种群和种群结构.pptx

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1、 H1 POPULATIONS AND POPULATION STRUCTURE A population is a group of organisms of the same species which occupies a given area.The boundaries between populations can be arbitrary.Populations may be categorized as consisting of either unitary or modular organisms.In unitary populations,each zygote giv

2、es 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 may then fragment producing many individual ramets.Key NotesPopulation第1页/共35页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

3、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。第2页/共35页种群密度一般种群密度很高第3页/共35页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 t

4、he number of pieces(ramets)or the number of shoots(modules)may give a more meaningful indication of abundance than the number of different individuals.Population size第4页/共35页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。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（

5、“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。相关主题出生率、死亡率和种群增长（H2）竞争的性质（I1）密度和密度制约（H3）捕食的性质（J1）种群动态波动、周期和混沌（H4）第5页/共35页第6页/共35页The age structure of a population is the number of individuals in each age class expressed as a ratio,and is usually displayed nor contracting nor contracting will have

6、 a stationary age distribution.A growing population will have more young.While a declining population will be dominated by older age classes.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

7、 description of the population.In species where growth rates are indeterminant(such ax plants),size classes may be more informative.Related topicsNatality,mortality and population The nature of competition(I1)growth (H2)The nature of predation (J1)Density and density dependence (H3)Population dynami

8、cs fluctuations,cycles and chaos (H4)Age and stage structure第7页/共35页H2 出生率、死亡率和种群增长出生率、死亡率和种群增长 要 点出 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。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。第8页/共35页H2 NATALITY,MORTALI

9、TY AND POPULATION GROWTH Nntality 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.Key NotesNatality The death r

10、ate,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 pr

11、obability of dying is the number dying per individual present at the start of the time period.mortality第9页/共35页存 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。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）。生 命 表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

12、同生群，这样的调查称为同生群分析。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。第10页/共35页人生三无奈第11页/共35页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

13、 a logarithmic scale through each phase of life.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).SurvivorshipLife tables summarize the f

14、ate 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.Life tables show the number of individuals present at different life stages or ages together with age-s

15、pecific 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 Life tables 第12页/共35页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

16、段是种群丧失率和种群大小波动的关键。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。第13页/共35页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

17、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-Factor analysisFecundity is the number of eggs,seeds,or offspring in the first stage of the life cycle produced by an ind

18、ividual.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.

19、The fecundity schedule第14页/共35页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。第15页/共35页The changes in population size over time can be calculated by addi

20、ng 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 =N +B+I D E For a particular set of conditions,an individual has a maxi

21、mum 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.population growth 第16页/共35页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

22、=rN第17页/共35页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 Intrinsic rate of increase Size at time t =population size dN/dt=rNDensity-independent population growth第1

23、8页/共35页密度制约性 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，这个最大数量称为环境容纳量（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。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

24、的那样。相关主题种群和种群结构（H1）竞争的性质（I1）密度和密度制约（H3）捕食的性质（J1）种群动态波动、周期和混沌（H4）第19页/共35页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 fas

25、t 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 dec

26、lines to zero as the population becomes more crowded and the population size stabilizes.This can be described as the logistic equation:Rate of change of Intrinsic rate Population Density dependentPopulation size at time t =of increase size factorDn/dt=rN(1-N/K)Where the density-dependent factor,(1-N

27、/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.Related topicsPopulations and population structure(H1)The natur

28、e of competition(I1)Density and density dependence(H3)Population dynamics-fluctuations,cycles and chaos(H4)Density-dependent growth-the logistic equtation第20页/共35页H3 密度和密度制约密度和密度制约 要 点密 度密度为单位面积、单位体积或单位生境中，个体的数量，对于一些植物和大型的或显眼的动物，可以计数它们的总的数量，对于许多在一定地区只能获得一部分样品的动物，其密度就必须进行估计。第21页/共35页人口密度分布图 第22页/共35页

29、H3 DENSITY AND DENSITY DEPENDENCEDensity is defined as the number of individuals per unit area,per volume or per unit of habitat.Total counts may be obtained for some plants and large or conspicuous animals.For many animals only a proportion of the individuals present in a given area will be detecte

30、d and density must be estimated.Key NotesDensity 第23页/共35页密度制约如果种群参数如出生率和死亡率随着种群密度的变化而变化，就可以说是密度制约的。如果出生率和死亡率不随着密度的变化而变化，则是非密度制约性的。如果没有迁移，除非出生率和死亡率是密度制约性的，否则种群会持续增长。估计密度：标志重捕法估计绝对密度可以使用以下方法：捕捉、标记捕捉个体、释放和再次捕捉。如果是随机捕捉，在第二次捕捉到的个体中，标记与没有标记个体的比例同整个种群中标记与没有标记个体的比例应当相等。因为已标记的总的个体数目是已知的，因此可根据以下公式来预测种群的总数量：捕

31、捉到的个体数/重捕个体数原来标记个体数 =种群总的个体数第24页/共35页Estimates of absolute density can be made with this method which involves trapping,marking trapped individuals,releasing them and trapping a second time.The proportion of marked to unmarked individuals in the traps will be the same as the proportion of marked to

32、unmarked in the whole population,assuming a random proportion of the population is trapped.Since the total number of marked animals is known an estimate of the total population can be obtained from the following equation:Number trappedNumber recaptured Number originally marked =Total number in popul

33、ationEstimation density-mark release recapturePopulation parameters such as birth and death rates which vary with density are said to be density dependent.Birth and death rates that do not change with density are density independent.In the absence of immigration,a population will continue to increas

34、e in number unless either the per capita birth rate or death rate is density dependent.Density dependence第25页/共35页补偿和密度制约密度制约有三种形式：过度补偿，补偿不足和准确补偿。如果密度制约引起的数量下降，没有超过或等于开始增加的个体数量，则密度制约是补偿不足。当密度制约的效应超过了开始种群数量的增加，称为过度补偿。如果下降个体数与开始增加的个体数相等，则称密度制约为准确补偿。相关主题种群和种群结构（H1）种群动态波动、周期和混沌（H4）捕食的性质（J1）竞争的性质（I1）出生率、

35、死亡率和种群增长（H2）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。第26页/共35页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 densi

36、ty is equivalent to the carrying capacity K.Related topicsPopulations and population structure Population dynamics-fluctuations,(H1)cycles and chaos(H4)Natality,mortality and population The mature of competition (I1)growth (H2)The mature of predation (J1)Equilibrium population densityCompensation an

37、d density dependenceThere are three types of density dependence:overcompensating,under compensating and exactly compensating.If a decline in numbers due to density dependence does not outweigh or balance the initial increase in numbers,density dependence is under compensating.Overcompensating densit

38、y dependence occurs where the effect of increased density more than outweighs the initial augmentation.If the decline in numbers exactly balances the initial increase in density,density dependence is said to be exactly compensating.第27页/共35页H4 种群动态种群动态波动、周期和混沌波动、周期和混沌 要 点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

39、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。第28页/共35页种群密度周期性变化迁徙耕种第29页/共35页H4 POPULATION DYNAMICS FLUCTUATIONS,CYCLES AND CHAOSMost 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 change

40、s in environmental conditions or because of changes to their biotic environment.Key NotesExpanding and coutracting populations第30页/共35页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

41、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。第31页/共35页Populations fluctuationsPopulations may fluctuate for a number of reasons:(i)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 sh

42、ow 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

43、 not damp down)or chaotic fluctuations that appear random;(iii)Environmental stochasticity.This is a nondeterministic,unpredictable variation in the environmental conditions,resulting in a changing equilibrium density.第32页/共35页相关主题出生率、死亡率和种群增长（H2）捕食行为猎物反应（J2）密度和密度制约（H3）混 沌数学上有关混沌的定义与俗语中的用法是截然不同的。一个混

44、沌系统是受确定性作用控制的，而不是随机的。混沌的结果依赖于初始状态的精确值。由于完全精确是不可能达到的，因此对混沌系统不能进行有效的预测。目前，对于观察到的有关种群大小波动在何种程度上是受混沌过程影响的还不清楚。一些分析认为，麻疹的爆发和一些昆虫种群可能表现出混沌的动态变化。第33页/共35页Related topicsNatality,mortality and population Predator behavior and prey growth (H2)response (J2)Density and density dependence (H3)ChaosThe mathematic

45、al definition of chaos is quite distinct from the colloquial use of this term.A chaotic system is driven by a deterministic process,it is not conditions.As perfect accuracy is impossible to attain,chaotic systems are effectively unpredictable.It is currently unclear to what extent observed fluctuations in population sizes are influenced by chaotic processes.Some analyses suggest that measles outbreaks and some insect populations may display chaotic dynamics.第34页/共35页感谢您的观看！第35页/共35页