普通生态学课件：普通生态学课件

一、WHAT IS ECOLOGY?
A definition of ecology
Ecology is the study of the interactions between organisms and their environment,The ‘environment’ is a combination of the physical environment (temperature,water availability,etc.) and any influences on an organism exerted by other organisms-the biotic environment.
生态学的定义生态学是研究有机体与其环境相互作用的科学。“环境”是物理环境（温度、可利用水等）和生物环境（对有机体的、来自其他有机体的任何影响）的结合体。
生态学的定义,研究生物与其环境相互关系的科学
内涵：1）环境对生物的决定和塑造作用
2）生物对环境的适应
3）适应环境的生物对环境的改善作用为什么要开展生态学研究
人类面监的四大危机：
（1）环境危机
（2）人口危机
（3）资源危机
（4）能源危机
Individuals,populations,communities and ecosystems
There are four identifiable subdivisions of scale which ecologists investigate;
(i) considering the response of individuals to their environments;
(ii) Examining the response of populations of a single species to the environment,and considering processes such as abundance and fluctuations;
(iii) The composition and structure of communities (the populations occurring in a defined area);
(iv)the processes occurring within ecosystems (the combination of a community and the abiotic components of the environment),such as energy flow,food webs and the cycling of nutrients.
个休、种群、群落和生态系统生态学所研究的有4个可辨别尺度的亚部分：
(i)探讨个体对其环境的反应；
(ii)研究单个物种的种群对于环境的反应，和探讨诸如多度(abundance)及其波动等的过程（iii）群落（出现在确定面积中的种群集合）的组成和结构；(iv)生态系统（群落与环境的非生物成分的结合）内的各种过程，例如能流、食物网和营养物的循环等。
生态学的交叉学科
在生物学内的交叉：生理生态学，生态遗传学，行为生态学，…
与自然科学的交叉：数学生态学，化学生态学，… …
与人文、经济和社会科学的交叉：经济生态学，社会生态学，政治生态学，人类生态学，民族生态学，哲学生态学，… …
生态学的研究方法
1.4.3 生态学研究问题的步骤
TEN RULES IN ECOLOGY?
What are these rules?
The authors’ experience of teaching ecology has given them experience of some common pitfalls which ecology students often make,This list,designed to counter these pitfalls,is neither comprehensive nor mutually exclusive,but we hope will nevertheless serve as a useful guide to protocol,
这些规律是什么？
生态学的授课实践使得本书作者能够觉察到大学生学习生态学时常常陷入的某些一般性错误。本目录是为克服这些错误而设计的，既不全面，也不互相排斥，但是我们希望它将作为有用的指南。
Rule 1 Ecology is a science.
Ecology is a purely scientific discipline which aims to understand the relationships between organisms and their wider environment,It is important to segregate political and social impacts of ecological understanding from the scientific viewpoint.
规律1：生态学是科学生态学是一门纯科学学科，目标是了解有机体与其广阔环境的相互关系。分清楚科学观点与生态学知识的政治和社会影响这一件事是十分重要的。
Rule 2 Ecology is only understandable in the light of evolution.
The huge diversity of organisms,and the wealth of variety in their morphologies,physiologies and behavior are all the result of many millions of years of evolution,Those evolutionary history has left an indelible impression on each and every individual,It is only possible to make sense of the patterns we find today in the light of this evolutionary legacy.
规律2：生态学只有按照进化论才可理解有机体巨大的多样性，以及其形态学、生理学和行为的变异的丰富性，全都是亿万年进化的结果。这个进化历史对于每一个个体都留下了不能去除的影响。我们今天发现的种种模式，只有按照进化论的观点才可能有意义。
Rule 3 Nothing happens’ for the good of the species’.
A very common misconception is the idea that patterns of behavior in organisms which appear to be costly to an individual occur’ for the good of the species’,This is absolutely and completely wrong,Natural selection will favor those genes which are passed on to the most offspring,even if these genes may cause a reduction in the species’population size.
规律3：“对动物种有利”现象并不存在对于那些看起来对个体是花费的有机体行为模式，认为其出现是由于“对物种有利”的这种想法是一个非常普遍的误解。这是绝对和完全错误的。自然选择将会有利于那些传给大多数后裔的基因，即使这些基因有可能导致物种种群大小的下降。
Rule 4 Genes and environment are both important,
The environment an organism finds itself in plays an important role in determining the options open to that individual,The genes which define an organism’s makeup are also of fundamental importance,To understand ecology it is important to appreciate the fundamental nature of both of these factors and the fact that they interact.
规律4：基因和环境都很重要有机体自己所处的环境，对于它在开放的各种选择中决定取舍上，具有重要的作用。决定有权体构造的基因，同样具有根本的重要性。这两方面因素的基本性质及其相互作用，对于理解生态学都是很重要的。
Rule 5 Understanding complexity requires models.
Ecology is a complex subject,with huge variation at almost every scale-millions of species,each with considerable genetic variation,varying numbers and ever-changing behaviors in a complex and dynamic environment,To understand it,it is necessary to clearly identify specific questions and then formulate hypotheses which can be tested,It is often very useful to frame the hypothesis in mathematical terms to avoid ambiguity and confusion which are often inevitable in a verbal model,Mathematical models are widely used in ecology.
规律5：理解复杂性要求模型生态学是一复杂的对象，几乎每一个尺度都有大量变异——亿万个种，每种有大量基因变异，在复杂和动态的环境中有变化着的数量和随时间而改变的行为。为了理解它，必需清楚的认明特异问题，然后形成可以检验的假设。以数学的思想方法构造假说常常是很有用的，可以躲开在语言模型中不能避免的含糊不清和混淆。数学模型在生态学里被广泛的应用。
Rule 6 ‘Story-telling’ is dangerous.
In attempting to explain ecological patterns or relationships,it is easy to slip into a make-believe world where every observation is readily explained by some ad hoc assertion – ‘story-telling’,The temptation to advance hypotheses as facts should be avoided at all costs.
规律6：“讲故事”是危险的在打算解释生态学种种模式或相互关系的时候，人们很容易滑到虚假世界之中，每一个观察都很容易的被某特设的断言（所谓的“讲故事”）所解释了。无论如何，总想去推进假设实际上是应该避免的。
Rule 7 There are hierarchies of explanations.
For any observation there is often an immediate cause that can be diagnosed,Often this causal explanation is insufficiently informative and we need to probe deeper to reach a fuller grasp of the situation,Even if a phenomenon is ‘explained’ there may well be further and deeper explanations which allow us to see the fuller picture.
规律7：要有分层次的解释对于任何观察，常常可以识别出一个直接的原因，但这种因果解释往往是资料不足的，我们需要进一步探索，以达到更完全的抓住情况。即使是现象已经被“解释”了，更进一步和更深入的解释也是很好的，它允许我们看见更完全的情景。
Rule 8 There are multiple constraints on organisms.
Whilst the total diversity of form,function and environmental resilience exhibited by organisms is awe-inspiring,each individual (and,to a slightly lesser extent,each species) operates within a relatively narrow range of constraints,Constraints fundamentally take two forms,(i) physical and (ii) evolutionary,Evolution cab never reach ‘perfection’ because of these constraints and organisms are essentially hotchpotches of numerous compromises,
规律8：有机体具有很多限制有机体表现出来的形态、功能和环境适应力的总多样性是令人惊叹的，每个个体（和每一个种，但较少程度）则在相对较小的约束范围中运转。约束基本上有两类：（i）物理的，（ii）进化的。由于这些约束，进化从来就没有达到“完善”过，有机体基本上是许多妥协的杂烩。
Rule 9 Chance is important.
Chance events play a critical role in ecology,The opening of a gap in a forest canopy or the breaching of a sand dunce after a storm will have a major impact on the ecology of the local fauna and flora,but both are unpredictable in either time or location,The importance of chance events in ecology does not mean ecological patterns are wholly unpredictable,but it necessarily places boundaries on the potential level of predictive detail.
规律9：机会是重要的随机事件在生态学中起关键性的作用。林冠中出现林窗或沙丘在风暴后裂口，对于当地动植物区系将有重要的影响，但是，林窗和裂口出现的时间和地点都是不可预测的。机会的作用也与有机体过去进化综合在一起。生态学中机会事件的重要性并不意味着生态学中的模式是完全不可预测的，但是它必然是位于预言细节的潜在水平之边缘。
Rule 10 There boundaries of ecology are in the mind of the ecologist.
Ecology is a broad science,covering both organisms and physical environments and hence excludes little as potentially relevant,Mathematics,chemistry and physics are tools essential to the understanding of ecology.
规律10：在生态学家心目中的生态学边界生态学是一门广泛的科学，覆盖着生物和物理环境，从而作为潜在相关的，很少有被排除在外的了。数学、化学和物理学都是理解生态学的基本工具。
二、ADAPTATION
Fitness
Fitness is measure of the ability of an individual to produce viable offspring and contribute to future generations,Individuals vary in their relative fitness,and this variation is due partly to genetic differences among individuals and partly to environmental influences.
适合度适合度是个体生产能存活后代、并能对未来世代有贡献的能力的指标。个体的相对适合度是有变化的，这种变化部分决定于个体的遗传区别，部分决定于环境的影响。
Adaptation
Any heritable trait possessed by an organism which aids survival or reproduction is an adaptation,Such traits may be physiological,morphological or behavioral,Adaptation is the result of natural selection.
适应有机体所具有的有助于生存和生殖的任何可遗传特征都是适应。适应性特征可以是生理的、形态的或行为的。适应是自然选择的结果。
Natural selection
The individuals in a species which have the highest fitness will contribute disproportionately to the subsequent generations,If fitness differences have a genetic component,then the genetic make-up of the subsequent generations will be altered,This process is known as natural selection or ‘survival of the fittest’.
自然选择种中具有最高适合度的个体将会对未来世代作出特别高的贡献。如果适合度的差别含有遗传的成分，则后代的遗传组成会有改变。这个过程称为自然选择或“最适者生存”。
Genotype and phenotype
The genotype is the genetic composition of an individual,The phenotype is the individual organism,a product of the interaction between its genotype environmental influences on its genotype is known as phenotypic plasticity (e.g,human suntan,wind-shaped plants locust morph (solitary or migratory)).
基因型和表型基因型是个体的遗传组成。表型是各个有机体，它是基因型与环境的相互作用的产物。由于环境对基因型的影响，表型发生变化的能力叫做表型可塑性（如人的晒黑、风造形的植物、蝗虫的单生或群居型）。
三、COPING WITH ENVIRONMENTAL VARIATION
Conditions
Variable environmental factors which organisms respond to are conditions,Examples include temperature,acidity and salinity,Conditions are not depletable – they are not used up or consumed by an organism.
条件引起有机体对其反应的,可变的环境因子是条件(conditions)，例如温度、酸度和盐度。条件是不可能被减少的——它不能被有机体用掉或消耗掉。
Resources
Anything which the organism uses up or depletes is a resource for that organism,Thus,nectar is a resource for honey bees,and light is a resource for all green plants.
资源有机体消耗的任何东西，对该有机体而言，就是资源。例如，蜜是蜜蜂的资源，光是一切绿色植物的资源。
生态因子的相关概念生态因子：环境要素中对生物起作用的因子。
生存条件：生态因子中生物生存不能缺少的生态因子的总称。
生态环境：一定区域所有生态因子的总和。
生境（habitat）：特定生物个体或群体的栖息地的生态环境。
生态因子的分类
根据性质划分为,
气候因子：如温度、水分、光照、风、气压和雷电等
土壤因子：如土壤结构、土壤成分的理化性质及土壤生物等
地形因子：如陆地、海洋、海拔高度、山脉的走向与坡度等
生物因子：包括动物、植物和微生物之间的各种相互作用
人为因子：人类活动对自然的破坏及对环境的污染生态因子的分类有无生命特征：生物因子和非生物因子
对生物种群数量变动的作用密度制约因子：食物、天敌等生物因子
非密度制约因子：温度、降水等气候因子
稳定性及其作用特点
稳定因子：终年恒定的因子，决定生物的分布，如地心引力、地磁等
变动因子,
周期性变动因子：一年四季变化和潮汐涨落
非周期性变动因子：如风、降雨、捕食等生态因子的作用特征综合作用,生态因子间相互联系、相互影响、相互制约
主导因子作用：生态因子的非等价
作用的阶段性,生物发育的不同阶段，需要不同
不可替代性和补偿性：生态因子间不可替代，但在一定程度上可以补偿
直接作用和间接作用,
直接因子：直接对生物发生影响的生态因子
间接因子：通过影响直接因子而对生物发生影响生态因子限制因子和限制因子定律限制因子 (limiting factor)
-限制因子是对生物的生存、生长、繁殖或扩散等起限制作用的因子
-当生态因子接近或超过生物的耐受性极限而影响其生存、生长、繁殖或扩散时，这个因子成为该生物限制因子限制因子定律 (Law of limiting factor)
-生态因子处于低于生物正常生长所需的最小量和高于生物正常生长所需的最大量时，都对生物具有限制性影响 (Blackman，1905)
该定律的应用价值---掌握研究生物与环境复杂关系的钥匙
Environmental variation
Most organisms have to cope with a continually changing external environment over a range of timescales,Some environmental factors may change over seconds or minutes (e.g,sunlight intensity when,there is patchy cloud) whilst others may change daily or seasonally or over a much change daily or seasonally or over a much longer period (e.g,glaciation cycles).
环境变异大多数有机体都必须应付在一定时间尺度范围内不断变化着的外界环境。某些环境因子的变化以秒或分计（如当有云块时的阳光强度），另一些因子的变化以日或季计，甚至更长更长的时期（如冰河周期）。
tolerance
Organisms can cope with variation in their external environment (though different species may differ markedly),The upper and lower extremes of species limits of tolerance,Usually,growth will not occur at these extremes but in a narrower range of conditions,and fitness will be greatest only for a yet narrower optimal range.
耐受性有机体能够应付其外部环境的变化（虽然不同物质表现很不相同）。种的成员能够生存的环境条件上限和下限是种的耐受限度。在此极端条件下通常不出现生长，但在条件更狭窄的范围内能生长，而适合度最大只能出现在更窄的最适范围内。
生物对不同生态因子的耐受范围不同，不同年龄、季节、栖息地等同种生物对生态因子的耐受性不同
-对很多生态因子耐受范围都很宽的生物，其分布区一般很广
-个体发育的不同阶段，对生态因子的耐受限度不同
-不同的生物种，对同一生态因子的耐受性不同
-某一生态因子处于非最适状态下时，生物对其他生态因子的耐受限度也下降
Homeostasis
The maintenance of a relatively constant internal environment by an organism in a variable external environment is called homeostasis,All organisms adopt a degree of homeostatic control,but,as true,large organisms are more decoupled from their external environment than small ones.
稳态有机体在可变动的外部环境中维持一个相对恒定的内部环境，称为稳态（homeostasis）。一切有机体都采取一定程度的稳态控制，但是一般地说，大型有机体比小型的更易从其外部环境中退耦（decouple）。
Negative feedback
Most biological homeostatic mechanisms act in a broadly similar way,if the current internal level of a factor(e.g.temperature or osmolarity) is too high,the mechanism will reduce it; if the level is too low the mechanism will increase it,This process,by which the response is opposite to the signal,is known as negative feedback.
负反馈大多数生物的稳态机制以大致一样的方式起作用：如果一个因子的内部水平（如温度或渗透性）太高，该机制将减少它；如果水平太低，就提高它。这个过程叫做负反馈。负反馈反应的方向与信号的相反。
B3 THE NICHE
Niche
The ecological niche of an organism is the position it fills in its environment,comprising the conditions under which it is found,the resources it utilizes and the time it occurs there.
生态位有机体的生态位（niche）是它在它的环境中所处的位置，包括它发现的各种条件、所利用的资源和在那里的时间。
Multidimensional niche space
Each condition or resource which defines the niche of an organism contributes one dimension to the space in which the organism’s niche,and is the multidimensional niche space,or’n-dimensional hypervolume’.
多维生态位空间定义有机体生态位的每一个条件和资源，对于有机体能出现的空间提供一个维度。一起考虑所有维度，全面确定的有机体的生态位，是多维生态位空间，或“n-维超体积”。
Fundamental niche
The niche space an organism can fill in the absence of competition or predation is known as the fundamental niche.
基础生态位在没竞争和捕食条件下，有机体的生态位空间叫做基础生态位（fundamental niche）。
Realized niche
The niche space occupied by an organism when competition and predation occur is the realized niche,which is always a subset of the fundamental niche.
实际生态位当有竞争和捕食出现时，有机体所占有的生态位空间是实际生态位（realized niche），实际生态位始终是基础生态位的一个子集。
四、SOLAR RADIATION
Radiant energy and photosynthesis
Radiant energy is the sole energy source that can be used by green plants,When a leaf intercepts radiant energy it may be absorbed,reflected or transmitted,Part of the fraction absorbed reaches the chloroplast,fuelling photosynthesis,the process where radiant energy is used to convert water and CO2 into sugars,
Solar radiation contains a spectrum of different wavelengths,However,only a restricted band of this spectrum is effective for photosynthesis,This is the band of photosynthetically active radiation (PAR) and for green plants lies between 380 and 710 nm.
辐射能和光合作用绿色植物能够利用的惟一能源是辐射能。当叶子截获辐射能时，它能被吸收、反射或者透射。吸收的部分能量到达叶绿体，引发了光合作用，在这个过程中，辐射能被用于转化水和二氧化碳成为糖。
太阳辐射包含了不同波长的光谱。然而，仅有一个有限的光谱带对光合作用是有效的。这就是光合活性辐射（PAR）带，对绿化植物是位于380nm到710nm之间。
Measurement of photosynthesis
The rate of photosynthesis is a gross measurement of the rate at which a plant captures radiant energy and fixes it into carbon compounds,Net assimilation is the difference between photosynthetic assimilation and losses due to respiration,Therefore,not assimilation will be negative in the dark and will increase with increasing PAR,The intensity of PAR at which the gain in photosynthesis equals the losses is known as the compensation point.
光合作用的测量光合作用速率是总速率的测量，即植物捕获的辐射能，并把它固定到碳的化合物中。光合作用净同化是同化量的呼吸的丢失量之差。因此，净同化在黑暗中是负值，并随PRA增加而增长。在光合作用的同化量等于呼吸消耗量时的PRA强度，称为补偿点（compensation point）
植物的光补偿点示意图(Emberlin,1983)
光补偿点 (compensation point)光饱和点(saturate point)
光合作用强度和呼吸作用强度相当处的光强度为光补偿点；当光照强度达到一定水平后，光合产物不再增加或增加得很少，该处的光强度即为光饱和点。
Changes in the intensity of radiation
Plants rarely achieve their full photosynthetic potential,due to water shortage and to variation in the intensity of radiation,The systematic variations in light intensity are spatial and temporal of solar radiation,Less systematic variations in light intensity are caused by the positioning of leaves in relation to each other.
辐射强度的变化植物很难获得它们完全的光合作用潜能，是由于水短缺和辐射强度的改变。光强度的系统变化是太阳辐射的空间和时间的差异。光强度中极少部分的系统变化是因叶子彼此的相对位置引起。
太阳高度角不同，射程不同，太阳辐射强度不同
C3 and C4 plants
A major difference in the photosynthetic capacity of plants is that between C3and C4 plants,C4 plants are able to capture CO2 with greater water use efficiency than C3 plants,but this advantage comes at an energy cost,In C4 plants the rate of photosynthesis increases with light intensity,whilst photosynthesis tails off with increasing light intensity in C3 plants,
C3和C4植物植物光合能力中的主要差别是在C3和C4植物之间。C4植物能捕获CO2,伴随着水的利用效率比C3植物更大，而这优点需要消耗能量。在C4植物中，光合作用率随光强度而增加，而C3植物随光强度增加光合作用渐渐减小。
Strategic and tactical response of plants to radiation
A major strategic difference between plant species in their response to the intensity of radiation is exhibited by ‘sun species’ and ‘shade species’,which possess a range of adaptations to high and low light levels,respectively,Also,plants may grow leaves which develop differently under different light conditions as part of a tactical response to the light environment,This is most clearly seen in the formation of sun leaves and shade leaves within a leaf canopy of single plant.
植物对辐射的战略和战术响应植物种间对辐射强度反应的主要战略差异显示为“阳地种”和“阴地种”，它们分别具有适应于高的和低的光辐射范围。同样，植物能够在不同光条件下生长不同的叶子，作为对光环境的部分战术反应。这一点最清楚地在单株植物叶冠内的阳叶和阴叶的结构上看到。
1）阳地植物/阳生植物:在强光照下才能正常生长、发育，而在隐蔽条件和弱光条件下生长不良的植物。如松、杉、杨、柳、麻栎、栓皮栎、桦、槐等。
2）阴地植物/阴生植物:在弱光照下比在强光照下生长良好的植物。如人参、三七、红豆杉、云杉、冷杉、翠云草、半夏、细辛等。
阴地植物与阳地植物对光照强度的适应


动物对光照强度的适应有些动物适应于白天的强光照下活动，称为昼行性动物。
因其能忍受的光照范围较广，故又称为广光性动物。
有些动物适应于在夜晚或晨昏的弱光下活动，则称为夜行性动物或晨昏性动物。
因其只适应于在狭小的光照范围内活动，所以又称为狭光性动物。
生物对光周期的适应植物的开花结果、落叶及休眠，动物的繁殖、冬眠、迁徙和换毛换羽等，是对日照长短的规律性变化的反应，称为光周期现象
1、植物的光周期,
2、动物的光周期
1、植物的光周期根据对日照长度的反应类型可把植物分为：
长日照植物：只有当日照长度超过它的临界日长时才能开花的植物，否则，只有营养生长，没有生殖生长。如冬小麦、大麦、油菜、菠菜、萝卜等。起源于北方。
短日照植物：只有当日照长度短于临界日长时才能开花的植物。这类植物通常在早春或深秋开花。如苍耳、水稻、玉米、大豆、烟草、麻、棉。这类植物通常在早春或深秋开花。起源于南方。
中日照植物：是指当昼夜长短近于相等时才能开花的植物。如黄瓜、番茄、番薯、四季豆、蒲公英中间型植物：这类植物对日照长度的要求不严，只要其他条件合适，在不同的日照长度下都能开花。
动物的光周期现象
（1）繁殖的光周期现象：
长日照动物和短日照动物：在温带和高纬度地区许多鸟兽在春夏之际白昼逐渐延长的季节繁殖后代，称长日照动物；与些相反，一些动物只有在白昼逐步缩短的秋冬之际才开始性腺发育和进行繁殖，称短日照动物。前者如雪貂、野兔、刺猬；后者如绵羊、山羊和鹿等。
（2）昆虫滞育的光周期现象：很多昆虫在它们生命周期的正常活动中，能插入一个休眠相，即滞育，常由光周期决定的。
（3）换毛与换羽的光周期现象：温带和寒带地区，鸟兽的换毛换羽
（4）动物迁移的光周期现象：鸟类的长距离迁徙，鱼类的回游五、TEMPERATURE
Ecological Effects of temperature
The rate of an enzyme catalyzed reaction increases with temperature,The temperature coefficient (Q10) is an index of the effect of a 10℃ temperature rise on metabolic rate,and is often near 2.0,Within the nonlethal temperature range the most important effect on organism of temperature is likely to be its effect on growth and development,
温度的生态作用酶催化反应的速度随温度而增加（温度系数（Q 10) 是温度升高10℃对代谢速度影响的指数，经常大约为2.0）在非致死温度范围内，温度对生物最大的影响很可能是影响了生长和发育。
温度与生物生长
-“三基点”：对应于酶活性的最低、最适和最高温度
-不同生物的“三基点”不一样温度与生物发育
-有效积温法则
-春化
有效积温法则有效积温法则:生物在生长发育过程中必须从环境中摄取一定的热量才能完成某一阶段的发育，而且植物各个发育阶段所需的总热量是一个常数。
K=（T-T0）N T0为物理学0℃—活动积温
K=（T-C）N C生物学0℃（发育起点温度）——有效积温有效积温法则的实际应用预测生物（特别是病虫害）发生的世代数；
预测生物地理分布的北界；
预测害虫来年的发生程度；
推算生物的年发生历；
根据积温制定农业气候区划，合理安排农业生产
Vernalization and Acclimation
Temperature may also act as a stimulus,determining whether the organisms will begin development,Vernalization is the induction of flowering by low temperatures,Exposure of an organism to higher (or lower) temperatuers in the laboratory can alter the organisms temperature response,The habituation of an organism’s response to changes in laboratory environmental conditions is termed acclimation,Acclimatization is the habituation of an organism’s physiological response to changes in natural environmental conditions.
春化和驯化温度能够作为一种刺激物起作用，决定有机体是否将开始发育。春化法是通过低温诱导开花。有机体在实验室里暴露到较高（或较低）的温度能够改变有机体的温度反应。有机体对实验环境条件变化产生的适应性反应称为驯化（acclimation）。有机体对自然环境条件变化产生的生理适应性反应称为气候驯化（acclimatization）。
Temperature thresholds
High temperatures may lead to enzyme inactivation or the unbalancing of components of metabolism; for example,in plants,respiration may proceed faster than photosynthesis,leading to death,however,the most frequent effect of high temperature on organism is dehydration,All terrestrial organism must conserve water but at high temperatures rates of water loss can be lethal,
There are large differences between the low temperature tolerances of differing species,associated with the processes of freezing,chilling and hardening,Many are killed by temperatures below –1℃ due to the damaging effects of ice-crystal formation within cells.
温 度 阈高温可能导致酶失活或代谢组分不平衡，例如植物的呼吸作用快于光合作用而导致死亡。然而高温对生物最普遍的影响是引起脱水。所有陆生生物必须保持水，但在高温下失水率能够成为致死因子。
不同物种对低温的耐受性有很大的差异，这与结冰、寒冷和坚硬的过程有关。温度低于-1℃时很多物种被冻死，这是由于细胞内冰晶形成的损伤效应生物对低温的适应植物
形态结构：油脂、鳞片、短小、匍匐状，厚皮
生理适应：减少细胞内的水分，增加糖类、脂肪和色素动物
形态：阿仑规律、贝格曼规律、毛、皮结构、脂肪层
生理：基础代谢和非颤抖性产热(褐色脂肪)，
行为：迁徙、冬眠、冬睡、滞育、集群、活动位置
Allen’s rule
The effects of temperature on individuals may be moderated by evolved differences,Allen’s rule states that endothermic animals from cold climates tend to have shorter extremities (ears and legs) compared with animals from warmer climates,thus reducing their surface area,volume ratio,This rule has widespread applicability,
阿伦法则阿伦法则（Allen’s rule）陈述了来自冷气候中的内温动物与来自温暖气候的内温动物相比，趋向于具有更短的末端（耳朵和四肢）；因此降低了它们的表面积对体积的比率。
Bergmann’s rule states that mammals tend to be larger in colder areas than warm climates,again to reduce their surface area,volume ratio.,
贝格曼规律贝格曼规律（Bergmann’s rule）讲述了寒冷地区的哺乳动物比温暖地区的哺乳动物个体趋向于更大，也减低了它们的表面积与体积的比率。
生物对高温的适应植物
形态适应：叶片毛、鳞片、颜色、排列 木栓层生理适应：细胞含水量(糖/盐浓度、代谢强度) 旺盛的蒸腾作用动物
生理适应：适当放松恒温性行为适应：栖居地点、活动时间本 章 小 结光照和温度的时空变化规律
光质、光强、光周期对生物的影响
生物对光质、光强、光周期的适应温度的生态作用，极端温度对生物的影响
生物对极端低温、极端高温的影响
主要概念
春化、光饱和点、光补偿点、阴地植物、阳地植物、长日照植物、短日照植物、长日照动物、短日照动物、温度三基点、有效积温、贝格曼规律、阿仑规律、休眠思考题
1,光在时空上的配置对植物和动物产生哪些影响？它们又是如何适应这些变化的？
2,低温和高温对生物会产生哪些影响?为什么温度能够限制生物的分布?
3,生物是如何适应极端温度条件的？
4,在引种驯化中应该注意光照和温度的哪些因素？
六、Organism and Water
（一）水因子的生态作用
1、水是生物生存的重要条件
2、水对动植物生长发育的影响
3、水对动植物数量和分布的影响生物体的水分获得与损失途径水分的丧失途径植物－蒸发（蒸腾作用、扩散作用）失水，分泌失水。
动物－蒸发失水，排泄、分泌失水。
水分获得途径植物－－根部吸收，叶面吸收。
动物－－食物，体表吸收，代谢水。
（二）生物对水因子的适应
1、植物对水因子的适应
陆生植物,湿生植物、中生植物、旱生植物（少浆液、多浆液植物）
水生植物：沉水植物、浮水植物、挺水植物
在形态、生理、结构上的不同适应
2、动物对水因子的适应
水生动物的渗透压调节
两栖类动物对环境湿度的适应
陆生动物对环境湿度的适应
Soil water
For terrestrial plants the main source of water is the soil,which serves as a reservoir.,water enters the reservoir as rain or melting snow and passes into the soil pores,The upper limit of the water-holding capacity of a soil is called the field capacity,This is the amount of water which can be held by soil pores against the force of gravity.
Plants cannot extract all the water held in the soil,as they cannot exert sufficient suction force to extract water from the narrower soil pores,The lower limit of water availability is thus determined by the physiology of the plant species and is known as the permanent wilting point – the soil water content at which plants wilt and are unable to recover.
土 壤 水对于陆地植物，水的主要来源是土壤，它起了蓄水池的作用。当下雨或雪融化时，水进入蓄水池，并流进孔隙。土壤的水容量上限称为田间持水量（field cap-acity）。这是土壤孔隙抗地心引力所储蓄的水量。
植物不能吸取土壤中储蓄的全部水，因为它们不能产生足够的吸力从更细的土壤孔隙中吸水。因此可利用水的下限是由植物物种的生理特性所决定的，被称为永久萎蔫点（permanent wilting point）——土壤水（soil water）含量在这个点上，植物枯死，不能恢复。
The uptake of water by roots
Roots can capture water from the soil in two ways,either water may move through the soil towards a root or the root may grow through the soil towards the water,As a root withdraws water from the soil capillary pores at its surface,it creates water depletion zones around it,If a root draws water from the soil very rapidly,the resource depletion zone (EDZ) will receive water from the surrounding soil at a slow rate,restricting water availability,so plants may wilt even in soil containing abundant water.
根对水的吸收根以两种方式从土壤中捕获水：要么水穿过土壤向根移动，要么根生长穿过土壤向水移动。当根以它的表面从土壤毛细管孔隙吸水时，在根的周围产生了水耗竭区。如果根从土壤中吸水很快，资源耗竭区（RDZ）将以一个低速率从周围土壤中接收水，从而限制了水的可利用性，使植物即使在含水丰富的土壤中也可能枯萎。
Aquatic plants and water
Water is apparently available in aquatic environments,However,the osmotic regulation of internal fluids can be energetically expensive,especially in saline environments,The salinity of an aquatic environment and of terrestrial habitats bordering the sea has an important influence on plant distribution and abundance,Plants which grow in high salinity,halophytes,accumulate electrolytes in their vacuoles,but the concentration in the cytoplasm and organelles is kept low.
水生植物和水在水环境中，水显然是随意可利用的。然而，内部体液的渗透压调节可能消耗能量，特别是在盐水环境中。水环境的盐度与沿海陆地栖息地的盐度，对植物分布移度有重要的影响。生长在高盐度中的植物，即盐生植物，它们的液泡中累积了电解质，但在细胞质和细胞器官中保持着低浓度。
Water availability and plant productivity
Precipitation is a key determinant of plant productivity in forests,whilst in arid regions there is an approximately linear increase in primary productivity with increasing precipitation,The amount of water that would be transpired from a site,assuming no soil water limitation and complete vegetation cover is the potential evapotranspiration rate,The difference between this index and the precipitation rate defines whether the environment is moist or arid,
水的可利用性与植物生产力降雨量是森林植物生产量的关键决定因子，而在干旱地区，初级生产量随降雨量的增加大致呈一个线形增长。假设一个地区没有土壤的水限制，并完全地被植物覆盖，水从这个地区的蒸发量就是潜在蒸发蒸腾速度（potential evapotranspiration rate）。这个指标和降雨量之间的差异决定了环境是潮湿的，还是干旱的。
Water balance in fish
Maintaining water balance is problematic in an aquatic environment,which is countered by osmoregulatory mechanisms,Freshwater fish have to continually excrete excess water because the fish is hypertonic relative to its surroundings (the concentration of solutes in body fluids is higher than the solute concentration of the water),and they produce a large volume of very dilute urine.
Bony fishes living in seawater have the opposite problem,being hypotonic to their surroundings,The kidneys of marine fish secrete very little urine,and instead function mainly as a means of removal of divalent ions such as Ca2+,Mg2+and SO42-.
鱼类的水平衡在水环境中保持水平衡是有疑问的，它是通过渗透调节机制解决的。淡水鱼必须连续地排泄过量的水，因为鱼与它的环境相比，它是高渗透性的（体液的溶质浓度比水的溶质浓度高），它们产生大量的低浓度的尿。
生活在海水中的硬骨鱼有相反的问题，它们要的功能是去除两价的离子，如像Ca 2+、Mg 2+ 和SO42-
等渗（isosmotic organism）
体内和体外的渗透压相等，水和盐以大致相等的速度在体内外之间扩散。仅排泄失水，通过食物、饮水、代谢水获得水，泌盐器官排出多余的盐分。
高渗（hyperosmotic organism）
体内的渗透压高于体外，水由环境中向体内扩散，体内的盐分向外扩散。通过排泄作用排出多余的水，盐分通过食物和组织摄入。
低渗（hypoosmotic organism）
体内渗透压低于体外，水分向外扩散，盐分进入体内。通过食物、代谢水和饮水获得水，多种多样的泌盐组织排出多余的盐分。
淡水鱼类生活的环境是一种特殊的低盐环境，淡水硬骨鱼类血液和体液的渗透压高于水的渗透压，进入体内多余的水通过鱼的肾脏排除大量低浓度尿，通过食物和鳃主动吸收盐离子，保持水盐代谢的平衡。
海洋硬骨鱼类的血液和体液大大低于海水的渗透浓度，如鲱、鲑等。因此保持水分平衡的有效方法是大量饮水；通过细胞膜上具有Na+泵和K+泵，主动排盐。
Water balance in amphibians
Amphibian kidneys function much like those of freshwater fishes.However,on land,where dehydration is the most important problem in terms of osmoregulation,frogs conserve body fluid by reabsorbing water across the epithelium of the urinary bladder.
两栖类的水平衡两栖类的肾功能很像淡水鱼的肾功能。然而在陆地上，脱水对渗透调节是最重要的问题，蛙保存体液是通过膀胱上皮细胞的重吸收水。
Water conservation by terrestrial animals
A major problem faced by terrestrial organisms is the loss of a continuous supply of water necessary to keep tissue surfaces moist.When air is inhaled,it passes along the respiratory tract into the lungs,where it is in contact with the moist respiratory tissues.If the moist air was exhaled,water would be lost,
The recovery of respiratory moisture by most terrestrial animals involves countercurrent exchange,Exhaled air from the lungs encounters a countercurrent-like gradient on the way out,This interaction between the departing air and the respiratory surfaces results in an efficient return of moisture to the tissues.
陆生动物的水保持陆生动物面对的主要问题是连续地失水，这是供应到组织表面维持潮湿所必需的水。当空气被吸入时，它沿着呼吸道进入肺，和潮湿的呼吸组织相接触。如果潮湿的空气被呼出，水就会丢失。
大多数陆生动物呼吸湿度的维持包括了逆流交换（countercurrent exchange）从肺呼出的气体，在呼出的通道上有一个像逆流的梯度。呼出的气体和呼吸表面的相互作用，导致水分有效地返回组织。
Water conservation by mammalian kidneys
The water-conserving ability of the mammalian kidney represents a key terrestrial adaptation,Water recovery from the urine before it leaves the kidney takes place in the loop of Henle.
Mammals adapted to the desert (such as kangaroo rats) that excrete highly concentrated hypertonic urine,have exceptionally long loops of Henle,In contrast,beavers,which spend much of their time in fresh water,have nephrons with very’short loops,resulting in dilute urine,The kidneys of reptiles are less sophisticated and produce urine that is,at best,isotonic to body fluids,This means that the solute concentration of urine is equal to the solute concentration of the body fluids.
哺乳动物肾脏的水保持哺乳动物肾脏的水保存能力表现出关键的陆生适应性。尿离开肾脏之前，水在亨利氏袢中被回收。
适应于荒漠的哺乳动物，如更格卢鼠，排泄高浓度的高渗尿，它们有极长的亨利氏袢。相反，河狸大部分时间是在淡水中渡过的，它们的肾单位具有很短的袢，产生低浓度的尿。爬行动物的肾脏结构较简单，产生的尿最多也就是与体液等渗。这意味着，尿的溶质浓度与体液的溶质浓度是相等的。
形态结构适应
昆虫具有几丁质的体壁，防止水分的过量蒸发；两栖类动物体表分泌粘液以保持湿润；哺乳动物有皮质腺和毛，防止体内水分过多蒸发。
行为的适应
沙漠动物昼伏夜出：沙漠地区夏季昼夜地表温度相差很大，因此地面和地下的相对湿度和蒸发力相差很大
迁徙：在水分和食物不足时，迁移到别处。
POPULATIONS AND POPULATION STRUCTURE
Population
A population is a group of organisms of the same species which occupies a given area,The boundaries between populations can be arbitrary,
种 群种群是一定区域内同种生物个体的集合。种群间的边界可以是任意的。
自然种群的基本特征空间特征：种群具有一定的分布区域
数量特征：每单位面积(或空间)上的个体数量(即密度)及变动
遗传特征：种群具有一定的基因组成个体可能呈随机、均匀和聚集分布格局 (方差/平均数比)
均匀分布：S2/m=0--原因：种群内个体间的竞争。
随机分布：S2/m=1--原因：资源分布均匀，种群内个体间没有彼此吸引或排斥。
聚集分布：S2/m>1--原因：资源分布不均匀；种子植物以母株为扩散中心；动物的社会行为使其结群。
方差/平均数比率：S2/m
S2=[Σ(fx)2-(Σfx)2/n]/(n-1)
m=Σfx/n
x—样方中某种个体数
f—含x个体样方中出现频率
n—样方总数
Populations may be categorized as consisting of either unitary or modular organisms,In unitary populations,each zygote gives rise to a single individual,In modular organisms,the zygote develops into a unit of construction which gives rise to further modules and a branching structure,The structure may then fragment producing many individual ramets.
种群可以根据组成种群的生物是单体生物还是构件生物进行分类。在单体生物种群中，每一受精卵发育成一单个个体。在构件生物种群中，受精卵发育成一个结构单位，这一结构单位再形成更多的构件和分支结构。然后这些结构可能分裂，形成许多无性系分株。
Population size
The population size for unitary organisms,such as mammals,is simply the number of individuals in a given area,For modular organisms,such as plants and corals,The situation is more complex,In this case the number of ‘pieces’ (ramets) or the number of shoots (modules) may give a more meaningful indication of abundance than the number of different individuals.
种群大小对于单体生物和种群如哺乳类，其种群大小就是一定区域内个体的数量，非常简单。对于构件生物，如植物和珊瑚，情况就较复杂。对于这些种群，“断片”（无性系分株）或枝条（构件）的数目比不同个体的数量更有意义代表多度。
Age and stage structure
The age structure of a population is the number of individuals in each age class expressed as a ratio,and is usually displayed as an age pyramid diagram,A population which is neither expanding nor contracting will have a stationary age distribution,A growing population will have more young,While a declining population will be dominated by older age classes,
年龄和时期结构种群的年龄结构是每一年龄阶段个体数目的比率，通常以年龄金字塔图来表示。既不增长也不下降的种群有稳定的年龄分布。增长型的种群有更多的年轻个体，而在下降型种群中年老的个体占优势。


Where organisms pass through discrete growth stages (e.g,insect larval instars),the number of individuals at each stage (the ‘stage structure’) may provide a useful description of the population,In species where growth rates are indeterminant (such as plants),size classes may be more informative.
当种群经历离散和发育时期（如昆虫的龄期）时，每一时期个体的数目（“时期结构”）可以对种群进行有效的描述。对于生长率无法预测的物种（如植物），根据大小分类可能更有意义。
NATALITY,MORTALITY AND POPULATION GROWTH
Natality
Natality is the birth of new individuals,The realized natality is the actual successful reproduction per female over a period of time,The age-specific birthrate is the number of offspring produced per unit time by females in specific age classes,
出 生 率出生率就是新个体的产生，实际出生率就是一段时间内每个雌体实际的成功繁殖量。特定年龄出生率就是特定年龄组内雌体在单位时间内产生的后代数量。
mortality
The death rate,or mortality rate,is the number of individuals dying during a given time interval divided by the average population size over that time interval,This is an instantaneous rate and be estimated for the population as a whole or for specific age classes to give the age specific mortality rate,The probability of dying is the number dying per individual present at the start of the time period.
死 亡 率死亡率是在一定时间段内死亡个体的数量除以该时间段内种群的平均大小。这是一个瞬时率，可用来估价整个种群的死亡率或特定年龄群的特定年龄死亡率，死亡的概率是死亡个体数除以在每一时间段开始时的个体数。
Survivorship
Survivorship is the converse of mortality,Survivorship data are often shown as a survivorship curve for a particular population; a graph showing the proportion of survivors on a logarithmic scale through each phase of life,
存 活 率存活率是死亡率的倒数。对于一个特定种群，存活率的数据通常以存活曲线的形式来表示；存活曲线表示的是在每一个生活期存活个体所占的比率的对数值。
There are three generalized patterns of age-specific survivorship depending on whether the probability of dying is highest later in life (Type I),constant through life (Type II) or highest for young stages (Type III).
根据各种生活期死亡率的高低，特定年龄存活曲线一般有三种模式：后期死亡率最高（类型I），各期死亡率相等（类型II），早期死亡率最高（类型III）。
Life Table
(1) Definition of life table
(2) Types of life table
(3) Excellences of life table
一、生命表的定义
生命表是按种群生长的时间,或按种群的年龄(发育阶段)的程序编制的,系统记述了种群的死亡或生存率和生殖率,是最清楚、最直接地展示种群死亡和存活过程的一览表.
最初用于人寿保险,对研究人口现象和人口的生命过程有重要的意义.
Dynamic and static life tables
Dynamic life tables summarize the fate of a group of individuals born at approximately the same time from birth to the end of the life cycle,Such a group is known as a cohort and investigation of this kind is termed cohort analysis,Static life tables summarize the age structure born at special time.
动态和静态生命表动态生命表总结了一组出生时间大体相同的个体从出生到死亡的命运，这样的一组个体称为同生群，这样的调查称为同生群分析。静态生命表根据某一特定时间对种群作一年龄结构调查资料综合生命表：增加出生率生命表的主要优点
1,系统性,记录了从世代开始至结束.
2,阶段性,记录各阶段的生存或生殖情况.
3,综合性,记录了影响种群数量消长的各因素的作用状况.
4,关键性,分析其关键因素,找出主要因素和作用的主要阶段.
Life tables show the number of individuals present at different life stages or ages together with age-specific survival rates and age-specific mortality rates calculated for each stage,Mortality at each stage is expressed by k-values which are derived from logarithms and can be summed to give total mortality
生命表表示存在于不同生命阶段或年龄个体的数量，以及每一阶段的年龄特定存活率和年龄特定死亡率。每一阶段的死亡率用k值表示，k是通过对数函推导出来的，并且可以相加得出总死亡率。
k-Factor analysis
This technique allows the identification of key factors contributing to mortality,Stage-specific k-values obtained over successive years are compared to the values for total mortality (ktotal),K-Factor analysis highlights those stages suffering the greatest mortality which are responsible for fluctuations in loss rate and hence population size,
K-因子分析这一方法可以辩明关键因子对死亡率的作用。连续几年获得的特定阶段k值与总死亡率（k总）相比。K因子分析强调那些死亡率最高的阶段，这些阶段是种群丧失率和种群大小波动的关键。
The fecundity schedule
Fecundity is the number of eggs,seeds,or offspring in the first stage of the life cycle produced by an individual,The fecundity schedule allows the calculation of the basic reproductive rate R0,This is the number of offspring produced per original individual by the end of the cohort,In an annual population,it indicates the overall extent to which the population has increased or decreased over that time.
生殖力表生殖力是指同一个体生产的卵、种子或处于生活史第一阶段后代的数目。生殖力表可计算基础生殖率R0。R0是在同生群结束时每个亲体产生后代的数量。在一年生种群中，R0表示在这段时间内，种植增长或下降的总的程度。
population growth
The changes in population size over time can be calculated by adding birth (B) and the number of immigrants (I)to the original population at time t,(Nt ),and subtracting the number of deaths (D) and emigrants (E) to give a new population size an the time t+1(Nt+1),This is represented by the equation;
N t+1 = N t +B + I – D – E
种群增长种群大小随时间的变化可以按如下方法计算：t时间种群原来数量（Nt），加上新出生的个体数（B）和迁入个体数（I），减去死亡个体数（D）和迁出的个体数（E），就可得到t+1时间种群的数量（N t+1），这可用以下方程表示。
N t+1= Nt +B + I – D – E
For a particular set of conditions,an individual has a maximum potential for reproduction which is its intrinsic natural rate of increase,r,This is the theoretical maximum that may be reached in a given environment if the population is not resource-limited.
在一组特定条件下，一个体具有最大的生殖潜力，称为内禀自然增长率r。这是种群在不受资源限制的情况下，于一定环境中可达到的理论最大值。
r = lnR0/T （T – 世代时间）
种群的增长模型与密度无关的种群增长模型与密度有关的种群增长模型与密度无关的种群增长模型
种群在“无限”的环境中，即假定环境中的空间、
食物等资源是无限的，则种群就能发挥内禀增长能力，数量迅速增加
种群增长率不随种群本身的密度而变化，种群呈指数增长格局
Density-independent population growth
Unlimited growth of this kind is described by a continuous population model and expressed in terms of the rate of change in population numbers at time t:
Rate of change of population Size at time t = Intrinsic rate of increase × population size
dN/dt = rN
非密度制约性种群增长这种无限增长可用连续型种群模型来描述，以在t时间时，种群数量的变化率来表示：
t时间种群大小的变化率=内禀增长率×种群大小
dN/dt = rN
r>0种群上升；r=0种群稳定；r<0种群下降与密度有关的种群增长模型一、两点假设
（1）环境容纳量(K)：环境条件所容纳的种群最大值
（2）增长率随密度上升而降低的变化，是成比例的。每一个体利用空间为1/K，N个体利用N/K空间，剩余空间为1- N/K。
二、种群增长的S形曲线开始期：群大小N很小，密度增长缓慢加速期：随个体数增加，密度增长逐渐加快转折期：当N=1/2K时，种群密度增长最快减速期：当N>1/2K时，密度增长逐渐变慢饱和期,N= K，种群的增长为零，种群达到了一个稳定的大小不变的平衡状态。
四、逻辑斯谛方程
Density-dependent growth-the logistic equtation
The logistic equation describes the growth of a simple population in a confined space,where resources are not unlimited,In the early stages resources are abundant,the death rate is minimal and reproduction can take place as fast as possible allowing the individuals to attain their intrinsic rate of increase,The population increases geometrically until the maximum number of individuals the environment can sustainably support is approached,This maximum number is called the carrying capacity (K),The population growth rate declines to zero as the population becomes more crowded and the population size stabilizes,
密度制约性种群增长：
逻辑斯谛方程逻辑新谛方程描述的是一个在有限资源空间中的简单种群的增长。在早期，资源丰富，死亡率最小，繁殖尽可能的快，种群内个体可达到内禀增长率。种群呈几何式增长，直到种群数量达到环境可持续支持的最大程度，即环境容纳量（K）。当种群更加拥挤时，种群增长率减少到零，种群大小处于稳定状态。
This can be described as the logistic equation,
Rate of change of Intrinsic rate Population Density dependent
Population size at time t = of increase × size × factor
Dn/dt=rN(1-N/K)
Where the density-dependent factor,(1-N/K)approaches zero as the population approaches the carrying capacity and intraspecific competition becomes more intense,This equation predicts growth of a population over time to be sigmoidal,as is commonly observed in real populations,
这可用逻辑斯谛方程来表示：
T时间种群大小变化率=内禀增长率×种群大小×密度制约因子
dN/dt = rN(1 - (N/K))
当种群达到环境容纳量，种间竞争变得更激烈时，密度制约因子（1 - (N/K)）会接近零。该方程预测种群的增长随时间变化呈现出“S”形，如在真实种群中通常所观察的那样。
五、重要意义
-许多相互作用种群增长模型的基础
-确定鱼业、林业、农业等领域的最大持续产量
-r、K为生物进化对策理论中的重要概念
Equilibrium population density
The equilibrium population density occurs when the per capita death rate exactly balances the per capita birth rate such that the density is neither increasing nor decreasing,The equilibrium population density is equivalent to the carrying capacity K.
平衡种群密度当单位个体出生率正好平衡单位个体死亡率，种群密度既不增加也不减少时，此时的种群密度为平衡种群密度。平衡种群密度与环境容纳量K值相等。
POPULATION DYNAMICS – FLUCTUATIONS AND CYCLES
Expanding and contracting populations
Most real populations are not at their constant equilibrium density for very long,but are dynamic and changing,Populations may be expanding or contracting because of changes in environmental conditions or because of changes to their biotic environment.
增长种群和收缩种群大多数实际种群并不是在平衡密度停留很长时间，而是动态的不断的发生变化。由于周围环境的变化或生物因子的影响，种群可能会增长或收缩。
Populations fluctuations
Populations may fluctuate for a number of reasons:
A time lag between a change in density and its effect on the population size,or delayed density dependence,The population can overshoot the carrying capacity and then show gradually diminishing,dampened oscillations before eventually stabilizing at equilibrium.This delayed density dependence may also produce cycles in predator and prey abundance;
（ii） Overcompensating density dependence,This can lead to dampened oscillations,stable limit cycles (regular cycles that do not damp down) or chaotic fluctuations that appear random;
Environmental stochasticity,This is a nondeterministic,unpredictable variation in the environmental conditions,resulting in a changing equilibrium density.
种群波动种群波动可能有以下几个原因,（i）时滞或称为延缓的密度制约，存在于密度变化及其对种群大小的影响之间。种群可能超过环境容纳量，然后逐渐减少，在最终达到平衡之前呈现减幅振荡。这种延缓的密度制约可能使捕食者和猎物多度之间产生周期。
（ii）过度补偿性密度制约。其可能导致减幅振荡、稳定极限环（非减幅振荡的有规律周期变化）或无规则随机振荡。
（iii）环境随机变化。环境条件非确定性的、不可预见性的变化会导致平衡密度的变化。
种群调节气候学派
-气候学派多以昆虫为研究对象
-种群参数受气候条件强烈影响，种群增长主,要受有利气候时间短暂的限制
-种群没有时间达到环境容量所容许的数量水平，无食物竞争
-强调种群数量的变动，否定稳定性生物学派主张捕食、寄生、竞争等过程对种群调节的决定作用
-只有密度制约因子才能调节种群的密度
-食物对种群调节的重要作用
-气候学派和生物学派的折中：适于不同的环境条件行为调节
-种内个体间通过行为相容与否调节其种群动态结构的一种方式
-领域性：指由个体、家庭或其他社群单位所占据的，并积极保卫不让同种其他成员侵入的空间。保卫领域方式：鸣叫、气体标志、威胁、直接进攻驱赶入侵者
-社群等级：动物种群种各个动物的地位具有一定顺序的等级现象。通过社群行为，可以限制生境中的动物数量内分泌调节
-种群数量上升时，种内个体经受的社群压力增加，加强了对中枢神经系统的刺激，影响了脑垂体和肾上腺的功能，使促生殖激素分泌减少(使生长和生殖发生障碍)和促肾上腺皮质激素增加(机体的抵抗力可能下降)，这种生理反馈机制使种群增长受到停止或抑制，社群压力降低
-主要适用于兽类遗传调节
-种群数量可通过自然选择压力和遗传组成的改变得到调节
-种群内的遗传多型是遗传调节的基础
-不同遗传结构的个体其生存能力不同
-遗传与生物的行为、扩散等因素一起对种群数量进行调节
INTERSPECIFIC AND INTRASPECIFIC INTERACTIONS
Classifying interactions
Interactions between individuals and species can be classified on the basis of the effects and the mechanism of the interaction,The key interspecific interactions are competition,predation,parasitism and mutualism,whilst the main intraspecific interactions are competition,cannibalism and altruism.
相互作用的分类个体或物种间的相互作用可以相互作用的机制和影响为基础来分类。关键的种间相互作用是竞争、捕食、寄生和互利共生，而主要的种内相互作用是竞争、自相残杀和利他主义。
Interspecific Competition
Interspecific competition occurs between two species using the same limited resource,Guilds are groups of species that occupy similar niches ; for example,insects feeding on broad-leaved trees form one guild,Very few species can escape from the effects of other species competing for the same resource.
种间竞争种间竞争发生在利用同样有限资源的两物种之间。占据相似生态位的物种组合的集团称为同资源种团；如以阔叶树为食物的许多昆虫就形成一个同资源种团。极少种能够逃脱其他种与之竞争共同资源的影响。
Competitive exclusion
If two species compete in a stable environment,there are two possible outcomes; (i) one species is excluded,or (ii) both species coexist (Gause hypothesis),The competitive exclusion principle states that coexistence can only occur in a stable environment if the species niches are differentiated.
竞争排斥如果两个物种在稳定环境中竞争，则有两种可能的结果：（i）一种被排除，或（ii）两种共存（高斯假说）。竞争排斥原理陈述，共存只能发生在两物种生态位分化的稳定环境中。
Limiting similarity
How much niche differentiation is needed for species to coexist? This critical threshold of differentiation in resource utilization is termed the limiting similarity,Ii is determined by the balance between intraspecific competition and interspecific competition.
极限相似性共存各需要多少生态位分化？在资源利用分化上的临界阈值叫做极限相似性。极限相似性决定于种内竞争强度和种间竞争强度之间的平衡。
Exploitation Competition
There are two ways in which competition can operate,In exploitation competition,individuals only interact indirectly,by depleting the resource in short supply,Reduced fitness occurs due to a shortfall in resource availability.
利用性竞争竞争有两种作用方式。在资源利用性竞争方式下，个体不直接相互作用，而是耗尽资源使供应不足。由于可利用资源不足而造成适合度下降。
Interfernce Competition
In interference competition,individuals interact directly,most obviously,in the case of some animal species,by fighting,but also by producing toxins (e.g,plant allelopathy),Fitness reduction in the ‘loser’ in such interactions may be due to the interference (e.e,injuries or death) as well as the lack of resource access.
干扰性竞争在干扰性竞争方式下，个体直接相互作用，在一些动物种类中，最明显的通过打斗，也通过产生毒物（如植物异株克生）进行竞争。在这种相互作用中“败者”适合度下降，可能由于干扰（如受伤或死亡），也或许由于缺乏可用资源。
Asymmetry in the effects of Competition
Competition often unevenly affects competitors,such that the cost for one individual is far greater than for another,It is common for competition to kill the losers,either via exploitation or interference.
竞争结果的不对称竞争通常不均等的影响竞争者，一个体的竞争代价远高于另一个体。竞争杀死失败者是很普遍的，或通过掠夺资源或通过干扰。
Lotka-Volterra模型假设两个物种，单独生长时增长曲线为逻辑斯蒂模型
若将两个物种放在一起，他们发生竞争，从而影响其他种群增长,
假设α12表示在物种1的环境中，每存在一个物种2的个体，对于物种1的效应。 α21表示在物种2的环境中，每存在一个物种1的个体，对于物种2的效应，则有逻辑斯蒂方程,
dN1 /dt = r1N1 (1-N1/K1 – α12N2/K1)
dN2 /dt = r2N2 (1-N2/K2 – α21N1/K2）
K1>K2/α21,K1/α12> K2，物种2被排斥，物种1取胜
K1<K2/ α21,K1/ α12 <K2，物种1被排斥，物种2 取胜
K1>K2/ α21,K1/ α12 <K2，不稳定的平衡点，两种可能获胜
K1<K2/ α21,K1/ α12 >K2,稳定的平衡点，两种共存
Competitive release
In the absence of a competitor,a species may expand its niche,Examples of such competitive release include ground doves in New Guinea and gerbils in Israel.
竞争释放在缺乏竞争者时，物种会扩张其实际生态位。这种竞争释放的例子包括新几内亚岛上的地鸽子和以色列的沙鼠。
Character displacement
When realized niches contract under the influence of competition,morphological changes may follow as adaptations to the new resource spectrum,Such character displacement is found in the ant Veromessor pergandei and in Darwin’s finches,Geospiza fortis and G,fuliginosa.
性状替换当明确的生态位契约受到竞争影响时，为了适应新的资源谱，个体形态会相应变化。这种性状替换发现在收获蚁Veromessor Pergandei 和达尔文雀，Geospiza fortis和G,fuliginosa。
Apparent competition
If a predator attacks two prey species,then each prey species may adversely affect the other,by increasing the local predator population,Therefore,the interaction between the two prey species is exactly as if they were competing,yet they may utilize entirely different resources,This phenomena is known as apparent competition.
表观竞争如果捕食者进攻两种猎物，那么每一种猎物，会通过增加当地捕食者种群的数量，相反地影响另一种。因此，两个猎物种群之间的相互作用看上去似乎它们确实是在竞争，然而它们或许利用完全不同的资源。这一现象叫做表观竞争。
他感作用他感作用 (allelopathy)
植物体通过向体外分泌代谢过程中的化学物质，对其他植物产生直接或间接影响的现象
存在于种内和种间
克生物质
乙烯、香精油、酚及其衍生物，不饱和内脂,生物碱、配糖体等
生态意义
对农林业生产的影响：歇地形象
影响植物群落的种类组成
植物群落演替的重要内在因素
THE NATUES OF PREDATION
Defining predation
Predation can be defined as the consumption of all or part of another individual (the prey),This wide definition thus encompasses,(I)’true predators’,which kill their prey soon after attacking them; (ii) grazers,which consume only part of a prey individual; (iii)parasites,which live in very close association with a single prey individual (the host),often inside the host’s tissues.
捕食的定义捕食可定义为摄取其他个体（猎物）的全部或部分为食。这一广泛的定义包括（i）典型的捕食者，在袭击猎物后迅速杀死而食之；（ii）草食者，只消费对象个体的一部分；（iii）寄生者，与单一对象个体（寄生）有密切关系，通常生活在寄主的组织中。
Carnivores and herbivores
Predators can be categorized as (i) herbivores which consume plant tissue,(ii) carnivores which food in animal tissue and (iii) omnivores which feed on both,The difference between animals and plants as prey types required different physiological and behavioral adaptations,and has lead to repeated evolutionary divergence between carnivorous and herbivorous lineages.
肉食者和草食者捕食者可以划分为（i）消费植物组织的草食者，（ii）摄食动物组织的肉食者和（iii）既摄食植物组织也摄食动物组织的杂食者。动物、植物食性的差异需要不同的生理和行为适应，从而导致肉食者与草食者世系之间反复的进行分歧。
Generalists and specialists
Predators vary in the number of species of prey they will feed on,with some species being specialists,whilst others are more generalist,Generally,parasites tend to be more specialist than true predators and herbivores tend to be more specialist than carnivores.
泛化种和特化种捕食者随其摄取猎物的数量多少而变化，某些捕食者是特化种，而另一些是泛化种。一般来说，寄生者比典型捕食者更为特化、而草食者比肉食者更为特化。
The impact of predators on prey population size
Do predators and parasites regulate the population size of their prey? This is not as simple question as it may appear,There are two main issues,(I) the effect of any one predator may only be a small component of the total mortality causes affecting a prey species,so removal of the predator will have only a minor effect;
(ii) predation may kill animals which were going to die anyway,so there will be no impact on the final prey population size,However,in a number of cases there is clear evidence that predators have a considerable impact on prey numbers.
捕食者对猎物种群大小的影响捕食者和寄生者是否能够调节其猎物种群的大小呢？这一问题并不像看上去的那么简单。有两种主要观点：（i）任一捕食者的作用，只占猎物种总死亡率的很小一部分，因此去除捕食者对猎物种仅有微弱效果；
（ii）捕食者只是杀死了对象种中即将死亡的个体，所以最终对猎物种群大小没有影响。然而，在一些例子中确有明显证据表明捕食者对猎物数量有重要影响。
Lotka-Volterra predator-prey model
The Lotka_Volterra predator-prey model is a simple mathematical model representing the interaction between predators and their prey,It makes three simplifying assumptions,(i) there is only one predator and one prey species involved in the interaction; (ii) prey numbers increase if the number of predators falls below a threshold and decrease if there are more predators;
(iii) predator numbers increase if the number of prey rises above a threshold and decrease if there are fewer prey,This simple model makes an interesting prediction,predator and prey populations will tend to cycle,as is observed in natural predator-prey dynamics.
Lotka-Volerra捕食者-猎物模型
Lotka-Volterra捕食者-猎物模型是描述捕食者与猎物间相互关系的一个简单的数学模型。这一模型做了三个简单化假设：（i）相互关系中仅有一种捕食者与一种猎物；（ii）如果捕食者数量下降到某一阈值以下，猎物数量就上升，而捕食者数量如果增多，猎物种数量就下降和
（iii）如果猎物数量上升到某一阈值，捕食者数量就增多，而猎物种数量如果很少，捕食者数量就下降。这一简单的模型做了一个有趣的预测：捕食者和猎物种群动态会发生循环，就像在自然的捕食者-猎物种群动态中所观察到的那样。
PREDATOR-PREY RELATIONSHIPS
Population cycles of snowshoe hares and their lynx predators based on the numbers of pelts received by the udson Bay Company
PREDATOR BEHAVIOR AND PREY RESPONSE
Profitability of prey
Given a choice between two potential prey types,a predator which is optimizing its effort should choose the most profitable prey,Evidence from common shore crabs and pied wagtails demonstrates that prey of a size which return the greatest energy reward per unit time are preferred over smaller and larger individuals.
猎物收益率面对两种类型猎物的选择时，捕食者要获得最佳捕获努力，就应该选择收益最大的猎物。真蟹和白脊令的证据表明捕食者优先选择能使其在单位时间内获得最大能量的一定大小的猎物，而不是比该体积更大或更小的猎物。
The effect of prey density – functional responses
It is generally expected that at high densities of prey,a predator’s consumption rate will increase and then flatten out as prey saturation occurs,this relationship is termed the functional response and may adopt different patterns,which can be stereotyped into three classes,functional responses I,II and III.
猎物密度影响——功能反应一般认为在高猎物密度下，捕食者的摄食率会增加，然后随猎物饱和达到最大速度。这种关系称为功能反应，可能采用多种模式，传统上分为三种类型：功能反应I、II和III。
功能反应Ⅰ：捕食以固定比率增加功能反应Ⅱ：捕食的增加率随食物密度增加而降低功能反应Ⅲ：捕食率随食物密度的增加而增加，随后因饱和而降低
Searching and handling
To obtain food,a predator must first search for its prey and then ‘handle’ (catch,process and eat) it,Diet width can be regarded as being determined by a balance between a generalist strategy of searching for a wide variety of prey (relatively easy) and a specialist strategy of searching for one type of prey and handling that very efficiently.
Optimal foraging theory assumes that evolution will have optimized predator behavior to maximize the rate of energy gain and makes predictions about how we should expect predators to balance searching and handling.
搜寻和处理为得到食物，捕食者必须首先搜寻猎物，然后处理（抓住、加工和吃掉猎物）。可以认为捕食者食谱的宽度是由泛化种对策与特化种对策之间的权衡决定的。泛化种对策捕食者寻找多种猎物（相对容易），特化种对策捕食者寻找一类猎物，非常有效的处理它。
最佳觅食理论假定进化会最优化动物行为以使其获得的能量效率最大，从而做出捕食者如何权衡搜寻与处理的预测。
最佳觅食理论计算能量效率的三个因素：猎物的能含量
搜寻时间
处理时间预言：（1）不会摄取无利可图的猎物
（2）搜寻强化 ----- 泛化种
（3）处理强化 ----- 特化种
（4）多产环境对特化种有利，非多产
环境对泛化种有利
Heterogeneity and prey refuges
Predator-prey experiments in the laboratory indicate that in simple environment,either (i) predators are able to consume all prey individuals,or (ii) the predator population becomes extinct and the prey survives,
If,however,the habitat is more complex some prey refuges and coexistence between predators and prey may occur,In corollary with the role of habitat patchiness in maintaining coexistence between competing species (see topic I1),environmental heterogeneity is likely to be of critical importance in allowing predators and prey to coexist.
异质性和猎物隐蔽处实验室捕食者—猎物实验表明在一个单纯环境中，或（i）捕食者吃掉所有猎物个体，或（ii）捕食者种群消亡而猎物存活。
然而，如果环境更为复杂，则一些猎物个体可能在猎物避难所中摆脱捕食，从而出现捕食者—猎物的共存。由于生境斑块在维持竞争种间共存中所起的作用（见I1）推论，环境异质性很可能在允许捕食与猎物共存中具有关键的重要意义。
The ideal free distribution
Predators do not solely respond to the distribution and density of prey – they may also respond to the distribution of competing predators,Predators will tend to aggregate in the most profitable patches,but predator crowding will reduce the patch profitability until it is better to move to another less crowded patch,The ideal free distribution theory suggests that predators should move among sites until profitability is equal.
理想自由分布捕食者并不单独对猎物的分布与密度做出反应——它们对与之竞争的捕食者的分布也会反应。捕食者趋向于聚集在最有利可图的斑块中，但捕食者之间的拥挤会降低斑块的有利度，直到移到另一块不太拥挤的斑块中去会更好。理想自由分布理论认为捕食者会在各分布区间移动，直到各区有利度相等。
Plant defense
Plants defend themselves from predation in two main ways,(i) toxicity and unpalatablity,There is a vast variety of chemical ammunition found in the plant kingdom used to defend plants against attacks from predators and parasites,These secondary compounds may either be directly toxic or they may reduce the food value of the plant,for example,by reducing the availability of the leaf tissue protein to the animal gut,
(ii) defensive structures,Defensive structures exist on a variety of scales,from small hairs on the leaf surface which may trap insects and other invertebrates,to large spines which deter mammalian herbivores,Both the levels of secondary compounds and the size of defensive structures may be elevated or ‘induced’ in plants that have suffered defoliation.
植物防御植物以两种主要方式来保护自己免遭捕食：（i）毒性与差的味道，和在植物王国已发现大量的多种化学武器来保卫植物免遭捕食和寄生者的进攻。这些次生性化合物或直接有毒，或可降低植物的食物价值，如降低动物肠道对植物叶组织蛋白的吸收。
（ii）防御结构。防御结构在各种水平上都存在，从叶表面可陷住昆虫及其他无脊椎动物的微小绒毛，到可阻止哺乳类草食动物的大型针刺。经历过落叶的植物，其次生化合物水平及防御结构大小都会提高或“被诱导”。
Intraspecific Competition
As individuals are quite similar in their resource requirements,such competition may be particularly intense,Intraspecific competition is a major force in ecology and is responsible for phenomena such as dispersal and territoriality,as well as being the primary cause of population regulation via density-dependent processes.
当个体对资源的需要非常相似时，竞争会特别强烈。种内竞争是生态学的一种主要影响力，是扩散和领域现象的原因，并且是种群通过密度制约过程进行调节的主要原因。
Density dependence
Density dependence describes the relationship between fitness and population size,A key population regulatory factor is negative density dependence,where declining fitness occurs as population density increases within a species due to intraspecific competition.
密度制约密度制约描述适合度与种群大小之间的关系。种群调节的一个关键因子是负的密度制约，当种群密度增加时，由于种内竞争，使适合度下降。
Self-thinning
Sessile organisms,including plants,cannot escape competition by movement,and therefore the losers in the competitive battle die,In a group of plants of the same age,this results in fewer individuals of larger size surviving,This process is described as ‘self-thinning’,Self-thinning results in a relationship between density and individual plant mass,which typically has a slope of –3/2on a log-log plot,This relationship is known as Yoda’s –3/2 law.
自 疏固着生长的生物，包括植物，不能通过运动逃避竞争，因此竞争中的失败者死去在同样年龄大小的植物群中，这种竞争结果使较少量的较大个体存活下来。这一过程叫做“自疏”。自疏导致密度与植物个体大小之间的关系，这在双对数作图时呈现典型的-3/2斜率。这种关系叫做Yoda-3/2自疏法则。
Dispersal
Organisms can respond to high levels of intraspecific competition by dispersing away from the area of high population.density,Even in species that are sessile for most of the lifecycle,there is a mobile dispersal stage,Dispersal is often undertaken by the younger members of a population,whilst in many mammal species males disperse more than females do
扩 散生物可通过扩散离开种群密度高的地区，来对高水平的种内竞争做出反应。即使在生活周期内大部分时间营固着生活的种类，也有一个可运动的扩散期。扩散通常由种群内较年轻的个体进行，而在许多哺乳动物中雄性比雌性扩散更多。
Territoriality
In many animal species (including insects,birds and mammals) individuals or groups compete for areas of space,There is active interference between individuals to maintain the territory boundaries,Territoriality gives a benefit to the territory-holder,such that the costs of defending the territory against intruders are outweighed by advantages such as increased food supplies,increased mating success and reduced predation risk.
领 域 性许多动物种（包括昆虫、鸟类和哺乳动物）的个体或群体为争夺空间而竞争。保持领域边界的个体间有积极的相互干扰行为。领域使其所有者受益，为对抗入侵者，保护领域所付出的代价，被增加的食物供应、提高的交配成功率和降低的被捕食的危险所带来的价值超过。
SOCIAL GROUPS COOPERATION AND ALTRUISM
Cooperation
In many animal species,individuals cooperate for their mutual benefit,This cooperation can be temporary e.g,(for hunting or offspring care),or permanent,lasting the individual (e.g,an ant colony,or a pair of mute swans).
合 作许多动物，个体间有互利合作。这种合作可以是暂时性的（如共同猎食、关怀后代），或者是长久性的，在一生中都保持着（如蚂蚁的群体，或一对缄默的天鹅）。
Eusocial society
A select group of animal species display an extreme form of sociality,in which there is a reproductive division of labor,some individuals (usually called ‘workers’) forego reproduction,whilst others are fertile (‘sexuals’ such as queens),This type of society is only common among a group of insects in the order Hymenoptera equipped with a sting – ants,bees and wasps.
真社会性的群体有一类动物种具有生殖分工，表现出极端的社会生活类型：一些个体放弃生殖（常常称为工蚁或工蜂），另一些则是能生殖的（有性的，如蚁后和蜂王）。此类社会群仅仅出现在具长刺的膜翅目昆虫，如蚂蚁、蜜蜂和胡蜂。
Grouping - benefits
Many species of animals form groups,such as flocks of starlings,shoals of herring or prides of lions,being in a group gives an animal some advantages,avoidance of predation,location of food and catching elusive or large prey.
集群——好处许多动物有集群，如椋鸟群、鲱鱼群、狮子群。集群给动物带来好处：逃避捕食动物（增加总的警觉程度；稀释效应；群防御）、找食物和捕捉受围困的或大个的猎物。
Grouping – costs
There are also costs of belonging to a group,increased competition for food,increased conspicuousness to predators,increased risk of disease.
集群——代价作为集群的一员也有弊处：增加竞争食物的强度、更易引起捕食者的注目、提高感染疾病的风险。
Altruism
Altruism occurs when an individual causes an increase in the fitness of another individual of the same species at a cost to its own survival or offspring production,An example is the sterile worker in a eusocial ant society,which sacrifices its opportunity of reproducing and instead supports its mother’s reproduction,This appears paradoxical,as it implies that the altruist is actively reducing its fitness,However,if the altruist is related to the beneficiary,this strategy may result in more of the altruist’s genes passing to the next generation.
利他行为利他行为出现在：当一个个体行为导致另一个适合度增加，同时以其牺牲自身存活或产后代为代价。例如真社会性的蚂蚁群体中不育的工蚁，它们牺牲自身生殖的机会，代之以对其母后生殖的支持。这意味着，利他主义者积极地减少其适合度。利他行为看起来似乎是矛盾的，然而，如果利他行为者与受惠者具有亲缘关系，这种对策可以使利他行为者有更多的基因遗传给下一代。
SEX IN ECOLOGY
Sex
Sex is a widespread phenomenon,found in plants and animals,which has a number of ecological consequences,Sex is evolutionarily important as it generates genetic variation,and ecologically important because the different sexes behave differently,The difference between sexes arises from the asymmetry in the energy invested in offspring development.
性性是植物和动物中广泛分布的现象，性有一系列生态后果。性在进化上的重要性是由于它产生遗传变异，它在生态学上的重要性则是因为不同性别的生物其行为不同。两性之间的区别是由于它们对后代发育的能量投资不对称性而产生的。
Sexual versus asexual reproduction
Sexual reproduction recombines the genomes of the parents producing genetically variable gametes and offspring,This maintenance of high levels of genetic variation enhances disease resistance and allows adaptation to unpredictable environmental conditions,In contrast,asexual reproduction does not generate genetic variation but can be seen as an adaptation to predictable environmental conditions.
有性和无性生殖有性生殖重组了来自双亲的基因组，产生遗传上变化的配子和后代。这种高水平遗传变异的维持增加了对疾病的抵抗力，允许有适应不可预测环境条件的能力。相反，无性生殖不产生遗传变异，但可以视为是对可预测环境条件的适应。
Sex ratio
The sex ratio is the ratio of males to females in a population,and usually is close to 1 male,1 female (Fisher’s sex ratio theory),However,unequal costs,crowding and mate competition can bias the sex ratio.
性 比性比是种群中雄体对雌体的比率，通常接近于1雄：1雌 (Fisher性比理论)。但是，不等的消耗、拥挤和配偶竞争也可能使性比偏离。
Sexual selection
Sexual selection causes such features as the peacock’s tail,the elaborate song of the male reed warbler and the antlers of the male stag,Sexual selection is caused by differences in reproductive success due to competition for mates.
性 选 择性选择导致形成像孔雀之尾、雄苇莺动听的歌唱、雄鹿的叉角等特征。交配竞争中生殖成效的不同导致性选择。
性选择理论
Darwin的理论
通过选择使某一性个体在寻求配偶时获得比同性其它个体更有竞争力的特征。
Fisher的理论
建立在主动选择基础上的性选择可以导致性二型特征的进化。
Trivers的理论
在雄性不承担任何抚育后代责任的物种中，如果雌性个体具有足够的辨别力，使它所选择的配偶所具有基因质量优于自身，那么，进行有性生殖仍然是有利的。
Mating systems
The social structure of mating in animals,and particularly in vertebrates,is an important ecological parameter,Monogamy is where one male and one female form a pair bond,either for a breeding season,or until one dies,Where one male mates with a number of females,polygyny occurs,whilst the opposite situation (which is rarer) where one female has a mating group of a number of males is known as polyandry.
交配体制动物，特别是脊椎动物，其交配的社会结构是重要的生态特征。一个雄体和一个雌体形成配偶，或者仅在繁殖季节，或者直到其中有一个死亡，这是单配制（monogyny）。当一个雄体与多个雌体交配，就出现了一雄多雌制（polygyny）；当出现相反情况（很少见），即一个雌体具有多个雄体的交配群，就叫做一雌多雄制（polyandry）。
交配体制反映了环境的生产力
The costs of inbreeding
When closely related individuals interbreed,‘inbreeding’ occurs,which gives rise to (i) inbreeding depression (which causes a reduction in offspring fitness) and (ii) increased genetic homozygosity (which reduces the possibility of evolutionary adaptation to a changing environment,and increases the possibility of extinction),Many species have mechanisms that prevent or curtail inbreeding.
近交的代价当亲缘相近的个体进行亲繁殖时，“交近”就出现了。近交引起（i）近交衰退（它使后代的适合度降低）和（ii）增加遗传纯合性（它降低了对于环境变化产生进化适应的可能性，而增加了灭绝的可能性）。许多物种具有防止或减少近交的机制。
Life History
Lire history
An organism’s life history is its lifetime pattern of growth and reproduction,
Life history includes,body size,growth rate,reproduction and longevity,
The observed in the life history patterns of different species is vast,
生活史
1、生物的生活史：一生中生长和繁殖的模式。
2、生活史的关键组分：个体大小、生长率、繁殖和寿命。3、不同种类其生活史类型的变异是巨大的。
Energy allocation and trade-offs
Darwinian demons：an organism to reach a large adult size shortly after birth,produce many large offspring and live to a great age,
能量分配和“权衡”
达尔文魔鬼,让某一生物在出生后短期内达到大型的成体大小，生产许多大个体后代并长寿。
Energy allocation and trade-offs
Energy allocated to one aspect of life history cannot be spent in another,so ‘trade-offs’ between different traits are inevitable.
Energy allocation,semelparity or iteroparitymany small offspring or less large offspring
能量分配和“权衡”
分配给生活史一方面的能量不能再用在另一方面，所以在不同生活史特性间进行“权衡”是不可避免的。
能量分配：单次生殖或多次生殖许多小型后代或较少较大型后代生活史对策生活史对策（life history strategy）：生物在进化过程中，对某些特定的生态压力(ecological pressure)所采取的生活史(life history)或行为(behavioral)策略。
繁殖对策（reproductive strategy）；取食对策（foraging strategy）；避敌对策（anti-predation strategy）；扩散对策(dispersal strategy) ………..
Reproductive values
The reproductive value (RVx) of an individual of age x,the number of offspring that individual is expected to produce in the immediate future + those expected over its remaining lifespan,
生 殖 价年龄x的个体的生殖价（RVx）:马上要生产的后代数量+预期的其在以后的生命过程中要生产的后代数量。
Reproductive values
The reproductive value of an individual inevitably rises after birth and falls towards old age,The difference in reproductive values between individuals provides a powerful predictor of life history strategy.
生 殖 价个体的生殖价在出生后必然会上升，然后随年龄老化而下降。个体间生殖价的差异提供了一个强有力的生活史对策预报器。
RVx = Mx+PRVx
PRVx = Σ(lx+i/lx)Mx+i
Mx,current mean reproductive value of age x (现时x年龄的个体平均繁殖力)
Mx+i,future mean reproductive value after age x (后续各年龄级个体平均繁殖力)
lx,current survivorship of age x (x年龄的个体生存率)
lx+i,future survivorship after age x (后续各年龄级个体生存率)
r- and K-selection
Two distinct life history strategies,r-selection theory
K-selection theory
r- selected species,maximize the rate of increase of the
population size
K-selected species,adapt to be competitive.
r -选择和K-选择两种明显的生活史对策,r-选择和K-选择理论
r-选择种类,种群增长率最大
K-选择种类,竞争性强。
r- and K-selection
r-selected species,rapid development,small adults,
many and small offspring and a short generation time,
K-selected species,slow development,large adult size,
few,large offspring and long generation times.
r -选择和K-选择
r-选择种类:发育快，成体小，后代数量多但体积小，世代时间短。
K-选择种类:发育慢，成体大，后代数量少但体积大，世代时间长。
r对策种群,生活在条件严酷和不可预测环境中的种群,其死亡率通常与种群密度无关,种群内个体常把较多的能量用于生殖,而把较少的能量用于生长、代谢和增强自身竞争能力.
K对策种群:生活在条件优越和可预测环境中的种
群,其死亡率通常由种群密度相关因素引起,生物间
存在激烈竞争,种群内个体常把更多的能量用于生
殖以外的其它各种活动.


讨 论为什么珍稀濒危动、植物为何要严加保护，否则将有灭绝的危险？
r-选择和K-选择的适应意义
r-选择：死亡率高，但r高能使种群迅速恢复，高扩散能力使其迅速离开不利环境，有利于建立新的种群和形成新的物种
K-选择：竞争能力强、数量稳定、大量死亡或导致生境退化的可能性小；由于r低，种群数量下降后恢复困难
r-K连续体（r-K continuum）:r-选择和K-选
择是两个进化方向的不同类型，从极端
的r-选择到极端的K-选择之间有许多过
类型，有的更接近于r-选择，有的更接
近于K-选择，两者间有一个连续的普系，
称r-K连续体
既是r-选择者又是K-选择者？
C- strategy,S- strategy and R- strategy
Grime’s ‘CSR triangle’ classifies habitats from a
perspective of plant life history,using the degree of
habitat disturbance (or stability) and its severity to
plants,
Grime的“CSR三角形”从植物生活史的观点，利用生境干扰（或稳定）程度及其对植物的严峻性来划分生境。
低严峻度，低干扰 --- 竞争对策（C-strategy）
低严峻度，高干扰 --- 杂草对策（R- strategy ）
高严峻度，低干扰 --- 胁迫-耐受对策（S- strategy ）
高严峻度，高干扰 --- 无法存活 （Uninhabitable）
Habitat classification
Habitats may be classified on the basis of the balance of benefits between growth and reproduction,into ‘high-cost-of-reproduction’ and ‘low-cost-of-reproduction’,
An alternative approach,‘bet-hedging’,considers the impact of the habitat on the relative variability of mortality or fecundity for different growth stages and uses this to predict optimal life history strategies,
生境分类生境可在生长与繁殖间利益平衡的基础上划分为“高繁殖付出”和“低繁殖付出”生境。
另一种可供选择的方法，“两面下注”考虑生境对不同生长期死亡率和繁殖力相关变化的影响，利用这种影响来预测最适生活史对策。
不同繁殖付出生境的物种
高-CR生境物种：推迟繁殖后代
低-CR生境物种：提前繁殖后代
,两面下注”理论
多次生殖：成体死亡率与幼体死亡率相比较
为稳定
单次生殖：幼体死亡率低于成体死亡率
Diapause
Diapause,Many organisms undergo a delay in
development at some stage in their life
cycle,such as seed diapause or implantation
delay in a red deer embryo.
滞育滞育,许多生物在生活史的某一阶段会推迟发育，如种子滞育和马鹿胚胎的植入推迟。
Dormancy
Dormancy,enter periods of reduced metabolic activity such as long-term hibernation or short- term torpor
This strategy is an adaptive response to avoid unfavorable conditions
休眠休眠：个体也可进入降低代谢活动的时期，如长时间的冬眠或短时间的蛰眠。
这种对策是为躲避不适宜环境的一种适应反应
Migration
Migration,directional movement,such as the autumn flight of swallows from Europe to Africa,
Dispersal,nondirectional movement away from the birth or breeding site,
迁 移迁徙,方向性运动，如燕子从欧洲到非洲的秋季飞行扩散,离开出生或繁殖地的非方向性运动。
There are three categories of migration,depending on whether an individual makes
(i) repeated return trips
(ii) a single return trip,
(iii) a one- way trip.
迁移有三种，依据生物个体做的是
（i）反复的往返旅行
（ii）单次往返旅行，
（iii）单程旅行。
Complex life cycles
Many plants,fungi and animals have complex life cycles,
individuals adopt radically different morpho
(1) logical forms (e.g,caterpillar / butterfly,tadpole / frog)
(2) generations differ radically from one another in a predictable fashion (e.g,haploid / diploid / alteration of generation in plants,sexual /asexual generations in rusts and aphids),
复杂的生活周期许多植物、真菌和动物具有复杂的生活周期在生活周期中，个体采用根本不同的形态学性状（如毛虫/蝴蝶，蝌蚪/青蛙）
(2) 世代以一种可预测的方式彼此根本不同（如植物的单倍体/双倍体世代交替，锈菌和蚜虫的有性/无性世代交替）。
Why are these complex strategies adopted?
trade-off between growth and dispersal
ptimization in habitat utilization
为什么要采用这些复杂的生活史对策呢？
扩散与生长的权衡
生境利用的最优化本 节 小 结生活史的相关概念
生物的能量分配与权衡
r-选择和K-选择
C-S-R对策
生物抵御不良环境的方式
滞育、休眠、迁徙等的概念
GENETIC VARIATION AND SPECIATION
Genes and alleles
Genes are pieces of DNA which contain the genetic code necessary to produce a specific protein,A gene can have many alleles and individuals can have a homozygous or heterozygous genotype,The phenotype expressed depends on whether alleles are dominant,recessive or codominant,The total set of genes and alleles present in a population is known as the gene pool,
基因和等位基因基因是带有可产生特定蛋白的遗传密码的DNA片段。一个基因可有许多等位基因，而个体可有纯合或杂合的基因型。表达的表现型取决于等位基因是显性的、隐性的还是共显性的。种群中存在的所有基因组和等位基因叫做基因库。
polymorphism
The term polymorphism refers to the presence of alleles in a population,A population or species may be polymorphic for color,as in snails,or for some biochemical function,as in plant toxicity,Some polymorphisms are maintained by natural selection,but others appear to result from the effect of many genes controlling the polymorphic character.
多 型多型指的是种群中等位基因的存在。一个种群或物种可能颜色是多型的，如蜗牛，或者一些生化特性是多型的，如植物的毒性。一些多型可能是由自然选择保持下来的，但其他是由于许多基因控制多型性状的结果。
物种进化进化动力：自然选择和遗传漂变
两种进化力作用,
中性说：认为遗传变异完全是突变和遗传漂变的结果，不包括自然选择。
筛选说：认为遗传变异是突变、遗传漂变和自然选择的联合结果。
平衡选择说：认为遗传变异完全是自然选择的结果。
稳定化选择:种群的所有表型按某种标准排列成一个序列,那么当自然选择有利于序列中位的表型并淘汰序列两端的表型.
定向选择:自然选择更有利于其中一端的表型,而不利于另一端.
分裂选择:自然选择可同时对序列两端的表型都有利,虽然有利的程度可能不同.
Genetic drift
Genetic drift is a random change in gene frequency arising through chance alone,It tends to be more apparent in small populations allele frequencies drift away from their starting values,increasing,decreasing or fluctuating up and down,It occurs because there is an element of chance in which individuals and which gametes will produce offspring and which individuals will die before reproducing,Random changes in allele frequency can lead to fixation and the progressive loss of genetic variation from the population,
遗传漂变遗传漂变是基因频率的随机变化，仅偶然出现。在小种群中，遗传漂变更明显。基因频率“漂离”起始值，增加、减少或上下波动。发生遗传漂变是因为在个体、产生后代的合子以及繁殖前死亡的个体中都有偶然要素。基因频率的随机变化导致来自种群的遗传变异的固定和逐渐丧失。
Genetic bottleneck
When a population undergoes an abrupt contraction in numbers,this is accompanied by a change in gene frequencies and a decline in the total genetic variation,Genetic drift in the small population during the bottleneck results in the loss of genetic variation,Although population numbers may recover,genetic variation will remain low for many generations.
遗传瓶颈当种群数量突然减少时，基因频率也会发生变化，总的遗传变异下降。瓶颈发生的时候，小种群的遗传漂变导致遗传变异丧失。尽管种群数量可以恢复，遗传变异在以后许多代仍会保持低水平。
SPECIATION
Reproductive species concept
The reproductive species concept focuses on the idea that species exist and maintain their genetic integrity and distinctness because they do not interbreed,The biological species concept and the recognition species concept both define species in terms of interbreeding,His view contrasts with the practical definition of species on the basis of distinguishing morphological characters.
繁殖种的概念繁殖种的概念，集中在如下思想：物种延续并保持其遗传的完整性和独特性是因为不进行异种杂交。生物种概念和识别种概念都根据相互杂交定义种。本观点与实际的物种定义不同的是后者以明显的形态学性状为基础。
Recognition species concept
The recognition concept views a species as a group of individuals with a common Specific Mate Recognition System (SMRS),The SMRS consists of all aspects of mating such as compatibility of reproductive organs and gametes,courtship song and behavior and pheromones,This species definition emphasizes the factors that keep species together,
识别种的概念识别种的概念定义种是一组具有共同的交配识别系统（SMRS）的个体。交配识别系统包括交配的所有方面，如繁殖器官和配子的兼容性、求偶鸣叫、行为和仪式。该种定义强调将种保持在一起的因素。
Biological species concept
This concept views species as a group of interbreeding natural populations that are reproductively isolated from other such groups,It allows populations that are indistinguishable morphologically to be classified as separate,sibling species because they do not interchange genes,Biological species are maintained by reproductive isolating mechanisms.
生物种的概念生物种概念认为种是一组可以相互杂交的自然种群，它们与其他种群间具有繁殖隔离。该概念将没有明显形态学差别的种群分成分离的姊妹种，因为它们不能彼此交换基因。生物种由繁殖隔离机制来保持。
物种形成的步骤地理物种形成学说认为：物种形成（allopatric speciation）过程大致分为三个步骤：
1、地理隔离；
2、独立进化；
3、生殖隔离机制的建立。


物种形成的方式异域性物种形成邻域性物种形成同域性物种形成
Allopatric speciation
Allopatric speciation occurs when the new species evolves in geographic isolation from the parent species,It may take place most readily in peripheral isolates,small populations at the extreme edge of a species range,The combined effect of a small atypical population and extreme environmental conditions can cause rapid and extensive genetic reorganization (a genetic revolution) leading to speciation.
异域性物种形成与原来种由于地理隔离而进化形成新种，为异域性物种形成。异域性物种形成最易发生在边缘隔离、处在种分布区的极端边缘的小种群。小的非典型种群与极端环境条件的混合作用可产生迅速而广泛的遗传重组（遗传革命），从而导致物种形成。
Parapatric speciation
This form of speciation occurs where the speciating populations are contiguous but subject to different environmental (e.g,climatic) conditions in different parts of the range,Intermediate hybrids are found,as in ring species,but the large distances involved prevent the two types from merging completely.
邻域性物种形成邻域性物种形成发生在分布区相邻，但分布区内不同地点环境（如气候）条件不同的种群。如在环形种中那样，可发现中间杂种，但包括的很大的距离使两种类型不能完全混合。
Sympatric speciation
Sympatric speciation may occur where there is no geographical separation between the speciating populations of habitat preference,Whether sympatric speciation happens at all is a contentious issue,although rapid changes in the host preference of phytophagous insects has been observed,Plants can undergo sympatric speciation through polyploidy.
同域性物种形成同域性物种形成可能发生在没有地理隔离，但具有宿主选择差异、食物选择差异或生境选择差异的种群。同域性物种形成是否发生尚有争议，尽管已观察到植食性昆虫宿主选择的快速变化。植物可以通过多倍体进行同域性物种形成。
THE COMMUNITY,STRUCTURE AND STABILITY
The community
The community is an assemblage of species populations that occur together in the same place at the same time,
群 落群落（community）是在相同时间聚集在同一地段上的许多物种种群（species populations）的集合。
群落的基本特征
1、具有一定的外貌
2、具有一定的种类组成
3、具有一定的群落结构
4、形成群落环境
5、不同物种之间的相互影响
6、一定的动态特征
7、一定的分布范围
8、群落的边界特征群落的性质机体论学派群落是一个和生物个体、种群相似的自然单位，是有生命的系统
群落演替的定向特征相当于生物的生活史或生物的发育，具有机体特征
群落都要经历从先锋阶段到顶级阶段的演替过程
顶级群落受破坏后重复演替过程达到顶级群落阶段个体论学派群落不是自然单位，而是自然界中在空间和时间连续变化系列中的一个区段
因为在连续变化的环境下的群落组成是逐渐变化的，群落间没有明显的边界
群落和物种的关系不是有集体和组织器官的关系
群落的发育过程是物种的更替和种群数量消长过程
和有机体不同，群落不可能在不同生境下保持繁殖的一致性
同一群落类型之间无遗传上的联系现代生态学对群落的认识群落存既在着连续性的一面，也有间断性的一面
如果采取生境梯度的分析的方法，即排序的方法来研究连续群落变化，在不少情况下，表明群落并不是分离的、有明显边界的实体，而是在空间和时间上连续的一个系列
如果排序的结果构成若干点集的话，则可达到群落分类的目的；如果分类允许重叠的话，则又可反映群落的连续性
群落的连续性和间断性之间并不一定要相互排斥，关键在于研究者看待问题的角度和尺度
Species diversity
The species diversity of a community depends on the number of different species it contains (the species richness) and the evenness of species abundance across species,Diversity indices can be calculated to take into account both of these factors,
物种多样性一个群落的物种多样性取决于群落含有的不同种的数量即种丰富度（the species richness）和种多度的均匀性（the evenness of species abundance）。多样性指数（diversity indices）可以通过这两个因子计算出来。
生物多样性生物多样性(biodiversity)的概念
生物种的多样化和变异性以及物种生境的生态复杂性
生物多样性的三个水平
遗传多样性：地球上生物个体中所包含的遗传信息的总和
物种多样性：地球上多种多样的生物类型及种类
生态系统多样性：是生物圈中生物群落、生境和生态过程的丰富程度
Diversity can be measured over the three different spatial scales of the local community,the region and the broadest geographic scale (e.g,the continent),This yields alpha (α)-,beta (β)-and gamma (γ)-diversity,
多样性能够在局域群落（local community）、地区（region）和最广阔的地理尺度（geographic scale）（如大陆）三个不同的空间尺度上测算它。这样就产生了a、β和Υ多样性。
物种多样性的测定
α多样性指数：栖息地或群中物种多样性
β多样性指数
沿着环境梯度的变化物种替代的程度
不同群落或某环境梯度上不同点之间的共有种越少，β多样性越大
精确地测定β多样性具有重要的意义
指示生境变化及其被物种分割的程度
用来比较不同地段的生境多样性
与α多样性一起构成了总体多样性或一定地段的生物异质性
( 多样性指数：一个地区或许多地区内穿过一系列群落
的物种多样性
α多样性指数
Simpson指数：D=1-ΣPi2
Shannon-Weiner指数 H =-ΣPilnPi
上二式中Pi种的个体数占群落中总个体数的比例，Pi=Ni/N。
Pielou均匀度指数：E=H/Hmax
Hmax为最大的物种多样性指数，Hmax=LnS
Simpson指数,
DA=0
DB=1-[(50/100)2+(50/100)2]=0.5000
Dc=1-ΣPi2=1-Σ(Ni/N)2=1-[(99/100)2+(1/100)2]=0.0198
Shannon-Wiener指数,
HA=0
HB=-(0.50×ln0.50+0.50×ln0.50)=0.69
HC=-ΣNi/N ln Ni/N= -(0.99×ln0.99+0.01×ln0.01)=0.056
Pielou均匀度指数,
Hmax=lnS=ln2=0.69
EA= H/Hmax=-[(1.0×ln1.0)+0]/0.69=0
EB=-(0.50×ln0.50+0.50×ln0.50)/0.69=0.69/0.69=1
EC=0.056/0.69=0.081
物种多样性的时空变化纬度：随纬度升高物种多样性降低
海拔：随海拔升高物种多样性降低
水体：随深度增加物种多样性降低
时间：
在群落演替的早期，随着演替的进展，物种多样性增加
在群落演替的后期，物种多样性会降低解释物种多样性变化的学说进化时间学说：热带群落比较古老，进化时间较长，并且在地质年代中环境条件稳定，很少遭受灾害性气候变化，所以群落的多样性较高。而温带和极地群落从地质年代比较年轻，遭受灾难性气候变化较多，所以多样性较低。
生态时间学说
：考虑时间尺度更短，认为物种的分布区的扩大也需要一定时间。
空间异质性学说：物理环境越复杂，或空间异质性越高，动植物群落的复杂性也越高，物种多样性也越大。如山区物种多样性明显高于平原；群落中小生境丰富多样，物种多样性越高。
气候稳定学说：气候越稳定，变化越小，动植物的种类越丰富，在生物进化的地质年代中，地球唯有热带的气候可能是最稳定的。
竞争学说：在环境严酷的地区，自然选择主要受物理因素控制，但在气候温和而稳定的热带地区，生物之间的竞争则成为进化和生态位分化的主要动力。
捕食学说：因为热带的捕食者比其他地区多，捕食者将被捕食者的种群数量压到较低水平，从而减轻了被食者的种间竞争。竞争的减弱允许更多的被食者种的生存。较丰富的种数又支持更多的捕食者种类。
生产力学说：如果其他条件相等，群落的生产力越高，生产的食物越多，通过食物网的能流量越大，物种多样性就越高。
群落的结构
群落的垂直结构群落的分层现象：与资源(光、矿质营养、食物等)利用有关
植物群落的成层现象地上成层现象、地下成层现象、层间植物
群落中动物的分层现象
主要与食物、微气候有关
水生群落的分层主要与光照、温度、食物和溶氧量有关
挺水草本层、飘浮草本层、水面高草层、沉水漂草层、沉水矮草层、水底层
漂浮动物、浮游动物、游泳动物、底栖动物、附底动物、底内动物群落的水平结构概念：群落的配置状况或水平格局
镶嵌性(mosaic)和小群落(microcoense)
环境异质性
影响群落水平结构的因素群落的时间结构概念：群落结构部分在时间上的相互更替，周期性变化
群落季相：群落优势生活型和层片结构的季节变化引起的群落外貌随季节的变化
时间格局：群落的组成与结构随时间序列发生有规律的变化
动物的季节性变化和动物的昼夜变化群落交错区与边缘效应群落交错区(生态交错区、生态过渡带,ecotone),
两个或多个群落之间(或生态地带之间)的过渡区域
边缘效应 (edge effect),
群落交错区种的数目及种的密度有增大的趋势
群落交错区的特点,
多种要素联合作用强烈，生物多样性较高
生态环境恢复原状的可能性较小
生态环境变化快，恢复困难
Ecotones
On the local and regional scale communities vary as the individual species respond to environmental gradients,The boundaries of individual species,communities and biomes are not distinct and abrupt,but blurred and gradual,Biomes merge into one another along ecotone,A vegetation map superimposes boundaries on this continuum,indicating approximately where one biome ends and another begins.
群落交错区在局域和地区范围内，当物种个体沿着环境梯度变化的时候，群落也发生了变化。物种、群落和生物群系的边界是不明显的和非突然断开的。而是模糊的和逐渐的。沿着生态交错区（ecotone），生物群系彼此融合。在这个连续体上植被图勾画出的边界指出了一个生物群系大概从哪结束，另一个从哪开始。
影响群落结构的因素
生物因素
竞争对生物群落结构的影响
捕食对生物群落结构的影响
干扰对生物群落结构的影响
岛屿与群落结构
Competition
Competition can be an important force shaping community structure,The ghost of competition past can leave a strong imprint on a community (e.g,as niche differentiation),Some studies of competition have shown that only one member of a guild of ecologically similar species tends to be present in the community,suggestive of competitive exclusion of other similar species,The distribution of supertramp bird species on islands also supports the theory that communities are structured by competition.
竞 争竞争可能是形成群落结构的一个重要力量过去竞争的痕迹在群落中可以留下很深的烙印（像生态位的分化）。竞争的一些研究已经表明，生态学上相似物种组成的同资源种团当中，仅仅只有一个成员在群落中能够生存，这就意味着其他相似物种被竞争排斥了。岛屿上超飘流的鸟类物种的分布也支持了该理论，即竞争导致了群落的结构化。
竞争：引起种间的生态位的分化，使群落中物种多样性增加
Keystone species
A keystone species has a significant and disproprtionate effect on the community,Keystone species can be top predators such as the northern sea otter; however,the term can be usefully applied to any species whose removal would have a significant effect on community structure.
关键物种关键（keystone）物种在群落中有一个重要的和不成比例的作用。关键种可能是顶端的捕食者，像北方的海獭；然而这个词可以运用在任何一个物种上，只要这个物种被移去时会对群落结构造成重大影响。
泛化种
捕食压力的加强，将有竞争能力的物种吃掉，使物种多样性增加
捕食压力过高时，因为需吃一些不适口的物种，物种多样性降低
特化种喜食的是群落的优势种，则捕食可以提高物种多样性
喜食的是竞争上占劣势的种类，则捕食会降低物种多样性
特化的捕食者，容易控制被食者物种
Grazers
Grazing animals have two effects on plant communities,(i) their selective feeding affects species abundance in the community,and (ii) grazing suppresses the growth of competitive species thus enhancing and maintaining the diversity of less competitive species,When grazing intensity is very high,diversity can be reduced as species are forced to local extinction.
食草动物食草动物对植物群落有两个作用：（i）它们选择摄食影响群落的物种多度。（ii）啃食抑制了竞争物种的生长，因此加速和维持了低竞争物种的多样性。当啃食强度很强时，物种多样性降低，物种会局部灭绝。
Carnivores
Selective predation and prey switching can leave rarer species unpredated,This behavior can lead to the coexistence of a large number of relatively rare species in the same community.
食肉动物选择捕食和转换猎物能够使稀有物种免遭捕杀。这种行为能够导致许多相对稀少的物种在同一个群落中共存。
Community complexity,diversity and stability
There are tow components to stability – resilience and resistance,which describe the community’s ability to recover from disturbance and to resist change,Complexity is thought to be important in determining resilience and resistance,
群落的复杂性、多样性和稳定性稳定性有两个组成成分——恢复力（resilience）和抵抗力（resistance）。这两个指标描述了群落在受到干扰后的恢复能力和抵御变化的能力。复杂性被认为是决定群落恢复力和抵抗力的重要因素。
In addition,different components of the communities (e.g,species richness and biomass) may respond differently to disturbance,Communities with a low productivity (e.g,tundra) to be the least resilient,In contrast,weak competition permits coexistence among species and reduces community instability.
此外，群落的不同组分（如种丰富度和生物量）也许对干扰有不同反应。具有较低生产力的群落（如冻原）其恢复力是最低的。相反，较弱的竞争可以使许多的物种共存，从而减少群落的不稳定性。
Stability also depends on environmental conditions – a fragile (complex or diverse) community may persist in a stable and predictable environment,while in a variable and unpredictable environment only simple and robust communities will survive.
稳定性也依赖于环境状况——一个脆弱的（复杂的或多样的）群落也许能够在一个稳定和可预知的环境中持续下去，而在一个多变的和不可预知的环境中，仅仅简单的和生长旺盛的群落才能够生存下去。
disturbance
A disturbance is an interruption or interference that occurs sufficiently often for it to have exerted some selection pressure on the species experiencing it,Disturbance includes trees falling in a forest,grazing by herbivores,tidal action,fire,unusual climatic conditions or human activity,Plants of environments prone to disturbance such as fire have morphological and life history adaptations to ensure the survival of themselves or their offspring.
干 扰干扰是指林中倒树、食草动物的啃食、潮汐活动、火灾、反常气候变化或人类活动等经常发生的扰乱或干涉，它们迫使物种经历某些选择压力。比如生长在易发生火灾的环境中的植物，在形态和生活史方面有其独特的适应，以保证它们自己和后代在这样的环境中生存下去。
Effects of disturbance on species richness
Disturbance can cause an increase in community species-richness by preventing dominance by a few competitive species and allowing opportunistic species to invade,Where populations are continually reduced by disturbance,competitive exclusion can be prevented and potentially competing species may be able to coexist.
干扰对物种丰富度的作用干扰可增加群落的物种多样性，因为它能阻止少数竞争力强的物种成为优势，使其他物种有机会入侵。如果某个地方的种群，由于干扰而不断减少，此地的竞争排斥就可能使那些本来相互竞争的物种停止竞争，而共存在一起。
The intermediate disturbance hypothesis
Maximum species diversity tends to be achieved when disturbance creates gaps for new species to colonize,but is not intense or frequent enough to community,At very low levels of disturbance the community is dominated by a few climax species,Very severe of repeated disturbance may have an impact on the physical or edaphic environment and alter the community completely,
中度干扰假说当干扰为新物种创造了可移殖的断层的时候，物种多样性趋向最大。但这种干扰强度和频率均低于物种移殖的速度，因而在更大的群落中不会导致物种数的下降。如果干扰小，群落会被一些顶级物种统治。如果干扰很强并经常发生，就会对物理或土壤环境造成影响，从而完全改变群落。
Patch dynamics
Localized disturbance of a community creates gaps which can then be colonized by individuals of the same or another species,Potentially,competing species may not encounter one another because of the stochastic nature of gap colonization,allowing species-rich communities to persist,In a late successional community such as a forest,gaps undergo a mini-succession resulting in a mosaic of patches at different stages of succession.
斑块动态群落的局部性干扰产生了许多断层，相同的或不同的物种个体就乘机移殖到这些断层上来。由于物种移殖到哪个断层是随机的，因此相互竞争的物种可能不会在同一断层上相遇。这样就会使物种丰富的群落生存下来。在晚期演替群落中，如森林群落，断层经历了一个微型演替（mini-succession）的过程，因此形成了一个由处于不同演替阶段的各类斑块组成的镶嵌体。
Founder-controlled communities
In some communities it seems that all species are equally good colonizers and are equally matched competitively,Here patch colonization is a matter of chance alone,This is the situation in some reef fish communities,Diversity is high because on one species is more likely to colonize than any other,A similar situation exists in chalk grassland communities England.
建设者控制群落在有些群落中，所有的物种似乎都移殖的不错，彼此在竞争上不分优劣。斑块移殖只是个别现象而已。有些珊瑚礁鱼群落就是如此，由于没有哪一个物种比任何其他物种更喜欢移殖，所以多样性高。在英国的Chalk草地群落中就存在着相似的情况。
ISLAND COMMUNITIES
The species-area relationship
The number of species on an island (or in any area) will increase with the size of the island,The increase is initially rapid,tailing off at the maximum number of species for a given habitat,A plot of log species number against log area gives a linear relationship,
物种-面积关系岛屿上（或一个地区中）物种数目会随着岛屿面积的增加而增加，最初增加十分迅速，当物种接近该生境所能承受的最大数量时，增加将逐渐停止。物种数目的对数与面积对数的坐标图显示的是一个线性关系。
For oceanic islands or islands of habitat,the slopes of these log-log plots mostly fall within the range 0.24-0.34,For subareas within continuous habitat,the slope is around 0.1,The effect of increasing species diversity with increasing area is more pronounced on islands than within continuous habitat.
对于海洋岛屿和生境岛屿来说，这些双对数坐标图直线的斜率，大多在0.24~0.34之间。对于连续生境内的亚区域，斜率接近0.1。随着面积增加，物种多样性增加的效果在岛屿上要比连续生境内明显。
Island biogeography
MacArthur and Wilson’s theory of island biogeography states that the number of species found on an island is determined by a dynamic equilibrium between the immigration of new colonizing species and the extinction of previously established ones,As the number of colonizing species increases,the number of immigrants arriving on the island decreases over time,In contrast,as competition among species becomes more intense,the extinction rate increases,The point at which extinction and colonization rates are equal gives the number of species at equilibrium,
岛屿生物地理学麦克阿瑟和威尔逊的岛屿生物地理学理论指出，岛屿上物种的数目是由新移殖来的物种和以前存在物种的灭绝之间的动态平衡决定的。当移殖种的数目增加时，到达岛屿的移殖来的物种的数目会随着时间的推移而减少。相反，当物种之间的竞争变得强烈时，灭绝的速率就会增加。当灭绝和移殖的速率达到相等时，物种的数目就处于平衡稳定状态。
the model also accounts for the increase in species number with increasing island size and decreasing distance from a source of colonists,Extinction and colonization account for the depauperate flora and fauna of islands when compared to the adjacent mainland.
模型研究也证明了物种的数目会随着岛屿面积的增加而增加，和随着距移殖者源距离的缩短而增加。对模型研究有利的证据，是由对除去动物的岛屿上物种的再移殖的观察，和对最近隔离的岛屿物种的丧失结果所提供的。当与邻近大陆对照的时候，灭绝和移殖过程说明了岛屿植物区系和动物区系的衰亡。
Islands and metapopulations
Metapopulation theory has superseded island biogeography in explaining the behavior of populations in ‘islands’ of fragmented habitat,A metapopulation consists of a number of populations that exchange individuals through immigration and emigration,Unlike islands,habitat patches are embedded in a landscape mosaic that can influence the quality of the patch and the species it will contain.
岛屿和异质种群异质种群理论已经替代了岛屿生物地理学来解释片断化生境的“岛屿”种群行为。异质种群含有许多种群，这些种群之间通过迁入和迁出而交换个体。与岛屿不同，生境斑块（patch）是在景观镶嵌板块（landscape mosaic）之中的，景观板块能够影响斑块的性质和它所含的物种种类。
岛屿生态与自然保护保护区面积
面积越大，能能支持和供养的物种越多
保护区的连片
所有小保护区物种相同时，的保护区能支持更多的物种
保护大型动物需较大面积的保护区
空间异质性丰富的区域，多个小保护区能保护更多的物种
多个小保护区有利于隔离传染病
保护区的廊道建设
保护区形状
细长的保护区有利于物种的交流和增加边缘生境
COMMUNITY DYNAMIC
Succession –the classical model
Ecological succession is defined as a continuous,unidirectional,sequential change in the species composition of a natural community,This sequence of community is termed a sere,and culminates in the climax community,
演替——经典模型生态演替是指在一个自然群落中，物种的组成连续地、单方向地、有顺序地变化。这一顺序被称为是一个演替序列，最后达到的阶段称为顶级。
Early successional stages are characterized by pioneer species,low biomass and often low nutrient levels,Community complexity increases as succession progresses,often peaking in the mid-successional stage,A mid-successional community is characterized by high biomass,high levels of organic nutrients and high species diversity.
早期的演替阶段，具有先锋物种、低生物量和低营养水平的特征。随着演替的进行，群落的复杂性增加，通常在演替的中期阶段，复杂性达到最大。一个中期的演替群落具有高生物量、高有机营养水平和高的物种多样性。
演替类型
Autogenic succession
Autogenic succession is self-driven,resulting from the interaction between organisms and their environment,Primary succession occurs on a newly formed substrate such as glacial till,Nutrient enhancement and litter accumulation by pioneer species allow new species to colonize,
自发演替自发演替的动力来自于生物与它们环境之间的相互作用。原生演替（primary succession）发生在新近形成的基质上，如冰川沉积物。先锋物种的营养物的增减和腐殖质的积累为新物种移殖做好了准备。
Secondary succession follows disturbance,for example by flooding,fire or human activity,In both types of autogenic succession pioneer species colonize quickly making opportunistic use of resources before the invasion of more competitive species,Shading leads to dominance by shade-tolerant species which tend to be slow colonizers.
次生演替是由于干扰引起的，如洪水、火灾和人类活动。在这两种自然发生的演替中先锋物种的移殖很快，在较强竞争力的物种入侵之前充分利用空间。耐阴物种（shade-tolerant species）成为阴影处的主宰者，它们是一些较慢的移殖者。
Degradative succession
Degradative succession is a type of autogenic succession involving colonization and subsequent decomposition of dead organic matter,Different species invade and disappear in turn,as the degradation of the organic matter uses up some resources and makes others available,This process leads to the production of humus and is important in soil formation.
退行性演替退行性演替是涉及到移殖和死亡有机体后来腐烂分解的自发演替的一种类型。当有机物质降解耗尽了一些资源和制造了其他可以利用的资源的时候，不同的物种就交替地出现和消失。这个过程导致了腐殖质的生产，并且对土壤形成过程起着重要作用。
Allogenic succession
Allogenic succession results from external environmental factors,such as long term climatic change (e.g,ice ages) or environmental change over a short time (e.g,sediment accretion),Changes in community structure over time are apparent from pollen analysis of sediment cores,Successional progress depends on species tolerance to environmental conditions such as salinity.
异发演替异发演替是由外界环境因素引起的，像长期的气候变化（如冰河时期）和环境在短时间内的变化（如沉积物的增加）。群落结构随时间的变化从沉积物芯样的花粉分析来看是十分明显的。演替依赖于物种对环境条件（如盐分）的忍耐性。
Successional processes
Succession is strongly influenced by three processes.
Facilitation,changes in the abiotic environment that are imposed by the developing community and allow other species to invade.
Inhibition,species of one stage resist invasion by later successional species such that invasion is only possible following disturbance or death.
（iii） Tolerance,late successional species invade because they are able to tolerate lower resource levels and can outcompete early successional species,Highly competitive species,which are tolerant of low resource levels will replace opportunistic good colonizers and come to dominate the climax community.
演替过程演替受三个过程的强烈影响：
（i）促进：正在发展的群落所产生的非生物环境变化，允许其他物种的入侵。
（ii）抑制：一个阶段的物种抵制后来演替的物种的入侵，以至于入侵仅仅在干扰或死亡后才有可能。
（iii）耐受：后期演替的物种的入侵，因为它仍能够忍受较低的资源水平和排斥早期演替的物种。能忍受低资源水平的强竞争的物种，将取代好的机会迁移者而统治顶极群。
控制演替的主要因素环境的不断变化植物繁殖体的迁移、散布和动物的活动性
种内、种间关系的改变
群落内部环境的变化
人类活动
Fluctuations and the climax community
There is no single climax community for a geographic area,but a continuum of climax types varying along environmental gradients,Climax communities are not stable,but are in a state of continual flux,Unidirectional succession to the climax does not always happen as succession can be arrested at an earlier stage,In general,biomass and species diversity increase with succession but often peak at an intermediate stage and not at the climax
波动和顶级群落作为一个地理区域，没有一个单一的顶极群落，但是都有一个连续的顶极类型系列沿着环境梯度变化着。顶极群落是不稳定的，但是它处于一个连续涨落之中。当演替在早期阶段被阻止的时候，朝向顶极的单向演替并不总是发生的。总之，生物量和物种多样性随着演替的进行而增加，但常常在演替中期阶段达到最大，而不是在顶极群落时。
THE COMMUNITY,STRUCTURE AND STABILITY
The community
The community is an assemblage of species populations that occur together in the same place at the same time,
群 落群落（community）是在相同时间聚集在同一地段上的许多物种种群（species populations）的集合。
群落的基本特征
1、具有一定的外貌
2、具有一定的种类组成
3、具有一定的群落结构
4、形成群落环境
5、不同物种之间的相互影响
6、一定的动态特征
7、一定的分布范围
8、群落的边界特征群落的性质机体论学派群落是一个和生物个体、种群相似的自然单位，是有生命的系统
群落演替的定向特征相当于生物的生活史或生物的发育，具有机体特征
群落都要经历从先锋阶段到顶级阶段的演替过程
顶级群落受破坏后重复演替过程达到顶级群落阶段个体论学派群落不是自然单位，而是自然界中在空间和时间连续变化系列中的一个区段
因为在连续变化的环境下的群落组成是逐渐变化的，群落间没有明显的边界
群落和物种的关系不是有集体和组织器官的关系
群落的发育过程是物种的更替和种群数量消长过程
和有机体不同，群落不可能在不同生境下保持繁殖的一致性
同一群落类型之间无遗传上的联系现代生态学对群落的认识群落存既在着连续性的一面，也有间断性的一面
如果采取生境梯度的分析的方法，即排序的方法来研究连续群落变化，在不少情况下，表明群落并不是分离的、有明显边界的实体，而是在空间和时间上连续的一个系列
如果排序的结果构成若干点集的话，则可达到群落分类的目的；如果分类允许重叠的话，则又可反映群落的连续性
群落的连续性和间断性之间并不一定要相互排斥，关键在于研究者看待问题的角度和尺度
Species diversity
The species diversity of a community depends on the number of different species it contains (the species richness) and the evenness of species abundance across species,Diversity indices can be calculated to take into account both of these factors,
物种多样性一个群落的物种多样性取决于群落含有的不同种的数量即种丰富度（the species richness）和种多度的均匀性（the evenness of species abundance）。多样性指数（diversity indices）可以通过这两个因子计算出来。
生物多样性生物多样性(biodiversity)的概念
生物种的多样化和变异性以及物种生境的生态复杂性
生物多样性的三个水平
遗传多样性：地球上生物个体中所包含的遗传信息的总和
物种多样性：地球上多种多样的生物类型及种类
生态系统多样性：是生物圈中生物群落、生境和生态过程的丰富程度
Diversity can be measured over the three different spatial scales of the local community,the region and the broadest geographic scale (e.g,the continent),This yields alpha (α)-,beta (β)-and gamma (γ)-diversity,
多样性能够在局域群落（local community）、地区（region）和最广阔的地理尺度（geographic scale）（如大陆）三个不同的空间尺度上测算它。这样就产生了a、β和Υ多样性。
物种多样性的测定
α多样性指数：栖息地或群中物种多样性
Simpson指数：D=1-ΣPi2
Shannon-Weiner指数 H =-ΣPilnPi
上二式中Pi种的个体数占群落中总个体数的比例，Pi=Ni/N。
Pielou均匀度指数：E=H/Hmax
Hmax为最大的物种多样性指数，Hmax=LnS
Simpson指数,
DA=0
DB=1-[(50/100)2+(50/100)2]=0.5000
Dc=1-ΣPi2=1-Σ(Ni/N)2=1-[(99/100)2+(1/100)2]=0.0198
Shannon-Wiener指数,
HA=0
HB=-(0.50×ln0.50+0.50×ln0.50)=0.69
HC=-ΣNi/N ln Ni/N= -(0.99×ln0.99+0.01×ln0.01)=0.056
Pielou均匀度指数,
Hmax=lnS=ln2=0.69
EA= H/Hmax=-[(1.0×ln1.0)+0]/0.69=0
EB=-(0.50×ln0.50+0.50×ln0.50)/0.69=0.69/0.69=1
EC=0.056/0.69=0.081
β多样性指数
沿着环境梯度的变化物种替代的程度
不同群落或某环境梯度上不同点之间的共有种越少，β多样性越大
精确地测定β多样性具有重要的意义
指示生境变化及其被物种分割的程度
用来比较不同地段的生境多样性
与α多样性一起构成了总体多样性或一定地段的生物异质性
( 多样性指数：一个地区或许多地区内穿过一系列群落
的物种多样性物种多样性的时空变化纬度：随纬度升高物种多样性降低
海拔：随海拔升高物种多样性降低
水体：随深度增加物种多样性降低
时间：
在群落演替的早期，随着演替的进展，物种多样性增加
在群落演替的后期，物种多样性会降低解释物种多样性变化的学说进化时间学说：热带群落比较古老，进化时间较长，并且在地质年代中环境条件稳定，很少遭受灾害性气候变化，所以群落的多样性较高。而温带和极地群落从地质年代比较年轻，遭受灾难性气候变化较多，所以多样性较低。
生态时间学说：考虑时间尺度更短，认为物种的分布区的扩大也需要一定时间。
空间异质性学说：物理环境越复杂，或空间异质性越高，动植物群落的复杂性也越高，物种多样性也越大。如山区物种多样性明显高于平原；群落中小生境丰富多样，物种多样性越高。
气候稳定学说：气候越稳定，变化越小，动植物的种类越丰富，在生物进化的地质年代中，地球唯有热带的气候可能是最稳定的。
竞争学说：在环境严酷的地区，自然选择主要受物理因素控制，但在气候温和而稳定的热带地区，生物之间的竞争则成为进化和生态位分化的主要动力。
捕食学说：因为热带的捕食者比其他地区多，捕食者将被捕食者的种群数量压到较低水平，从而减轻了被食者的种间竞争。竞争的减弱允许更多的被食者种的生存。较丰富的种数又支持更多的捕食者种类。
生产力学说：如果其他条件相等，群落的生产力越高，生产的食物越多，通过食物网的能流量越大，物种多样性就越高。
群落的结构
群落的垂直结构
群落的分层现象：与资源(光、矿质营养、食物等)利用有关
植物群落的成层现象地上成层现象、地下成层现象、层间植物
群落中动物的分层现象
主要与食物、微气候有关
水生群落的分层主要与光照、温度、食物和溶氧量有关
挺水草本层、飘浮草本层、水面高草层、沉水漂草层、沉水矮草层、水底层
漂浮动物、浮游动物、游泳动物、底栖动物、附底动物、底内动物群落的水平结构概念：群落的配置状况或水平格局
镶嵌性(mosaic)和小群落(microcoense)
环境异质性
影响群落水平结构的因素群落的时间结构概念：群落结构部分在时间上的相互更替，周期性变化
群落季相：群落优势生活型和层片结构的季节变化引起的群落外貌随季节的变化
时间格局：群落的组成与结构随时间序列发生有规律的变化
动物的季节性变化和动物的昼夜变化群落交错区与边缘效应群落交错区(生态交错区、生态过渡带,ecotone),
两个或多个群落之间(或生态地带之间)的过渡区域
边缘效应 (edge effect),
群落交错区种的数目及种的密度有增大的趋势
群落交错区的特点,
多种要素联合作用强烈，生物多样性较高
生态环境恢复原状的可能性较小
生态环境变化快，恢复困难
Ecotones
On the local and regional scale communities vary as the individual species respond to environmental gradients,The boundaries of individual species,communities and biomes are not distinct and abrupt,but blurred and gradual,Biomes merge into one another along ecotone,A vegetation map superimposes boundaries on this continuum,indicating approximately where one biome ends and another begins.
群落交错区在局域和地区范围内，当物种个体沿着环境梯度变化的时候，群落也发生了变化。物种、群落和生物群系的边界是不明显的和非突然断开的。而是模糊的和逐渐的。沿着生态交错区（ecotone），生物群系彼此融合。在这个连续体上植被图勾画出的边界指出了一个生物群系大概从哪结束，另一个从哪开始。
影响群落结构的因素生物因素
竞争对生物群落结构的影响
捕食对生物群落结构的影响
干扰对生物群落结构的影响
岛屿与群落结构
Competition
Competition can be an important force shaping community structure,The ghost of competition past can leave a strong imprint on a community (e.g,as niche differentiation),Some studies of competition have shown that only one member of a guild of ecologically similar species tends to be present in the community,suggestive of competitive exclusion of other similar species,The distribution of supertramp bird species on islands also supports the theory that communities are structured by competition.
竞 争竞争可能是形成群落结构的一个重要力量过去竞争的痕迹在群落中可以留下很深的烙印（像生态位的分化）。竞争的一些研究已经表明，生态学上相似物种组成的同资源种团当中，仅仅只有一个成员在群落中能够生存，这就意味着其他相似物种被竞争排斥了。岛屿上超飘流的鸟类物种的分布也支持了该理论，即竞争导致了群落的结构化。
竞争：引起种间的生态位的分化，使群落中物种多样性增加
Keystone species
A keystone species has a significant and disproprtionate effect on the community,Keystone species can be top predators such as the northern sea otter; however,the term can be usefully applied to any species whose removal would have a significant effect on community structure.
关键物种关键（keystone）物种在群落中有一个重要的和不成比例的作用。关键种可能是顶端的捕食者，像北方的海獭；然而这个词可以运用在任何一个物种上，只要这个物种被移去时会对群落结构造成重大影响。
泛化种
捕食压力的加强，将有竞争能力的物种吃掉，使物种多样性增加
捕食压力过高时，因为需吃一些不适口的物种，物种多样性降低
特化种喜食的是群落的优势种，则捕食可以提高物种多样性
喜食的是竞争上占劣势的种类，则捕食会降低物种多样性
特化的捕食者，容易控制被食者物种
Grazers
Grazing animals have two effects on plant communities,(i) their selective feeding affects species abundance in the community,and (ii) grazing suppresses the growth of competitive species thus enhancing and maintaining the diversity of less competitive species,When grazing intensity is very high,diversity can be reduced as species are forced to local extinction.
食草动物食草动物对植物群落有两个作用：（i）它们选择摄食影响群落的物种多度。（ii）啃食抑制了竞争物种的生长，因此加速和维持了低竞争物种的多样性。当啃食强度很强时，物种多样性降低，物种会局部灭绝。
Carnivores
Selective predation and prey switching can leave rarer species unpredated,This behavior can lead to the coexistence of a large number of relatively rare species in the same community.
食肉动物选择捕食和转换猎物能够使稀有物种免遭捕杀。这种行为能够导致许多相对稀少的物种在同一个群落中共存。
Community complexity,diversity and stability
There are tow components to stability – resilience and resistance,which describe the community’s ability to recover from disturbance and to resist change,Complexity is thought to be important in determining resilience and resistance,In addition,different components of the communities (e.g,species richness and biomass) may respond differently to disturbance,Communities with a low productivity (e.g,tundra) to be the least resilient,In contrast,weak competition permits coexistence among species and reduces community instability.Stability also depends on environmental conditions – a fragile (complex or diverse) community may persist in a stable and predictable environment,while in a variable and unpredictable environment only simple and robust communities will survive.
群落的复杂性、多样性和稳定性稳定性有两个组成成分——恢复力（resilience）和抵抗力（resistance）。这两个指标描述了群落在受到干扰后的恢复能力和抵御变化的能力。复杂性被认为是决定群落恢复力和抵抗力的重要因素。此外，群落的不同组分（如种丰富度和生物量）也许对干扰有不同反应。具有较低生产力的群落（如冻原）其恢复力是最低的。相反，较弱的竞争可以使许多的物种共存，从而减少群落的不稳定性.稳定性也依赖于环境状况——一个脆弱的（复杂的或多样的）群落也许能够在一个稳定和可预知的环境中持续下去，而在一个多变的和不可预知的环境中，仅仅简单的和生长旺盛的群落才能够生存下去。
disturbance
A disturbance is an interruption or interference that occurs sufficiently often for it to have exerted some selection pressure on the species experiencing it,Disturbance includes trees falling in a forest,grazing by herbivores,tidal action,fire,unusual climatic conditions or human activity,Plants of environments prone to disturbance such as fire have morphological and life history adaptations to ensure the survival of themselves or their offspring.
干 扰干扰是指林中倒树、食草动物的啃食、潮汐活动、火灾、反常气候变化或人类活动等经常发生的扰乱或干涉，它们迫使物种经历某些选择压力。比如生长在易发生火灾的环境中的植物，在形态和生活史方面有其独特的适应，以保证它们自己和后代在这样的环境中生存下去。
Effects of disturbance on species richness
Disturbance can cause an increase in community species-richness by preventing dominance by a few competitive species and allowing opportunistic species to invade,Where populations are continually reduced by disturbance,competitive exclusion can be prevented and potentially competing species may be able to coexist.
干扰对物种丰富度的作用干扰可增加群落的物种多样性，因为它能阻止少数竞争力强的物种成为优势，使其他物种有机会入侵。如果某个地方的种群，由于干扰而不断减少，此地的竞争排斥就可能使那些本来相互竞争的物种停止竞争，而共存在一起。
The intermediate disturbance hypothesis
Maximum species diversity tends to be achieved when disturbance creates gaps for new species to colonize,but is not intense or frequent enough to community,At very low levels of disturbance the community is dominated by a few climax species,Very severe of repeated disturbance may have an impact on the physical or edaphic environment and alter the community completely,
中度干扰假说当干扰为新物种创造了可移殖的断层的时候，物种多样性趋向最大。但这种干扰强度和频率均低于物种移殖的速度，因而在更大的群落中不会导致物种数的下降。如果干扰小，群落会被一些顶级物种统治。如果干扰很强并经常发生，就会对物理或土壤环境造成影响，从而完全改变群落。
Patch dynamics
Localized disturbance of a community creates gaps which can then be colonized by individuals of the same or another species,Potentially,competing species may not encounter one another because of the stochastic nature of gap colonization,allowing species-rich communities to persist,In a late successional community such as a forest,gaps undergo a mini-succession resulting in a mosaic of patches at different stages of succession.
斑块动态群落的局部性干扰产生了许多断层，相同的或不同的物种个体就乘机移殖到这些断层上来。由于物种移殖到哪个断层是随机的，因此相互竞争的物种可能不会在同一断层上相遇。这样就会使物种丰富的群落生存下来。在晚期演替群落中，如森林群落，断层经历了一个微型演替（mini-succession）的过程，因此形成了一个由处于不同演替阶段的各类斑块组成的镶嵌体。
Founder-controlled communities
In some communities it seems that all species are equally good colonizers and are equally matched competitively,Here patch colonization is a matter of chance alone,This is the situation in some reef fish communities,Diversity is high because on one species is more likely to colonize than any other,A similar situation exists in chalk grassland communities England.
建设者控制群落在有些群落中，所有的物种似乎都移殖的不错，彼此在竞争上不分优劣。斑块移殖只是个别现象而已。有些珊瑚礁鱼群落就是如此，由于没有哪一个物种比任何其他物种更喜欢移殖，所以多样性高。在英国的Chalk草地群落中就存在着相似的情况。
ISLAND COMMUNITIES
The species-area relationship
The number of species on an island (or in any area) will increase with the size of the island,The increase is initially rapid,tailing off at the maximum number of species for a given habitat,A plot of log species number against log area gives a linear relationship,
For oceanic islands or islands of habitat,the slopes of these log-log plots mostly fall within the range 0.24-0.34,For subareas within continuous habitat,the slope is around 0.1,The effect of increasing species diversity with increasing area is more pronounced on islands than within continuous habitat.
物种-面积关系岛屿上（或一个地区中）物种数目会随着岛屿面积的增加而增加，最初增加十分迅速，当物种接近该生境所能承受的最大数量时，增加将逐渐停止。物种数目的对数与面积对数的坐标图显示的是一个线性关系。
对于海洋岛屿和生境岛屿来说，这些双对数坐标图直线的斜率，大多在0.24~0.34之间。对于连续生境内的亚区域，斜率接近0.1。随着面积增加，物种多样性增加的效果在岛屿上要比连续生境内明显。
Island biogeography
MacArthur and Wilson’s theory of island biogeography states that the number of species found on an island is determined by a dynamic equilibrium between the immigration of new colonizing species and the extinction of previously established ones,As the number of colonizing species increases,the number of immigrants arriving on the island decreases over time,In contrast,as competition among species becomes more intense,the extinction rate increases,The point at which extinction and colonization rates are equal gives the number of species at equilibrium,
the model also accounts for the increase in species number with increasing island size and decreasing distance from a source of colonists,Extinction and colonization account for the depauperate flora and fauna of islands when compared to the adjacent mainland.
岛屿生物地理学麦克阿瑟和威尔逊的岛屿生物地理学理论指出，岛屿上物种的数目是由新移殖来的物种和以前存在物种的灭绝之间的动态平衡决定的。当移殖种的数目增加时，到达岛屿的移殖来的物种的数目会随着时间的推移而减少。相反，当物种之间的竞争变得强烈时，灭绝的速率就会增加。当灭绝和移殖的速率达到相等时，物种的数目就处于平衡稳定状态。
模型研究也证明了物种的数目会随着岛屿面积的增加而增加，和随着距移殖者源距离的缩短而增加。对模型研究有利的证据，是由对除去动物的岛屿上物种的再移殖的观察，和对最近隔离的岛屿物种的丧失结果所提供的。当与邻近大陆对照的时候，灭绝和移殖过程说明了岛屿植物区系和动物区系的衰亡。
Islands and metapopulations
Metapopulation theory has superseded island biogeography in explaining the behavior of populations in ‘islands’ of fragmented habitat,A metapopulation consists of a number of populations that exchange individuals through immigration and emigration,Unlike islands,habitat patches are embedded in a landscape mosaic that can influence the quality of the patch and the species it will contain.
岛屿和异质种群异质种群理论已经替代了岛屿生物地理学来解释片断化生境的“岛屿”种群行为。异质种群含有许多种群，这些种群之间通过迁入和迁出而交换个体。与岛屿不同，生境斑块（patch）是在景观镶嵌板块（landscape mosaic）之中的，景观板块能够影响斑块的性质和它所含的物种种类。
岛屿生态与自然保护保护区面积
面积越大，能能支持和供养的物种越多
保护区的连片
所有小保护区物种相同时，的保护区能支持更多的物种
保护大型动物需较大面积的保护区
空间异质性丰富的区域，多个小保护区能保护更多的物种
多个小保护区有利于隔离传染病
保护区的廊道建设
保护区形状
细长的保护区有利于物种的交流和增加边缘生境
COMMUNITY DYNAMIC
Succession –the classical model
Ecological succession is defined as a continuous,unidirectional,sequential change in the species composition of a natural community,This sequence of community is termed a sere,and culminates in the climax community,
Early successional stages are characterized by pioneer species,low biomass and often low nutrient levels,Community complexity increases as succession progresses,often peaking in the mid-successional stage,A mid-successional community is characterized by high biomass,high levels of organic nutrients and high species diversity.
演替——经典模型生态演替是指在一个自然群落中，物种的组成连续地、单方向地、有顺序地变化。这一顺序被称为是一个演替序列，最后达到的阶段称为顶级。
早期的演替阶段，具有先锋物种、低生物量和低营养水平的特征。随着演替的进行，群落的复杂性增加，通常在演替的中期阶段，复杂性达到最大。一个中期的演替群落具有高生物量、高有机营养水平和高的物种多样性。
演替类型
Autogenic succession
Autogenic succession is self-driven,resulting from the interaction between organisms and their environment,Primary succession occurs on a newly formed substrate such as glacial till,Nutrient enhancement and litter accumulation by pioneer species allow new species to colonize,
自发演替自发演替的动力来自于生物与它们环境之间的相互作用。原生演替（primary succession）发生在新近形成的基质上，如冰川沉积物。先锋物种的营养物的增减和腐殖质的积累为新物种移殖做好了准备。
Secondary succession follows disturbance,for example by flooding,fire or human activity,In both types of autogenic succession pioneer species colonize quickly making opportunistic use of resources before the invasion of more competitive species,Shading leads to dominance by shade-tolerant species which tend to be slow colonizers.
次生演替是由于干扰引起的，如洪水、火灾和人类活动。在这两种自然发生的演替中先锋物种的移殖很快，在较强竞争力的物种入侵之前充分利用空间。耐阴物种（shade-tolerant species）成为阴影处的主宰者，它们是一些较慢的移殖者。
Degradative succession
Degradative succession is a type of autogenic succession involving colonization and subsequent decomposition of dead organic matter,Different species invade and disappear in turn,as the degradation of the organic matter uses up some resources and makes others available,This process leads to the production of humus and is important in soil formation.
退行性演替退行性演替是涉及到移殖和死亡有机体后来腐烂分解的自发演替的一种类型。当有机物质降解耗尽了一些资源和制造了其他可以利用的资源的时候，不同的物种就交替地出现和消失。这个过程导致了腐殖质的生产，并且对土壤形成过程起着重要作用。
Allogenic succession
Allogenic succession results from external environmental factors,such as long term climatic change (e.g,ice ages) or environmental change over a short time (e.g,sediment accretion),Changes in community structure over time are apparent from pollen analysis of sediment cores,Successional progress depends on species tolerance to environmental conditions such as salinity.
异发演替异发演替是由外界环境因素引起的，像长期的气候变化（如冰河时期）和环境在短时间内的变化（如沉积物的增加）。群落结构随时间的变化从沉积物芯样的花粉分析来看是十分明显的。演替依赖于物种对环境条件（如盐分）的忍耐性。
Successional processes
Succession is strongly influenced by three processes.
Facilitation,changes in the abiotic environment that are imposed by the developing community and allow other species to invade.
Inhibition,species of one stage resist invasion by later successional species such that invasion is only possible following disturbance or death.
（iii） Tolerance,late successional species invade because they are able to tolerate lower resource levels and can outcompete early successional species,Highly competitive species,which are tolerant of low resource levels will replace opportunistic good colonizers and come to dominate the climax community.
演替过程演替受三个过程的强烈影响：
（i）促进：正在发展的群落所产生的非生物环境变化，允许其他物种的入侵。
（ii）抑制：一个阶段的物种抵制后来演替的物种的入侵，以至于入侵仅仅在干扰或死亡后才有可能。
（iii）耐受：后期演替的物种的入侵，因为它仍能够忍受较低的资源水平和排斥早期演替的物种。能忍受低资源水平的强竞争的物种，将取代好的机会迁移者而统治顶极群。
控制演替的主要因素环境的不断变化植物繁殖体的迁移、散布和动物的活动性
种内、种间关系的改变
群落内部环境的变化
人类活动
Fluctuations and the climax community
There is no single climax community for a geographic area,but a continuum of climax types varying along environmental gradients,Climax communities are not stable,but are in a state of continual flux,Unidirectional succession to the climax does not always happen as succession can be arrested at an earlier stage,In general,biomass and species diversity increase with succession but often peak at an intermediate stage and not at the climax
波动和顶级群落作为一个地理区域，没有一个单一的顶极群落，但是都有一个连续的顶极类型系列沿着环境梯度变化着。顶极群落是不稳定的，但是它处于一个连续涨落之中。当演替在早期阶段被阻止的时候，朝向顶极的单向演替并不总是发生的。总之，生物量和物种多样性随着演替的进行而增加，但常常在演替中期阶段达到最大，而不是在顶极群落时。