但,同时大熊猫自然保护区本身的布局存在一定的不合理性。最后,从景观尺度上提出岷山大熊猫保护区群合理建设的布局,即在分析现有保护布局基础上,找到优先保护的敏感地带建立廊道,将所有保护区连成布局合理的保护区群。 大熊猫受威胁的关键因子并不是竹子,而是森林.竹子复合系统的破碎化或质量的退化,故保护大熊猫应从保护森林、恢复森林.竹子复合生态系统的质量入手。但是,具体实践中究竞采取什么模式来恢复退化的大熊猫栖息地?选取不同模式的科学依据是什么?如何评判不同恢复模式的成本和效益?这些方面的工作到目前缺少系统研究。本研究在分析了岷山地区自然、社会与经济条件的基础上,从荒山荒地造林、天然林保护与低效林地改造主要植被恢复措施着手,全面分析各类植被恢复措施所形成植被的生态效益(保持水土、涵养水源、保持肥力等)、经济收益(木材、果品和林副特产品)、社会效益(种植结构、劳动力再分配等),总结出植被恢复成本和效益的构成要素,计算主要植被恢复模式的成本和效益,为选择适宜的植被恢复措施、典型植被恢复模式和合理确定植被恢复技术提供科学依据,从而推动岷山植被快速健康地恢复,为大熊猫提供适宜的生存空间。 三峡大坝的建设使其固有水域的人为改造导致水位上升,使原本连续的山地生态系统被分割成大小不等的岛屿。水位变化导致的这种生境岛屿化为栖息地破碎化和岛屿生物地理学提供了十分难得的实证研究的机会。然而,同时,这种栖息地的片段化无疑对三峡库区生物多样性保护和生态系统的完整性造成威胁。到目前,为了监测库区建设对生态环境的影响,已经建立了22个定位观测站,但没有一个是生境破碎化方面的,为此建议尽快建立生境破碎化方面的定位研究站。三峡库区生物多样性丰富,但保护区面积仅仅占库区面积的6.9%,而同期我国已经建立了1 999个自然保护区,占国土面积的15%,因此,非常迫切建立更多的保护区(至少达到全国平均水平)。为了从宏观尺度上加强对库区的综合保护,建议从景观生态学的角度出发,将库区作为一个自然、社会和经济复合生态系绕对待。
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In this study, the region corresponding to the Thr-Gly region of the period (per) gene in the Drosophila nasuta subgroup of species was sequenced. The results showed, that this region was highly conserved in the D. nasuta subgroup. There were only nine variable sites found in this 300-bp-long region, all located in two small regions highly variable among Drosophila species. No length variation was observed either within this subgroup or in the Yunnan (YN) population of D. albomicans. The deduced amino acid sequences were identical for all 14 taxa in the D. nasuta subgroup, and a stretch of alternating Thr-Gly pairs was not observed in this subgroup. A phylogenetic tree was constructed. The clustering of some species was in general agreement with previous works, but it also raised some question on the phylogenetic relationship between the nasuta species. The data did not implicate the Thr-Gly region playing a role in behavioral isolation in this subgroup of Drosophila.
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The loss of biodiversity resulting from extinctions is receiving increasing attention. Over several thousands of animal species have been evaluated and recognized as endangered species. Inbreeding depression has been demonstrated in many wild animal speci
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Elevational and latitudinal patterns of species richness for birds and mammals were compared with human population density in relation to nature reserve designation in two areas of Yunnan Province, China. Results suggest that species richness is not the same for the two areas. In Gaoligongshan Region, species richness is inversely correlated with elevation and altitude, while reserve designation is positively correlated with elevation and latitude. In Jingdong County, reserve designations are positively correlated with elevation, but species richness shows no clear trends. In general, the present situation is strongly influenced by human activities. It appears that reserve designation is mismatched with species richness in Gaoligongshan Region, while there is a better fit between the two in Jingdong County. In both areas, however, it appeared that reserves were located primarily in order to reduce conflict with humans rather than to maximize conservation of biodiversity, probably because humans were responsible for forest-especially primary forest-destruction and degradation in the low-lying areas.
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Seven species of the marine enchytraeid genus Grania Southern, 1913 are described from sediments sampled during the 2003 International Workshop on the Marine Flora and Fauna of Esperance Bay and the Recherche Archipelago, on the southern coast of Western Australia. Two species are new to science, the euryhaline Tasmanian G. dolichura Rota and Erseus, 2000 represents a new record for the state, and the remaining four species were known from other parts of Western Australia. Grania quaerens sp. n. is recognized by having a high chaetal index (= 5 short chaetal foot), small coelomocytes, penial apparati with long whip-like terminal stylets, conspicuous spermathecae with ectally bulbous ducts, and ectally granulated ampullae housing sperm rings in their ental region. Grania sperantia sp. n. is readily distinguishable by the complete lack of lateral chaetae, a multiple-banded pattern of the clitellum, extremely long sperm funnels, and the intrasegmental location of the spermathecal pores. The latter new species and four others in the collection (G. bykane Coates, 1990, G. crassiducta Coates, 1990, G. dolichura, and G. ersei Coates, 1990) are remarkable in possessing the head organ, a sensory structure unique to Grania that was not noted previously in Western Australian species. When considering the whole genus, the geographic pattern of the head organ appears southern-centred: of the 17 species of Grania reported to possess it, as many as 13 inhabit the southern latitudes. The seventh species of the Esperance collection, G. vacivasa Coates and Stacey, 1993, is notable for the kind of items found in its gut and the unusual appearance of its pygidium.
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The largest damming project to date, the Three Gorges Dam has been built along the Yangtze River (China), the most species-rich river in the Palearctic region. Among 162 species of fish inhabiting the main channel of the upper Yangtze, 44 are endemic and are therefore under serious threat of global extinction from the dam. Accordingly, it is urgently necessary to develop strategies to minimize the impacts of the drastic environmental changes associated with the dam. We sought to identify potential reserves for the endemic species among the 17 tributaries in the upper Yangtze, based on presence/absence data for the 44 endemic species. Potential reserves for the endemic species were identified by characterizing the distribution patterns of endemic species with an adaptive learning algorithm called a "self-organizing map" (SOM). Using this method, we also predicted occurrence probabilities of species in potential reserves based on the distribution patterns of communities. Considering both SOM model results and actual knowledge of the biology of the considered species, our results suggested that 24 species may survive in the tributaries, 14 have an uncertain future, and 6 have a high probability of becoming extinct after dam filling.