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1.
Despite the traditional focus on metaphysical issues in discussions of natural kinds in biology, epistemological considerations are at least as important. By revisiting the debate as to whether taxa are kinds or individuals, I argue that both accounts are metaphysically compatible, but that one or the other approach can be pragmatically preferable depending on the epistemic context. Recent objections against construing species as homeostatic property cluster kinds are also addressed. The second part of the paper broadens the perspective by considering homologues as another example of natural kinds, comparing them with analogues as functionally defined kinds. Given that there are various types of natural kinds, I discuss the different theoretical purposes served by diverse kind concepts, suggesting that there is no clear-cut distinction between natural kinds and other kinds, such as functional kinds. Rather than attempting to offer a unique metaphysical account of 'natural' kind, a more fruitful approach consists in the epistemological study of how different natural kind concepts are employed in scientific reasoning.  相似文献   

2.
The three categories of the seafloor highs provided for in Article 76 of the 1982 United Nations Convention on the Law of the Sea should be interpreted from the legal perspective and in light of the principle of the natural prolongation. “Oceanic ridges of the deep ocean floor,” which are not part of the natural prolongation of the land territory of the coastal state, are the submarine features that have no geomorphological continuity with the landmass of the coastal state. “Submarine elevations,” which are not only part of the natural prolongation of the land territory of the coastal state but also the natural component of the continental margin, are those submarine features that have geomorphological as well as geological continuity with the landmass of the coastal state. “Submarine ridges,” which are part of the natural prolongation of the land territory of the coastal state but not the natural component of the continental margin, are those submarine features that have geomorphological continuity with the landmass of the coastal state. There are some clear trends as well as obvious variances in the practice of the Commission on the Limits of the Continental Shelf in this regard.  相似文献   

3.
多样化的棉田生态系统控害保益功能特征研究   总被引:12,自引:2,他引:12  
应用数量分析与能量测定相结合的方法 ,定量地分析和比较了华北棉区多样化的套间作棉田生态系统与单作棉田生态系统中主要害虫、天敌的种群动态及其天敌对害虫的控制作用 .结果表明 ,多样化的套间作系统中苗蚜与 2代棉铃虫发生轻 ,而伏蚜与 3代棉铃虫发生重 ;套间作系统有利于天敌群落能量的生产 ,尤其是利于捕食性蜘蛛类群的能量生产 ;从棉田生态系统棉株 害虫 天敌相互作用关系来看 ,尽管间套作系统内天敌群落生产力增加 ,保护益虫 (天敌 )作用好 ,同时也增加了害虫群落生产力 ,其控害功能较差 .  相似文献   

4.
Both natural and anthropogenic processes are responsible for excessive organic loading of submerged soils, with detrimental environmental consequences. The often insufficient natural attenuation can be enhanced by exploiting microbial manganese cycles. This review describes how an anoxic oxidation of organic matter with concomitant reduction of MnO 2 can link up with a reoxidation of the resulting, soluble Mn(II) in oxic layers. The potentially attainable oxidation rates through these natural cycles are of the same order as the organic carbon accumulation rates. The microbiology and physiology of the responsible organisms are discussed, as well as examples of naturally occurring manganese cycles and the possibility to engineer this natural phenomenon.  相似文献   

5.
苏珊  姚爱静  赵庆磊  田盈盈  周丁扬 《生态学报》2019,39(22):8319-8326
合理的资源保护分区有助于提高国家公园自然资源保护措施的区域针对性,增强保护效果。以北京长城国家公园体制试点区为例,从"生态本底"、"资源特征"以及"人类干扰"三方面选取要素指标,构建了国家公园自然资源保护分区指标体系。将林小班作为分区单元,根据园区的生态本底特征将其划分为7个自然资源保护区,并以此作为国家公园开展资源调查和管理工作的基本区划单位;根据各区域具体的资源问题和保护需求将国家公园进一步细分为17种自然资源保护区域,形成了包含两个层次的自然资源保护分区方案,并基于各个保护区的保护目标提出了相应的保护措施。该分区方案避免了国家公园现存的各类用地空间布局交叉或错位所导致的难以协调问题,有利于实现国家公园自然资源保护分区方案的落地和自然资源的有效保护。  相似文献   

6.
孙佳照  张淋  李子朝  邹运鼎  毕守东 《生态学报》2021,41(20):8297-8307
为了明确与假眼小绿叶蝉空间关系密切的天敌种类,为合理利用和保护天敌提供科学依据。运用地学统计学分析方法计算白毫早茶园、黄山大叶种茶园、农抗早茶园、平阳特早茶园和乌牛早茶园秋冬季假眼小绿叶蝉和其主要6种天敌地统计学半变异函数的变程。使用灰色系统分析方法对计算结果进行灰色关联度分析,并对分析结果进行标准化。以标准化后的密切指数大小评判天敌与假眼小绿叶蝉空间关系的密切程度。结果是:1)、黄山大叶种茶园和农抗早茶园与假眼小绿叶蝉空间关系密切的前3位天敌是粽管巢蛛、鳞纹肖蛸和斜纹猫蛛,但位次不同。2)、白毫早茶园前3位天敌是鳞纹肖蛸、斜纹猫蛛和锥腹肖蛸,前2种与黄山大叶种和农抗早茶园相同。3)、平阳特早茶园前3位天敌是鳞纹肖蛸、粽管巢蛛和草间小黑蛛,前2种与黄山大叶种和农抗早茶园相同。4)、乌牛早茶园前3位天敌是粽管巢蛛、草间小黑蛛和三突花蟹蛛,只有粽管巢蛛与黄山大叶种和农抗早茶园相同。根据5种茶园同种天敌密切指数之和以及同种天敌位次之和评判,与假眼小绿叶蝉空间关系密切的天敌均是鳞纹肖蛸、粽管巢蛛和斜纹猫蛛。天敌位次的变化主要是害虫和天敌数量之比的比值变化。害虫个体数与某种天敌个体数之比的比值越小,天敌与害虫的跟随关系则越密切。密切原因与食饵资源短缺有关。  相似文献   

7.
The data are provided on the efficacy of the use of the beta-adrenoblocker inderal and the natural antioxidant vitamin E as agents that prevent the immobilization stress-induced depression of the activity of natural killers. The problems of the prevention of the action of excess catecholamines and activation of lipid peroxidation as pathogenetic component in the development of stressor depression of the activity of natural killers are discussed.  相似文献   

8.
We present examples of large‐scale farmer‐managed natural regeneration of woody species in Africa to create new agroforestry systems. We also analyze two cases in Ethiopia of large‐scale natural regeneration. The available evidence shows that the average costs per hectare of promoting on‐farm natural regeneration are low as soon as farmers are familiar with this practice and begin to spontaneously adopt it. Based on these cases, current ambitious forest restoration targets can be achieved, but this goal requires a shift from tree planting to assisted natural regeneration. We propose a scaling‐up strategy for natural regeneration based on experience gained mainly in the West African Sahel.  相似文献   

9.
Tropical plantations are rapidly expanding as a source of industrial wood. In Indonesia, such large-scale industrial plantations are generally made of large mono-specific blocks interspersed with natural forest remnants. The extent and biodiversity value of these remnants vary as laws and regulations on their design and management are either unclear, without solid scientific basis or left to the interpretation of private companies responsible for the plantations. Our study area comprises of three Acacia mangium plantations, which have on average 18% of their total area set aside from production and conserved as natural forests. These remnant natural forests may, if appropriately designed and managed, be used to mitigate the negative impact of plantations on biodiversity by providing some degree of connectivity with and between remaining natural forest patches (such as the Tesso Nilo conservation area). We sampled natural vegetation in one and primate diversity in all three plantation sector and examined patterns of primate species richness and abundance with relation to spatial arrangement and dimensions of conservation area, which has been set aside from plantation production. We demonstrate unambiguously the critical importance of a well-connected network of natural forest corridors in the plantation landscape to maintain primates and discuss the potential biodiversity value of natural forest remnants in broad-scale industrial landscapes.  相似文献   

10.
Natural product substances have historically served as the most significant source of new leads for pharmaceutical development. However, with the advent of robotics, bioinformatics, high throughput screening (HTS), molecular biology-biotechnology, combinatorial chemistry, in silico (molecular modeling) and other methodologies, the pharmaceutical industry has largely moved away from plant derived natural products as a source for leads and prospective drug candidates. Can, or will, natural products ever recapture the preeminent position they once held as a foundation for drug discovery and development? The challenges associated with development of natural products as pharmaceuticals are illustrated by the Taxol® story. Several misconceptions, which constrain utilization of plant natural products, for discovery and development of pharmaceuticals, are addressed to return natural products to the forefront.  相似文献   

11.
Natural products are valuable resources that provide a variety of bioactive compounds and natural pharmacophores in modern drug discovery. Discovery of biologically active natural products and unraveling their target proteins to understand their mode of action have always been critical hurdles for their development into clinical drugs. For effective discovery and development of bioactive natural products into novel therapeutic drugs, comprehensive screening and identification of target proteins are indispensable. In this review, a systematic approach to understanding the mode of action of natural products isolated using phenotypic screening involving chemical proteomics-based target identification is introduced. This review highlights three natural products recently discovered via phenotypic screening, namely glucopiericidin A, ecumicin, and terpestacin, as representative case studies to revisit the pivotal role of natural products as powerful tools in discovering the novel functions and druggability of targets in biological systems and pathological diseases of interest.  相似文献   

12.
天然水凝胶是指原材料来自于天然生物材料的水凝胶。由于这种天然的聚合物含有构成生物体的天然成分,与天然组织具有生物学和化学相似性,而受到特别关注。天然水凝胶由于其与细胞外基质高度的相似性被认为是骨组织工程中优良的仿生基质材料。而针对天然水凝胶机械性能差、成骨诱导性能弱等缺陷,通常需要对天然水凝胶进行改性、引入其他材料或生物活性因子,以此来获得更适用于骨组织工程支架材料。对近年来基于天然水凝胶的生物材料在骨组织工程的应用,与其不同的应用形式(可注射水凝胶、多孔水凝胶支架、3D生物打印水凝胶支架等)进行了概述,以期对这类基于天然水凝胶的生物材料在未来骨组织工程中的应用提供参考。  相似文献   

13.
长江经济带自然保护地边界重叠关系及整合对策分析   总被引:2,自引:0,他引:2  
靳川平  刘晓曼  王雪峰  孙阳阳  付卓  王超  候静 《生态学报》2020,40(20):7323-7334
我国自然保护地类型多样,级别成体系,但由于我国自然保护地一直存在多头管理、权限不清等原因,导致边界混乱、重叠严重。对我国自然保护地空间分布和重叠情况进行梳理是构建以国家公园为主体的自然保护地体系的重要基础,能为我国新型自然保护地的科学选址和优化整合提供有效依据。长江经济带作为我国生态、生活、生产均十分重要的区域,其生态保护具有重要的屏障作用。收集了长江经济带11省份建设开展较成熟的6类自然保护地矢量边界2383个,通过构建重叠关系模型,深入分析了不同类型自然保护地间的边界重叠关系,并针对重叠情况提出系统化对策,结果表明:(1)保护地之间具有重叠关系的数量达1296个,占已获取保护地边界总数的54.4%;重叠部分面积达29728.4 km2,占已获取自然保护地总面积的11.4%;总体呈现为西部重叠面积大、数量多,中部重叠数量多,东部重叠面积小的特点。(2)从重叠区域看,有一次重叠区域的保护地有1138组,有两次重叠区域的有249组,有三次重叠区域的有17组,无四次及以上重叠区域。(3)从重叠关系看,与其他5个及以上保护地有重叠的保护地有56个。(4)通过对重叠区域和关系的分析与政策研究,提出针对不同重叠特性的整合对策,包括勘界调整、合并和类型整合等,并将重叠热点区域提取,以期为自然保护地整合和国家公园建设提供数据支撑,为当前中国自然保护地体系改革的紧迫需求提供参考。  相似文献   

14.
在害虫测报和防治工作中,经常要考虑天敌与害虫数量的比例问题,以决定是否需对害虫进行防治或决定相应的防治措施。如果采取防治措施过早,不能充分发挥天敌的自然控制作用,则会浪费人力物力;如采用化防还会加  相似文献   

15.
Are natural microcosms useful model systems for ecology?   总被引:2,自引:0,他引:2  
Several recent, high-impact ecological studies feature natural microcosms as tools for testing effects of fragmentation, metacommunity theory or links between biodiversity and ecosystem processes. These studies combine the microcosm advantages of small size, short generation times, contained structure and hierarchical spatial arrangement with advantages of field studies: natural environmental variance, 'openness' and realistic species combinations with shared evolutionary histories. This enables tests of theory pertaining to spatial and temporal dynamics, for example, the effects of neighboring communities on local diversity, or the effects of biodiversity on ecosystem function. Using examples, we comment on the position of natural microcosms in the roster of ecological research strategies and tools. We conclude that natural microcosms are as versatile as artificial microcosms, but as complex and biologically realistic as other natural systems. Research to date combined with inherent attributes of natural microcosms make them strong candidate model systems for ecology.  相似文献   

16.
Pathogens and arthropod natural enemies may contribute to the suppression of insect pest populations either as individual species or as species complexes. However, because natural enemies of insects have evolved and function in a multitrophic context it is important to assess interactions within complexes of natural enemies if they are to be exploited effectively in pest management. Natural enemies can interact either synergistically/additively (e.g. enhanced transmission and dispersal of insect pathogens) or antagonistically (e.g. parasitism/infection, predation and competition). In this paper, studies assessing the potential interactions between insect and fungal natural enemies are reviewed. In general, these studies indicate the positive nature of the interactions between arthropod natural enemies and fungal pathogens with respect to the control of insect populations. More work is required to investigate further the many ways in which the natural enemy community interacts in the agroecosystem  相似文献   

17.
In this paper, the ecological integrity hierarchy framework (EIHF) and the natural capital index framework (NCI) are integrated as decision-making tools for evaluating the natural capital of Mexico. Two hierarchy-levels of ecological integrity indicators are used to estimate the quality and quantity of the natural capital, the amount of ecological degradation and ecological sustainability. After human transformation, the extent still considered as “natural” in the country is ∼67%; while the amount of human transformed areas is ∼33%, which gives a total estimate of NCI = 0.334; i.e., only ∼33.4% of the national capital remains available, while ∼33% is ecologically degraded. Furthermore, the critical natural capital; i.e., the legacy for future generations that remains in the country is only ∼12%. The total estimated value of the current natural capital in Mexico is ∼$457.1 billion/yr, which is ∼435 times greater than the national GDP ($1.051 billion in 2010). The cost of maintaining the degradation of the natural capital is ∼$144.6 billion/yr (∼138 times greater than national GDP in 2010). The potential value of the natural capital after restoration would be ∼$602 billion/yr. Valuing the natural capital can be helpful for strategic environmental evaluations and useful for spatial decision support systems that evaluate natural capital as a decision-making tool.  相似文献   

18.
Plants used as natural dye sources in Turkey   总被引:1,自引:0,他引:1  
This study was carried out in the regions where handcrafts such as carpet and rug weaving are common in Turkey. In the regions where natural dyes are used, 123 plant species belonging to 50 families were identified as sources of natural dyes. In natural dye production, different parts of the plant or the whole aboveground plant is used. Ten different colors are gained from the plants. Sometimes the same color can be obtained from different plants. By mixing different plants, it is possible to produce various colors. We also identified more than 12 natural and more than eight chemical assistant substances (mordant) that are used in the regions to bind dye to fibers, to maintain the strongness and brightness of the colors, and to obtain various colors  相似文献   

19.
徐飞  邓子新  林双君 《微生物学通报》2013,40(10):1796-1809
氨基酸作为生物体内组成生命物质的小分子化合物, 在天然产物生物合成中扮演了非常重要的作用。色氨酸含有一个独特的吲哚环, 相对复杂的吲哚环平面结构使得色氨酸相比其他氨基酸具有更多的修饰空间。在微生物天然产物生物合成研究中, 色氨酸及其衍生物经常作为组成模块参与到天然产物的生物合成中, 本文概述了色氨酸几种不同的生物修饰方式, 包括烷基化修饰、卤化修饰、羟基化修饰、以及吲哚环的开环重排反应等。分析并总结色氨酸在天然产物生物合成中的作用可以增加我们对天然产物结构多样性的认识和推动天然产物生物合成机制的研究。  相似文献   

20.
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