查询词典 niche

1Niche construction can lead to stable coexistence of diverse genotypes in spatially structured population, which supports a stable polymorphism even without heterozygote superiority.(2)With habitat deterioration, niche construction accelerates the formation of steady polymorphism and hence impedes the harmful influences of environment on the population, which might embody a life-history strategy of organism under the unfavorable environment.(3)Niche construction results in the coexistence with alternative polymorphism through genotype-environment feedback and limited gene flow.(4)The niche-constructing organism is an active force to alter its environment and hence the direction of natural selection in order to better survival.(5)Spatial dynamics and distribution pattern of metapopulation are profoundly influenced by time-lagged niche construction.(6)Metapopulation size can reach a fixed level in the recency effect and equal weighting of time lag but is statistical stability in primacy effect, which implies the primacy effect is most remarkable.(7)The increment in the relative weightingof each generation\' niche construction and the length of time lag are significant factors for system destabilization.(8)Moderate capacity of positive niche construction benefits the metapopulation persistence.(9)The narrowing of niche breadth can decrease the metapopulation size and thereby increase the extinction risk.(10)The coupled function of time lag and niche construction make the system oscillation and generate the spiral wave, spiral-broken and circular wave in heterogeneous habitat.The spatial distributions of metapopulation and resource content are complementary due to a phase lag of their both frequencies.(12)Metapopulation persistence with niche construction depends not only on the balance between colonization and extinction, but also on the balance between the ability of niche construction and natural dissipation of habitat.(13)Metapopula-tion can survive under certain condition when the percent of suitable patches in habitat is lower than the ration of extinction to colonization.(14)Two thresholds exist in the process of transition of habitat quality dynamics from unsuitable to suitable, which include the intensity of niche construction and the initial condition of system.(15)Metapopulation size is positive correlated with the ability of positive niche construction, which means that organism or population who has strongly positive influences on their environment plays an important role to maintain the available habitat.

通过上述几个方面的研究，主要得出以下15条结论：(1)生态位构建可使空间结构种群，甚至是在没有杂合子优势的条件下，形成多种可能的稳定基因型分布模式；(2)随着环境的破坏与恶化，种群的生态位构建作用加速其较早形成稳定多态以阻碍环境对种群的不利影响，解释了有机体在不利环境下的一种生活史对策；(3)生态位构建作用通过基因型—环境反馈机制及有限的基因交流导致基因型多态的稳定共存；(4)有机体的生态位构建作用是一种积极的动力改变环境进而改变其自然选择的方向；(5)生态位构建的时滞作用对集合种群动态和空间分布产生深刻影响；(6)集合种群大小在时滞的崭新效应和等权重效应下达到一固定值，而在首位效应下达到统计稳定，表明首位效应的影响最显著；(7)首位效应下生态位构建相对权重的增量和时滞的长度是影响系统不稳定性动态的关键因素；(8)适中的生态位构建强度有利于集合种群的续存；(9)生态位宽度变窄会减少集合种群的数量从而增加其灭绝风险；(10)时滞和生态位构建的双重作用使系统产生周期振荡，并在异质性环境中产生稳定的螺旋波，破碎的螺旋波和环形波三种分布模式；(11)集合种群与资源含量的空间分布因为相滞而互补；(12)具有生态位构建的集合种群续存不仅取决于侵占率与灭绝率之间的平衡，而且依赖于生态位构建能力同其生境的自然消耗速率之间的妥协；(13)当生境中适合侵占的斑块比例小于其侵占率与灭绝率之比时，生态位构建作用促使集合种群在一定条件下续存：(14)生境斑块的状态从不适合到适合转变过程中存在生态位构建强度和系统初始条件这两个阈值；(15)集合种群的大小同正生态位构建能力正相关，意味着对环境具有较强正作用的有机体对维持有效生境起积极作用。

Although many scholars had attempted to define it, the typical definitions of niche are Grinnell's space niche, Elton's functional niche and Hutchinson's hypervolume niche; Niche metrics include niche breadth, niche overlapping, niche volume and niche dimension, among which niche breadth and niche overlapping are two important indexes that can be used to characterize a species niche and the relationships between species niches.

许多学者都试图给生态位下定义，但最具代表性的当推Grinnell、Elton和Hutchinson分别给出的&空间生态位&、&功能生态位&和&多维超体积生态位&定义；生态位测度包括生态位宽度、生态位重叠、生态位体积及生态位维数等，其中生态位宽度和生态位重叠是描述一个物种的生态位以及物种生态位间关系的重要指标。

It showed that the niche breadth and niche overlapping indexes of the enclosed grassland in 2007 are much lower than in 2006 as a whole; The niche breadth of Artemisia ordosica is bigger than other species in the region in 2002. In 2003, the dominant species were Artemisia ordosica and Salsola ruthenica. Their niche breadth indexes were 0.544 and 0.460 respectively. The results of niche overlapping in 2006 and 2007 also showed that the species with big niche breadth didn't always have big niche overlapping, and the niche breadth and niche overlapping did not have a positive direct linear relation.

结果表明：2007年封育区植物种的生态位宽度及种间的生态位重叠指数总体上较2006年有所降低；2006年黑沙蒿生态位宽度最大，达0.768，是06年封育区的优势种；2007年封育区的优势种为刺沙蓬和黑沙蒿，其生态位宽度值分别为0.544、0.460；2006年和2007的生态位重叠结果均表明，生态位宽度大的物种不一定和其他物种有大的重叠指数，较高的生态位宽度和较高的生态位重叠之间并不存在直接的线性关系；2006年、2007年较高的Pianka生态位重叠指数都出现在生态位宽度较小的物种之间。

By taking cotton fiber in high yield cotton field of north Xinjiang as the object, the niche-fitness theory were introduced, through analysis the niche-fitness of cotton fiber in three mono-topping and multi-topping intercrop system treatment, the result showed, it is acceptable that evaluate cotton fiber quality by niche-fitness, the niche-fitness value of cotton fiber at the middle part of the cotton plant is the biggest that topping inJul.10th and Jul.25th in this three treatment, moreover, with the increase of topping times, compare with it's top part of cotton plant, the niche-fitness of cotton fiber at the low part of cotton plant have a raise tendency, the niche-fitness value of top and low part of cotton plant in multi-topping treatment is bigger than what of mono-topping.

以北疆高产棉田棉纤维作为研究对象，引入生态位适宜度理论，对三个打顶次数不同的处理的棉花群体棉纤维生态位适宜度进行分析研究，结果表明：用生态位适宜度来评价棉纤维品质是切实可行的，三个打顶处理中7月10日和7月25日打顶棉株棉纤维生态位适宜度均为中部最高，并且随着棉花群体打顶次数的增加，其下部棉纤维生态位适宜度较上部有逐渐增高的趋势，与一次打顶相比较，其二、三次打顶棉株上、下部棉纤维生态位适宜度均升高。

Niche which many ecologists have become interested in is an important concept in ecology. The main definitions of niche are the habitat niche of Grinnell (1917), the functional niche of Elton (1933) and the hypervolume niche of Hutchinson (1957) whose concept has by far the largest influence on niche.

生态位是生态学的一个重要概念，许多生态学家都对生态位下了定义，主要有Grinnell(1917)的生境生态位，Elton(1933)的功能生态位，Hutchinson(1957)的超体积生态位，尤以Hutchinson的&超体积生态位&影响为大。

Based on Hutchinson niche and Guangxia Cao\'s definition, Fuzzy hypervolume niche evolves the theory of fuzzy niche: the niche is a fuzzy hypervolume; the niche of the species is a hypervolume with fuzzy boundary which is formed by the n-dimensional resources (time, space, temperature, humid, trophic,...) necessary for the species\' continuous existing and multiplying; membership of a point in the niche is equivalent to the adaptive degree of the species to the point of the environmental resources.

在Hutchinson生态位和Guangxia Cao的定义的基础上，模糊超体积生态位发展了模糊生态位理论：物种的生态位是可以使物种生存和不断繁殖的n维环境变量(时间、空间、温度、湿度、营养……)所形成的边界模糊的一个n维超体积；隶属函数表明n维资源空间的一个点x属于生态位的程度，也表明物种对环境资源的适应程度。

The main definitions of niche are the habitat niche of Grinnell (1917), the functional niche of Elton (1933) and the hypervolume niche of Hutchinson (1957) whose concept has by far the largest influence on niche.

生态位是生态学的一个重要概念，许多生态学家都对生态位下了定义，主要有Grinnell(1917)的生境生态位，Elton(1933)的功能生态位，Hutchinson(1957)的超体积生态位，尤以Hutchinson的&超体积生态位&影响为大。

In order to find the vegetable niche pattern in arid and semi-arid grassland region, the niche breadth and niche overlapping in Yanchi county of Ningxia in 2006 and 2007 are measured by means of Levins niche breadth and Pianka niche overlapping indexes in the enclosed grassland.

运用Levins生态宽度指数及Pianka生态位重叠指数，对宁夏盐池人工封育草原2006年和2007年植物生态位宽度及生态位重叠进行计量，以了解干旱半干旱区草原植物生态位格局。

Using the Shannon-Wiener's niche breadth index and the Pianka's niche overlaps index, we found that the Nereis japonica, nemerteans and eelworms had broad niche breadths (above 2.80); the niche overlaps among them was high (above 0.90) in the quantitative analysis on the 21 species present in the quantitative sample analysis.

对定量取样中获得的21个物种以Shannon-Wiener指数为基础进行了生态位宽度测定，以Pianka重叠指数为基础进行了生态位重叠值分析，结果表明日本沙蚕、纽虫和线虫的生态位较宽，均为2.80以上，它们之间的生态重叠值也较高，均为0.90以上。

Fuzzy hypervolume niche was proposed to overcome the limitation of Hutchinson\'s niche concept and the formulas to measure two important indexes—niche width and niche overlap which can be easily applied in practice.

为克服Hutchinson的生态位定义的局限提出了模糊超体积生态位，以及度量生态位的两个重要指标——生态位宽度和生态位重叠，新公式便于应用。

More direct, directer ; most direct, directest

径直的，笔直的

Do you know how to use a chain saw?

你知道如何使用链锯吗？