关键词： 疾病动物模型   树鼩   亚热带地区   亚洲东南部   啮齿类动物   哺乳动物   大体解剖   新陈代谢   发病机理   灵长类  

摘要： 树鼩(tupaia,tree shrew)是最低等的灵长类哺乳动物,主要分布于亚洲东南部的热带和亚热带地区.由于具有体小、比较容易饲养、价廉及新陈代谢和大体解剖远比啮齿类动物更接近人类等优点,树鼩已广泛用于病毒、细菌、寄生虫和神经、内分泌、泌尿、肿瘤等方面的研究.疾病动物模型为研究疾病的发病机理、治疗及防治提供了平台.本文对树鼩作为疾病动物模型的研究作一概述.

关键词： HURRICANES   TREE islands   FOREST canopy gaps   EXOTIC plants   ARTHUR R. Marshall Loxahatchee National Wildlife Refuge (Fla.)  

摘要： Tree islands-small, wetland forest communities imbedded in a matrix of freshwater marsh-characterize Arthur R. Marshall Loxahatchee National Wildlife Refuge in South Florida. The establishment and spread of invasive exotic plant species were hypothesized to alter tree-island communities and prolong recovery times from hurricane disturbances. During the fall of 2004, two hurricanes, Frances and Jeanne, caused damage to these tree islands. We examined the spatial extent of damage to tree islands and tree species across the Refuge by sampling 74 islands. Each tree island was assigned an overall damage rating based on both the openness of the canopy and the type and quantity of damage received. Distance from the eye-wall of the hurricanes, tree-island size, average tree height on the island, and relative abundance of invasive exotic plants were examined as predictors of damage. Over 85% of the sampled tree islands had damage, with most of the damage occurring in the center of the Refuge. Most tree islands were found to have moderate damage, (i.e., snapped large branches and less than 50% canopy cover removed). Persea palustris (swamp bays) had more snapped trunks than Ilex cassine (dahoon holly) and Myrica cerifera (wax myrtle). Islands with larger trees had heavier damage than islands with shrubs or smaller trees. Fifty-eight percent of the tree islands sampled had either Lygodium microphyllum (lygodium) and/or Melaleuca quinquenervia (melaleuca). The only island with severe damage had abundant lygodium that appeared to have caused the entire canopy to collapse. These hurricanes present a unique opportunity to investigate recovery patterns of tree islands in an ecosystem impacted by invasive exotics. They also provide an opportunity to examine patterns of spread and recruitment of lygodium and melaleuca.

关键词： 随机广义Cookie-Cutter集   弱收敛   紧测度   记忆函数   系统发育树   线粒体完全基因组   傅立叶变换   Kullback-Leibler散度距离  

摘要： 我们首先在构造随机广义Cookie-Cutter集的过程中，通过记忆函数，研究了这种随机概率测度序列的紧测度的收敛性。方法是首先构造了[0，T]上的随机广义Cookie-Cutter集KT。令K_n为构造KT中的第n级集合，并在K_n上定义记忆函数。基于这个记忆函数，我们定义了K_n上的随机概率测度φ_n（Υ）。令Ψ_n（·）=Eφ_n（·），其中Ψ_n为随机测度φ_n的紧测度。最后证明了序列Ψ_n是弱收敛的且有Ψ=limΨ_n。 对生物信息问题的研究，我们主要是不通过序列比对，讨论64种脊椎动物的线粒体完全基因组之间的联系，用快速的傅立叶变换（FFT）作用于由蛋白质序列得到的组分向量，然后计算Kullback-Leibler散度距离，用PHYLIP软件包中的NJ（neighbour-joining）方法构造发育树。从系统发育树可以看出这64种线粒体基因组可以被分为两大部分。一部分是哺乳动物，另一部分包含两个子部分，分别是鱼类和古生物类（包括鸟类和爬行类）。由此建立的树的拓扑结构在很大程度上与已有的脊椎动物的系统发育树是吻合的。

关键词： 作品集   现代   动画   连环画   中国  

ISBN: (纸本)7802200520

摘要： 本书由四个独立小故事配以大幅彩图组成的经典动物童话合集。

关键词： Joshua tree   scatter hoarding   seed caching   seed dispersal   Yucca brevifolia  

摘要： Joshua tree (Yucca brevifolia) is a distinctive and charismatic plant of the Mojave Desert. Although floral biology and seed production of Joshua tree and other yuccas are well understood, the fate of Joshua tree seeds has never been studied. We tested the hypothesis that Joshua tree seeds are dispersed by seed-caching rodents. We radioactively labelled Joshua tree seeds and followed their fates at five source plants in Potosi Wash, Clark County, Nevada, USA. Rodents made a mean of 30.6 caches, usually within 30 in of the base of source plants. Caches contained a mean of 5.2 seeds buried 3-30 mm deep. A variety of rodent species appears to have prepared the caches. Three of the 83 6 Joshua tree seeds (0.4%) cached germinated the following spring. Seed germination using rodent exclosures was nearly 15%. More than 82% of seeds in open plots were removed by granivores, and neither microsite nor supplemental water significantly affected germination. Joshua tree produces seeds in indehiscent pods or capsules, which rodents dismantle to harvest seeds. Because there is no other known means of seed dispersal, it is possible that the Joshua tree-rodent seed dispersal interaction is an obligate mutualism for the plant.

关键词： Ghana   hunting   duality   sustainability   bushmeat   livelihoods  

摘要： This article argues that insufficient attention has been paid in the recent literature to the social and environmental factors which regulate hunting in Ghanaian savannas, and to how this may influence the sustainability of their livelihoods. Despite the vital significance of this issue, the emphasis in the literature and media has been on the destructive impacts of hunting and the bushmeat trade on wildlife. Taking a case study from the coastal savanna of Ghana, a region commonly regarded as a degraded relict of former deciduous forest with a richer wildlife past, it investigates the hypothesis that structure/actor dualities, manifested by socio-cultural change, local environmental knowledge and livelihood activity options, are the primary regulators of hunting intensity and possible sustainability. Such an evaluation is effective if done from a structuration perspective. The integrated methodology incorporates social surveys, GIS based time series image analysis, ecological field methods and statistical analysis. The results provide evidence that the direct and indirect regulatory functions of the socioenvironmental context provide a core feature of the sustainability of hunting. It is concluded that local strategies of resource management may provide an effective complement to conservation policy. (c) 2005 Elsevier Ltd. All rights reserved.

关键词： ants   Batesian mimicry   staphylinid beetle   predation  

摘要： Some myrmecophilous animals show myrmecomorphy, however, its adaptive significance is still controversial. We investigated a possible benefit of Batesianmimicry between a myrmecophilous staphylinid beetle, Pella comes, and its host ant, Lasius (Dendrolasius) spathepus, by using a common ant predator, the Japanese treefrog, Hyla japonica. In the field, H. japonica were found to feed on numerous ants and other insects, but in laboratory experiments they refused feeding on L. spathepus. L. spathepus was highly repellent to these frogs, while P. comes was potentially palatable. After repeated contacts with L. spathepus which led to its avoidance the treefrogs started to reject P. comes as well . This suggests that myrmecomorphy is beneficial to P. comes, reducing the risk of predation, and that it , may represent a case of Batesian mimicry. may represent a case of Batesian mimicry.

关键词： C : N : P ratio   floods   invertebrate   litter quality   Populus   Rio Grande   riparian vegetation   river floodplain  

摘要： 1. We examined the role of flooding on the leaf nutrient content of riparian trees by comparing the carbon : nitrogen : phosphorus (C : N : P) ratio of leaves and litter of Rio Grande cottonwood (Populus deltoides ssp. wislizenii) in flood and non-flood sites along the Middle Rio Grande, NM, U.S.A. The leaf C : N : P ratio was also examined for two non-native trees, saltcedar (Tamarix chinensis) and Russian olive (Elaeagnus angustifolia), and six species of dominant riparian arthropods. 2. Living leaves and leaf litter of cottonwoods at flood sites had a significantly lower leaf N : P ratio and higher %P compared with leaves and litter at non-flood sites. A non-flood site downstream from wastewater effluent had a significantly lower litter C : N ratio than all other sites, suggesting N fertilisation through ground water. The non-native trees, saltcedar and Russian olive, had higher mean leaf N content, N : P ratio, and lower C : N ratio compared with cottonwoods across study sites. 3. Riparian arthropods ranged from 5.2 to 7.1 for C : N ratio, 56-216 for C : P ratio, and 8.9-34 for N : P ratio. C content ranged from 25 to 52% of dry mass, N content from 4.7 to 10.8%, and P content from 0.59 to 1.2%. Differences in stoichiometry between high C : nutrient leaf litter and low C : nutrient invertebrates suggests possible food-quality constraints for detritivores. 4. These results suggest that spatial and temporal variation in the C : N : P ratio of cottonwood leaves and leaf litter is influenced by surface and subsurface hydrologic connection within the floodplain. Reach-scale variation in the elemental composition of riparian organic matter inputs may have important implications for decomposition, nutrient cycling, and food webs in river floodplain systems.

关键词： water management   wildlife management   semi-arid savannas   artificial water sources   water source heterogeneity   rainfall   Kruger National Park  

摘要： Savanna water management is predicated on the hypothesis that surface water availability can be manipulated at scales that influence herbivore distributions. Using a case study in the Kruger National Park, South Africa, we assess the contribution of perennial and ephemeral water sources to surface water availability in the dry season. We posit that surface water availability in savanna ecosystems exists along a continuum of being determined primarily by perennial or ephemeral water sources and propose that locating an ecosystem along this continuum provides a means to evaluate the utility of water management. We also develop general hypotheses about the relative response of herbivore species to ephemeral water sources. (c) 2005 Elsevier Ltd. All rights reserved.

关键词： Chile   climbing ability   habitat use   marsupial   rodent   small mammal  

摘要： Climbing ability can be a major component of the capability of terrestrial mammals to use vertical habitats. Previous studies Suggest that small mammals from central Chile have low climbing capabilities. However, those Studies have not disentanaled the influence of tree diameter in natural habitats from true climbing ability of different species. We carried Out a laboratory experiment by Studying the climbing ability of 4 central Chilean small mammals, 2 octodontid rodents (Octodon bridgesi and O. degus), I murid rodent (Phyllotis darwini), and I marsupial (Thylamys elegans), in situations with different stern diameters. Species showed distinctive climbing abilities. The marsupial T. elegans showed efficient climbing ability independent of stem diameter. P. darwini and O. bridgesi were both influenced by stein diameter, but the former species used smaller-diameter stems less frequently. O. degus showed the lowest climbing ability.