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161.
中国种子植物特有属的分布区学研究 总被引:12,自引:0,他引:12
本文讨论了分布区的概念和分布区周界的划定方法,认为邻近距离平均法(mean propinquity method)对划定分布区的周界具有较大的科学性和可用性。根据247幅中国种子植物特有属的分布区图及其属内各种在属分布区范围内的分布情况,我们将中国种子植物特有属划分为5个分布区类型。本文还对中国种子植物特有属分布区与地形和气候条件的关系,以及与植被和植物区系界线的关系进行了分析,提出制约分布区形状和大小的主要决定因素,并指出种在属分布区内的分布规律的研究对次一级植物区系分区或植被区划研究具有重要意义。 相似文献
162.
163.
川,滇蚱科的新属和新种:(直翅目:蚱科) 总被引:7,自引:1,他引:6
本文记载采自四川、云南二省蚱科2新属3新种。驼背蚱属Gibbotettix,新属,近似于Cladonotella Hanc.及Potua Bol.,其区别于后两属为前胸背板后突顶端平截,中央略凹;触角细长,中段节长为宽的7~9倍。峨嵋驼背蚱Gibbotettix emeiensis,新种,体暗褐色。红河驼背蚱G.hongheensis,新种,近似于峨嵋驼背蚱G.emeiensi,主要区别为头顶宽为一眼宽的2倍;头顶侧缘隆线明显片状突出;触角着生于眼下缘之下不远;前胸背板前缘平截;背板驼背向后渐低。二齿蚱属Bidentatettix,新属,近似于Falconis Bol.,其区别为头顶前缘具2向前的锐齿;前胸背板侧片后角具5个锐齿;各足股节下、上缘均具1列大刺突。云南二齿蚱B.yunnanensis,新种,体暗黄褐色。 相似文献
164.
樟科木姜子属群的起源与演化 总被引:6,自引:3,他引:3
论述了樟科木姜子属群的起源与演化,认为该属群起源于古北大陆南部和古南大陆北部,以及古地中海周围热带地区,起源时间不早于中白垩纪。这一自然属群明显存在着平行进化情况,其核心的木姜子属和山胡椒属极可能是同地起源于共同祖先,我国南部至印度马来西亚可能是这两属的起源和分化中心,并从这里向热带美洲及大洋洲扩散。其余的属可能从这一核心演化出来。 相似文献
165.
Many microorganisms are capable of producing and secreting exopolysaccharides (EPS), which have important implications in medical fields, food applications or in the replacement of petro-based chemicals. We describe an analytical platform to be automated on a liquid handling system that allows the fast and reliable analysis of the type and the amount of EPS produced by microorganisms. It enables the user to identify novel natural microbial exopolysaccharide producers and to analyze the carbohydrate fingerprint of the corresponding polymers within one day in high-throughput (HT). Using this platform, strain collections as well as libraries of strain variants that might be obtained in engineering approaches can be screened. The platform has a modular setup, which allows a separation of the protocol into two major parts. First, there is an automated screening system, which combines different polysaccharide detection modules: a semi-quantitative analysis of viscosity formation via a centrifugation step, an analysis of polymer formation via alcohol precipitation and the determination of the total carbohydrate content via a phenol-sulfuric-acid transformation. Here, it is possible to screen up to 384 strains per run. The second part provides a detailed monosaccharide analysis for all the selected EPS producers identified in the first part by combining two essential modules: the analysis of the complete monomer composition via ultra-high performance liquid chromatography coupled with ultra violet and electrospray ionization ion trap detection (UHPLC-UV-ESI-MS) and the determination of pyruvate as a polymer substituent (presence of pyruvate ketal) via enzymatic oxidation that is coupled to a color formation. All the analytical modules of this screening platform can be combined in different ways and adjusted to individual requirements. Additionally, they can all be handled manually or performed with a liquid handling system. Thereby, the screening platform enables a huge flexibility in order to identify various EPS. 相似文献
166.
Little data exist on the bacterial flora of the cotton boll weevil, Anthonomus grandis, which is a common insect pest to cotton farmers in the United States. This investigation determined the total numbers of aerobic and anaerobic bacteria in diapausing field-collected boll weevils and active adult laboratory-reared boll weevils. Identifications were made of aerobic genera isolated from field-collected and laboratory-reared boll weevils that had previously been surface sterilized. The genera found, in order of decreasing frequency, in the field-collected boll weevils were Lactobacillus, Erwinia, Flavobacterium, Enterobacter, and Pseudomonas. The genera found, in order of decreasing frequency, in the laboratory-reared boll weevils were Lactobacillus, Pseudomonas, Streptococcus, Erwinia, Enterobacter, and Flavobacterium, Lactobacillus was the most frequently found genus in both groups. 相似文献
167.
REN Dond 《Insect Science》2002,9(4):53-67
Abstract A new family, Grammolingiidae of fossil lacewings is erected, of which 3 new genera and 6 new species are described and illustrated: Grammolingia boi . gen. nov. et sp. nov., Lithlingia rhra gen. nov. et sp. nov., Litholingia eumopha gen. nov. et sp. nov. and Litholingiu polychotom gen. nov. et sp. nov., Leptolingia jurassica gen. nov. et sp. nov. and Leptolingia tianyiensis gen. noc. et sp. nov. A key to genera within this new family is provided. All specimens described were collected from the Middle Jurassic Jiulongshan Formation of Eastern Inner Mongolia, China. The present discovery demonstrates that present knowledge of the Jurassic Neuropetra fauna remains very poor. The fossil specimens are deposited in Yizhou Fossil Museum and Department of Biology, Capital Normal University, respectively. 相似文献
168.
Knowing the geographic extents of species is crucial for understanding the causes of diversity distributions and modes of speciation and extinction. Species geographic ranges are often viewed as approximately constant in size in geological time, even though climate change studies have shown that historical and modern species geographic distributions are not static. Here, we use an extensive global microfossil database to explore the temporal trajectories of geographic extents over the entire lifespan of marine nannoplankton, diatom, planktic foraminifer and radiolarian species. We show that geographic extents are not static over geological time-scales. Temporal trajectories of species geographic ranges are asymmetric: the rise is quicker than the fall. We propose that once a species has overcome its initial difficulties in geographic establishment, it rises to its peak geographic extent. However, once this peak value is reached, it will also have a maximal number of species to interact with. The negative of these biotic interactions could then cause a gradual geographic decline. We discuss the multiple implications of our findings with reference to macroecological and macroevolutionary studies. 相似文献
169.
本文报道中国■目昆虫■科Phasmatidae与异■科Heteronemiidae各1新纪录属:叶尾■属ACro-phylla Gray和副厚■属Parapachymorpha Brunner;及其各1新种:四川叶尾■Acrophylla sichuanensis,sp.nov.和四刺副厚■Parapachymorpha tetracantha,sp.nov.模式标本保存于西北农业大学昆虫标本馆。 相似文献
170.
L. Katinas 《Plant Systematics and Evolution》2000,223(3-4):229-250
Adenocaulon andEriachaenium are two problematic genera because their tribal and subfamilial placement in Asteraceae is uncertain. Previous cladistic analyses based on molecular data undertaken to analyze the relationships within Asteraceae, placeAdenocaulon in the tribe Mutisieae (Cichorioideae). This paper investigates cladistic relationships amongAdenocaulon andEriachaenium and tribes of subfamilies Cichorioideae and Asteroideae using morphological data. Thirty-eight characters were scored across 52 genera selected as exemplar taxa to represent the current classification system. In the analysis (one tree, length = 86, c.i. = 0.55, r.i. = 0.64)Adenocaulon andEriachaenium are sister taxa and appear as an isolated clade nested in Cichorioideae. A new, tentative position among the tribes of the paraphyletic Cichorioideae is proposed for these two isolated genera. 相似文献