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1.
布氏田鼠种群生态及行为生态学研究进展尹峰房继明(北京师范大学生物学系,100875)ResearchAdvancesinPopulationEcologyandBehavioralEcologyofBrandt’sVoles(Microtusbran...  相似文献   

2.
植物对重金属的耐性机理   总被引:62,自引:3,他引:62  
植物对重金属的耐性机理杨居荣,黄翌(北京师范大学环境科学研究所,100875)MechanismofHeavyMetalToleranceofPlants.¥YangJurong;HuangYi(InstituteofEnviron-mentalSc...  相似文献   

3.
计算机模拟在群体遗传教学中的应用   总被引:2,自引:2,他引:0  
黄远樟 《遗传》1998,20(4):26-31
计算机模拟在群体遗传教学中的应用黄远樟(北京师范大学生物学系,北京100875)TheApplicationofComputerSimulationinTeachingPopulationGeneticsHUANGYuanzhang(Departme...  相似文献   

4.
模糊向量一Markov转移矩阵法在生态影响评价中的应用毛显强,杨居荣(北京师范大学环境科学研究所100875)TheMethodorFuzzyVector一MarkovTransferMatrixandItsUseinEcologicallml,ac...  相似文献   

5.
DUD法拟合生态学中的非线性模型   总被引:4,自引:0,他引:4  
DUD法拟合生态学中的非线性模型*李仲来(北京师范大学数学系,100875)FitingNonlinearModelsofEcologywithDudAlgorithm.LiZhonglai(DepartmentofMath.,BeijingNorm...  相似文献   

6.
蕨精细胞的发育及其超微结构刘宁,方瑾,周云龙,郑江霞,陈令静(北京师范大学生物系,北京100875)蕨(Pteridiumaquitinumvar,latiusculum)成熟精细胞螺旋形,有大量的鞭毛形成,释放前,存在于蕨原叶体的精子器中。精子器球...  相似文献   

7.
蕨游动精子的扫描电镜观察周云龙,刘宁,方瑾,杜圣兵,陈令静(北京师范大学生物系,北京100875)蕨(Pterldiumaquilinumvar,latiuscuIum)属蕨科,蕨属。将其成熟孢子用5%砍氯酸钠消毒后在无菌条件下接种于琼脂培养基上培养...  相似文献   

8.
不同蔗糟浓度对蕨精子器释放精子的影响周云龙,方瑾,刘宁,陈令静(北京师范大学生物系,北京100875)蕨(Pteridiumaquilinumvar.latiusculum)属蕨科,蕨属。从同一个培养瓶中取出用蔗时孢子培养的具成熟精子器的原叶体,将其...  相似文献   

9.
布氏田鼠冷习服过程中的适应性产热特征侯建军李庆芬黄晨西(北京师范大学生物学系北京100875)关键词布氏田鼠适应性产热环磷酸腺苷钠、钾ATP酶T4-5′脱碘酶将内蒙草原上捕捉的布氏田鼠(Microtusbrandti)随机分组(体重在35-40g...  相似文献   

10.
啮齿动物的空间分布格局   总被引:10,自引:0,他引:10  
啮齿动物的空间分布格局房继明(北京师范大学生物学系,100875)SpatialDistributionPatternsofRodents.¥FangJiming(DepartmentofBiology,BeijingNor-malUniversit...  相似文献   

11.
Phylogenetic definitions and taxonomic philosophy   总被引:4,自引:0,他引:4  
An examination of the post-Darwinian history of biological taxonomy reveals an implicit assumption that the definitions of taxon names consist of lists of organismal traits. That assumption represents a failure to grant the concept of evolution a central role in taxonomy, and it causes conflicts between traditional methods of defining taxon names and evolutionary concepts of taxa. Phylogenetic definitions of taxon names (de Queiroz and Gauthier 1990) grant the concept of common ancestry a central role in the definitions of taxon names and thus constitute an important step in the development of phylogenetic taxonomy. By treating phylogenetic relationships rather than organismal traits as necessary and sufficient properties, phylogenetic definitions remove conflicts between the definitions of taxon names and evolutionary concepts of taxa. The general method of definition represented by phylogenetic definitions of clade names can be applied to the names of other kinds of composite wholes, including populations and biological species. That the names of individuals (composite wholes) can be defined in terms of necessary and sufficient properties provides the foundation for a synthesis of seemingly incompatible positions held by contemporary individualists and essentialists concerning the nature of taxa and the definitions of taxon names.  相似文献   

12.
The fossil record of bryophytes is generally poor and infertile plants attributable to liverworts and mosses could also be thalloid vascular plant gametophytes or herbaceous lycophytes respectively. The paucity of the bryophytic record could be the result of relatively rapid degradation of bryophytic material in comparison to that of vascular plants, the absence of lignified cells in bryophytes sustaining this belief. However, certain organs of bryophytes are as robust as those of vascular plants (e.g. spores) and the hydroxybenzofuran polymers produced by some mosses could be of similar preservational resistance to lignins. A simplistic experiment to test the relative resistance to decay of bryophytic material has been undertaken. Its findings suggest that bryophytic plant material has a similar preservational potential to that of a selected vascular plant, particularly in organic rich sediments. This result may be construed to imply that bryophytes were indeed less abundant in the preservational environments of the Coal Measures than might be expected on the basis of current palaeoenvironmental reconstructions.  相似文献   

13.
Research on the influence of sea level variations on the benthic faunas have been carried out in the Upper Ordovician of Sardinia. Study of the depositional facies and sequence analysis of the upper part (Lower Ashgill) of the Portixeddu Formation led to the identification of the sedimentary environments. Cystoids and crinoids are associated to bryozoans and brachiopods in most levels. The numerical analysis of associations and megaguilds shows that crinoids and cystoids have a higher frequency in the proximal and median facies of the upper offshore. The columnal association characterized by Conspectocrinus celticus and the coronoid Mespilocystites tregarvanicus has been discovered in the upper part of the formation. This material and complementary samples from Upper Ordovician of Sardinia and Kabylia (Algeria) bring additional data on the systematic and show the wide distribution of this fauna outside of the Ibero-armorican domain. The distribution of this echinoderm association supports a palaeogeographical position of the Ibero-armorican domain and Sardinia within the north gondwanan margin during the Lower Palaeozoic.  相似文献   

14.
Found in Chiapas (South-East of Mexico), Praealveolina michaudi nov. sp. and Chubbina jamaicensis (of Campanian-Maestrichtian age) are described, both evolved from Nummoloculina sp. while Raadshoovenia guatemalensis (upper Paleocene-lower Eocene) arises from Quinqueloculina. We precisely analyze and modelize the nepionic coiling during the evolutionary change from Miliolacea to Alveolinacea. During ontogenesis as well as during phylogenesis, quinqueloculine coiling progresses to streptospiral and then to planispiral chamber arrangement with the increase of volume of embryo and of chambers. Appearance of these large foraminifers are understood as a consequence of the rise of K-strategies in their mode of life, following the development of photosynthetic symbioses.  相似文献   

15.
突变文库的构建是定向进化研究过程中一个关键步骤,主要利用天然存在的系统或者人工合成的分子技术来产生多样性核酸分子文库,为制备和筛选具有一定特性的蛋白酶、多肽、人工抗体等提供庞大的遗传基因库,也可用于合成生物学中相关基因元件的研究与筛选,为目标生物制品的高效工业化生产提供动力。随着对突变文库构建技术研究的日益深入,各种文库构建策略相继被开发出来,并在生物能源、生物化工、生物医药、生物试剂和食品工业等方面得到了广泛的应用。然而,定向进化中的文库构建策略多有不同,各种突变文库构建技术的核心方法也在不断创新。主要介绍近年来实验室中人工合成多样性文库的前沿技术,并对文库构建技术在自动化和智能化方向的发展进行了展望。  相似文献   

16.
A phylogenetic analysis of 123 morphological characters of basal waterfowl (Aves: Anseriformes) and other selected avian orders confirmed that the screamers (Anhimae: Anhitn-idae) are the sister-group of other waterfowl (Anseres), and that the magpie goose (Anseranatidae: Anseranas semipalmata) is the sister group of other modern waterfowl exclusive of screamers (Anatidae sensu stricto). The analysis also supports the traditional hypothesis of the gallinaceous birds (Galliformes) as the sister group of the Anseriformes. Presbyornis, a fossil from the early Eocene of Wyoming and averred by Olson & Feduccia as showing that the Anseriformes were derived from shorebirds (Charadriiformes), was found to represent the sister group of the Anatidae. Associated hypotheses by Olson & Feduccia concerning the implications of Presbyornis for the phylogenetic relationships of flamingos (Phoenicopteriformes), the position of the Anhimidae within the waterfowl, relationships among modern Anatidae, and a plausible evolutionary scenario for waterfowl also are rejected. Analyses revealed that cranial characters were critical to the establishment of the Galliformes as the sister group of the Anseriformes; exclusion of the Anhimidae, especially in combination with Anseranas, also undermined the support for this inference. Placement of Presbyornis as the sister group of the Anatidae casts doubt on the role suggested by Feduccia of ‘transitional shorebirds' in the origin of modern avian orders, and calls into question the concept of ‘fossil mosaics’. The phylogenetic hypothesis is used to reconstruct an evolutionary scenario for selected ecomorphological characters in the galliform-anseriform transition, to predict the most parsimonious states of these characters for Presbyornis, and to propose a phylogenetic classification of the higher-order taxa of waterfowl. This re-examination of Presbyornis also is used to exemplify the fundamental methodological shortcomings of the intuitive approach to the reconstruction of phylogenetic relationships.  相似文献   

17.
The archaeological excavation of the cave of the Gardon has brought to light a dilated and nearly continuous stratigraphy for the Neolithic era. The analysis of lithic industry has showed the existence of variations between those neolithic layers, which are independents of the technological processes of tools productions. Four criteria allow us to characterize the occupation’s type of each layer. Compared to the excavations data and to sedimentological analysis, these results allow us to display the evolution of the intensity of occupations of the cave throughout the whole Neolithic.  相似文献   

18.
The natural host range of entomopathogenic nematodes of the genera Steinernema and Heterorhabditis can be defined as the range of insects which indigenous nematode populations use for propagation. Information on the natural host range is rare. However, based on records of insects found to be naturally infected with nematodes, some conclusions regarding the natural host range of some Steinernema spp. and Heterorhabditis spp. are presented. Reports of indigenous nematode populations impacting on insect populations can be divided between relatively balanced, long-lasting nematode-host associations and unbalanced, short-lasting epizootics. Examples of the augmentation and inoculative introduction of nematodes in agriculture and forestry ecosystems are presented. Based on current knowledge, nematode reproduction strategies are discussed and indications of the risk involved in the release of non-indigenous nematodes are given.  相似文献   

19.
The reference ranges of the trace elements Al, As, Be, B, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, Li, Rb, Se, Sr, and Zn were determined by inductively coupled plasma-mass spectrometry (ICP-MS) in sera of a group of free-ranging plains viscachas of the pampa grasslands of Argentina. The values were compared with those of a small group of captive plains viscachas of the Zurich Zoo with diabetes and bilateral cataracts. In addition, a method for digestion of whole-blood samples is described for the trace element determination. Significant differences in the concentration of trace elements in the two groups of animals are discussed. No correlation was found between the levels of selenium and of other trace elements compared to the formation of cataracts.  相似文献   

20.
The field slug, Deroceras reticulatum (Muller), is probably the most damaging and widespread species of slug, causing severe economic losses in a broad range of crops in temperate zones throughout the world. Investigations into the role of predation in the population dynamics of this species required a biochemical system which was capable of identifying the remains of this slug in the crop contents of predators, and distinguishing them from those of other molluscs. A monoclonal antibody was developed (IgM isotype). This was capable of separating, in an enzyme-linked immunosorbent assay, D. reticulatum from the related D. caruanae (Pollonera) and all molluscs and other invertebrates tested, with the unexpected exceptions of New Zealand flatworms, Artioposthia triangulata (Deny) and the millipede Polymicrodon polydesmoides (Leach). Characterization of the antibody and assay demonstrated that the system could clearly detect as little as 11.6 ng of D. reticulatum protein in 200 mu l of buffer. Slug remains could be identified as such in the crops of the carabid predator Pterostichus melanarius Illiger for 38.1 h, while the antibody-antigen reaction declined to half of that measured immediately following consumption, after 12.9 h. A practical and highly sensitive system was therefore developed, using the first species-specific monoclonal antibody available for the investigation of predation on slugs.  相似文献   

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