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81.
Sampling adequacy in an extreme environment: species richness patterns in Slovenian caves 总被引:1,自引:0,他引:1
David C. Culver Mary C. Christman Boris Sket Peter Trontelj 《Biodiversity and Conservation》2004,13(6):1209-1229
Caves harbor a rich fauna unique to subterranean environments. Although extensive records of cave animals are available, only a small fraction of known caves in any region have been biologically assessed. We investigated the impact of incomplete sampling using one of the richest, best documented cave faunas in the world – that of the Dinaric karst of Slovenia. We utilized time snapshots (1940, 1970, and 2000) of the caves and cave fauna to analyze stability of hotspots, spatial pattern, and relationship between number of species and number of caves. Using data aggregated into 100km2 hexagons, the location of hotspots, black–white joins, Moran's I, and spatial autocorrelation all remained constant, at least from 1970 on. The linear regression coefficient of the relationship between number of caves and number of species declined with time. Most hexagons had been sampled, but there was no indication that any hexagon had been sampled intensively enough for the accumulation curve of number of caves versus number of species within a hexagon to reach an asymptote. This appeared to be the result of a highly skewed distribution of species richness among caves. Number and position of hotspots can be predicted from information on these few high diversity caves. 相似文献
82.
中国夜蛾科昆虫区系初步研究(鳞翅目:双孔亚目) 总被引:5,自引:0,他引:5
对我国分布记载较详细的1410种夜蛾科昆虫区系分析结果表明:1)在世界昆虫区系中,可分为17个分布型,以东洋界种类最多,占35.6%;古北界种类居第二,占33.0%;古北界和东洋界共有种类居第三,占23.0%。2)中国夜蛾科昆虫主要由古北界种类、东洋界种类、古北界和东洋界共有种类组成,占总数的91.7%;与澳洲界共有67种,占4.8%;与非洲界共有51种,占3.6%;与新北界共有23种,占1.6% 相似文献
83.
重庆机场草地土壤动物群落特征及其与鸟类关系的初步研究 总被引:14,自引:0,他引:14
对重庆机场草地土壤动物群落的组成,结构和时空动态特征进行了比较研究,初步分析了土壤动物与机场鸟类在种类和数量上的动态关系。结果表明:土壤动物的优势类群为蜱螨目;常见类群多为大,中型土壤动物,是鸟类捕食的主要对象;活动性弱的小型土壤动物是幼虫主要分布在土壤和腐质层中,且群落的多样性和稳定性较高; 相似文献
84.
Katrin Böhning-Gaese Laura I. González-Guzmán James H. Brown 《Evolutionary ecology》1998,12(7):767-783
One could predict that the capacity for travelling great distances might predispose long-distance migratory birds to be good colonists and to exhibit wider geographic distributions than their non-migratory or short-distance migratory relatives or non-volant mammals. This prediction is not supported by the data on avian biogeography. The distributions of species, genera and families of North American and Eurasian birds and mammals are indeed related to migratory status, but long-distance migratory birds exhibit a great deal of biogeographic regionalism. In particular, at all taxonomic levels their distributions tend to be confined to either the Eastern or Western Hemisphere, suggesting that there has been little successful east–west dispersal between North America and Eurasia. Compared to non-migratory birds, short-distance migratory birds and non-volant mammals, long-distance migrants appear to be subject to severe constraints on their physiology, behaviour and ecology, w hich have prevented colonization of distant regions. 相似文献
85.
Abstract. 1. Euedaphic collembola alter their soil distribution in response to above‐ground aphid herbivory of Poa annua L. Graminae, a host grass. 2. Two mechanisms potentially underpin this effect. Carbon‐rich aphid honeydew falling onto the soil surface may affect mycophagous collembola; alternatively aphid‐induced changes in root biomass may be necessary to produce changes in collembola abundance. 3. When compared to a plant‐only control, aphid herbivory increased the number of collembola in the top 5 cm of soil, reduced both foliar and root biomass, and increased shoot/root ratio. Honeydew addition had no effect on collembola numbers or any recorded host‐plant parameter. 4. Honeydew deposition is not responsible for the increased numbers of collembola found in the upper soil after aphid herbivory; aphid‐induced reductions in root biomass may be the most important factor explaining knock‐on effects of aphid herbivory on soil fauna. 相似文献
86.
Distribution, endemism and threat status of freshwater fishes in the Western Ghats of India 总被引:4,自引:0,他引:4
Aim To study (1) the large-scale distribution patterns of freshwater fishes in the Western Ghats of India; (2) the endemism and uniqueness of the fishes in various zones; and (3) the threat status of fishes by categorizing them under low risk (LR), vulnerable (VU), endangered (EN) and critically endangered (CR). Location The Western Ghats of India. Methods The scientific literature describing the freshwater fishes of the Western Ghats was reviewed. Data describing the lists of the species were extracted and complied. The species accumulation curve was plotted using Michaelis–Menten-like equation. The Western Ghats was divided into six zones and similarity of the species was calculated using Jacquard's index. Results Literature to date records 288 species belonging to 12 orders, 41 families and 109 genera, of which 118 species are endemic and 51 are unique. However, the species accumulation curve shows that there might be 345 species in this region, indicating that 16% species have not been recorded to date. An analysis of the distribution pattern of fishes in the Western Ghats suggests that the southern region is more diverse than the northern and central regions. The southern region shows high endemism and high uniqueness while the northern region shows high endemism but less uniqueness. The similarity index between the zones indicates that as the distance between the zones increases similarity decreases. The status of 105 of 288 species was not known due to data deficiency but among the remaining 183 species, 58 species were categorized as LR, 41 as VU, 54 as EN, 24 as CR while the remaining six species were introduced. Conclusions The distribution patterns of fishes in the Western Ghats are discussed in accordance with the geography of Western Ghats, its climatic conditions and ‘Satpura Hypothesis’. The threat status of fishes found in Western Ghats suggests that at least 41% of fish fauna is threatened by either being VU, EN or CR. Implication of potent conservation measures is necessary to conserve the fish fauna of Western Ghats. 相似文献
87.
对新疆蛾类标本鉴定和资料整理,共得到蛾类12科245属549种。其中种类最多的是夜蛾科Noctuidae136属364种,物种数量超过20种的分别有卷蛾科Tortricidae 24属36种,天蛾科Sphingidae 13属30种,灯蛾科Arctiidae 19属25种和木蠹蛾科Cossidae 8属25种;物种数超过10种的有尺蛾科Geometridae 13属18种,螟蛾科Pyralidae 14属17种和舟蛾科Notodontidae 8属17种;其余几个科种类均少于10种。在世界动物地理中,新疆蛾类以古北界为主,种数占到了434种(79.05%),其他动物地理区划组成类型仅115种(20.95%)。属级区系类型与种级基本一致,古北界162种,占总数的66.12%;古北界+东洋界共有58属,占23.67%,两种分布型占总数的89.79%。在中国动物地理中,新疆蛾类与蒙新区关系最为密切,共计245种(44.63%),其次是蒙新与华北共有56种(10.20%),蒙新与青藏共有52种(9.47%),其他动物区系组成较少。属级的区系类型以蒙新区为主,与同处古北界的东北区、华北区和青藏区关系最为密切。 相似文献
88.
1. The freshwater crayfish Cherax dispar (Decapoda: Parastacidae) inhabits coastal regions and islands of South East Queensland, Australia. We hypothesised that populations of C. dispar on different islands would be more genetically divergent from each other than populations from different drainages within the same island or on the mainland. 2. Phylogenetic and phylogeographic analyses were conducted on two mitochondrial genes (cytochrome oxidase subunit I & 16S ribosomal DNA) and one nuclear gene (Internal Transcribed Spacer region 2). Phylogeographic patterns were compared with those for other freshwater organisms in the area. 3. Deep genetic divergences were found within C. dispar, including four highly divergent (up to 20%) clades. The geographic distribution of each of the clades revealed strong latitudinal structuring along the coast rather than structuring among the islands. The high genetic divergence observed among the C. dispar clades was estimated to have pre‐dated island formation and may represent ancient river drainage patterns. 4. A restricted distribution was observed for the most divergent clade, which was discovered only on two of the sand islands (North Stradbroke Island and Moreton Island). Furthermore, strong phylogeographic structuring was observed within this clade on North Stradbroke Island, where no haplotypes were shared between samples from opposite sides of the island. This low connectivity within the island supports the idea that C. dispar rarely disperse terrestrially (i.e. across watersheds). 相似文献
89.
Summary We propose a Bayesian dose‐finding design that accounts for two important factors, the severity of toxicity and heterogeneity in patients' susceptibility to toxicity. We consider toxicity outcomes with various levels of severity and define appropriate scores for these severity levels. We then use a multinomial‐likelihood function and a Dirichlet prior to model the probabilities of these toxicity scores at each dose, and characterize the overall toxicity using an average toxicity score (ATS) parameter. To address the issue of heterogeneity in patients' susceptibility to toxicity, we categorize patients into different risk groups based on their susceptibility. A Bayesian isotonic transformation is applied to induce an order‐restricted posterior inference on the ATS. We demonstrate the performance of the proposed dose‐finding design using simulations based on a clinical trial in multiple myeloma. 相似文献
90.
长期施肥对黄淮海平原农田中小型土壤节肢动物的影响 总被引:4,自引:1,他引:3
在2008年9月和2009年2月,采用改良干漏斗方法(Modified Tullgren)对黄淮海地区长期定位施肥试验下中小型土壤节肢动物进行调查。试验包括氮磷钾(NPK)、氮磷(NP)、氮钾(NK)、磷钾(PK)、有机肥(OM)、1∶1化学氮肥与有机氮肥(OMNPK)和不施肥(CK)7个处理。结果表明:OM和OMNPK处理有利于提高土壤动物丰富度和多样性;NK处理不利于土壤动物的生存和发展,缺磷影响了土壤动物数量的增长;从优势类群弹尾目和蜱螨目来看,OM和OMNPK处理对弹尾目等节跳科、棘跳科和球角跳科的生长有利,而圆跳科在NPK处理下具有更高的数量;OMNPK处理对蜱螨目中气门亚目有显著的正效应,对前气门亚目和甲螨亚目也有一定的正向作用;氮肥对弹尾目没有表现出正相关关系,但在一定程度上增加了蜱螨目的数量。 相似文献