Population Ecology2.ppt

1、第四节 inter-specific interaction,Definition: interaction of different species 关系类型 关系特点 competition(- -) 彼此互相抑制 predation (+ -) 种群A杀死或吃掉种群B一些个体 parasitism(+ -) 种群A寄生于种群B,并有害于后者 Neutralism(0 0) 彼此互不影响 symbiosis(+ +) 彼此互相有利,专性 Mutualism(+ +) 彼此互相有利,兼性 commensalism (+ 0) 对A种群有利,对种群B无利害 amensalism (- 0) 对

2、A种群有害,对种群B无利害,一、interspecific competition,1.concept Interespecific competition: competition between individuals of different species. Types of interespecific competition 1.intereference competition: form of competition involving direct antagonistic interactions between individuals. Such as allelopat

3、hy (他感作用) 2. exploitation competition: consume resources to reduce the fitness of other species In addition there is a competition called Apparent competition: one predator has two preys, the number of predator will increase with the increasing of one prey, in consequence, the number of another prey

4、 will decrease because of the increasing of predator.,3,高斯假Growth curves for Paramecium aurelia and P. caudatumin separate and mixed cultures,说,2.Common characteristics of interspecific competition: 不对称性 ：the consequence is not equal to different species 共轭性：competition of one resource affects the c

5、ompetition of other resources,3. Interspecific competition model：,（1）model： this model was independly addressed by Lotka (1925) and Volterra (1926), respectively. They based this model on the logistic growth model and introduced competition coefficients (12，21).,The effect of interspecific competiti

6、on is incorporated（合并） into the Lotka-Volterra model by -12N2 and - 21N1 The terms 12 and 21 are called competititon coefficients and express the competitive effects of the competing species. 12 is the effect of an individual of species 2 on the rate of population growth of species 1, while 21 is th

7、e effect of an individual of species 1 on the rate of population growth of species 2. If 12 1, then the competitive effect of an individual of species 2 on the population growth of species 1 is greater than that of an individual of species 1.,12 is the effect of an individual of species 2 on the rat

8、e of population growth of species 1 。That is, the resources used by an individual of species 2 are similar to that used by 12 individuals of species 1. for example, the amount of grass fed by a cattle is similar to that fed by ten goats, so 12 is 10. If goat is species 1, cattle is species 2, then12

9、 =10. If there are two cattle and 15 goats, we can regard that there are 2*10+15=35 goats。21 is the effect of an individual of species 1 on the rate of population growth of species 2.,Populations of species 1 and 2 stop growing when,dN1 /dt = r1N1 (1-N1/K1 12N2/K1)=0 dN2 /dt = r2N2 (1-N2/K2 21N1/K2）

10、0 That is :K1-N1-12N2= 0, and K2-N2-21N1 =0,Along the isoclines of zero population Growth, population growth is Stopped, above the line, popula- tion of a species is decresing, Below it the population is in- creasing,In general, the model predicts coexistence of two species when, for both species,

11、interspecific competition is weaker than intraspecific competition. Otherwise, one species is predicted to eventually exclude the other.,The orientation of isoclines for zero population growth and the outcome of competition according to the model,Population growth and population sizes attained by Pa

12、ramecium aurelia and P. caudatum grow separately,Results of interspecies competition,K1K2/，K1/ K2，species 1 wins K1K2/，K1/K2， species 1 and 2 coexist at the crossover point of the isoclines,3）explanation for competitive results 1/K1 and 1/K2 represent intraspecific competition intensity, respectivel

13、y. while/K1 是种群2对种群1的种间竞争强度的指标；/K2称为种群1对种群2的种间竞争强度的指标。 If intensity of interspecific competition is larger than that of intraspecific competition, this species will win. If the intensity of intraspecific competition is larger than that of interspecific competition for both species, these two species

14、 will coexist. If the intensity of interspecific competition is larger than that of intraspecific competition for both species, these two species will have no stable coexistence.,K1K2/，K1/ K2，species 1 wins K1K2/，K1/K2， species 1 and 2 coexist at the crossover point of the isoclines 因为1/K1和1/K2分别为种群

15、1和2的种内竞争强度 /K1是种群2的种间竞争强度的指标；/K2称为种群1的种间竞争强度的指标。 1/K1/K2，/K11/K2，物种2取胜。 1/K1/K2，/K11/K2 ，表示两个物种都是种内竞争强度小于种间竞争，因而出现不稳定的平衡。,5.Gauses hypothesis (competitive exclusion principle),Two species with identical niches cannot coexist indefinitely in the stable environments. If two species coexisted in a regi

16、on for a long time, they will have separation of niches such as diets, activity time, habitats and so on due to the drastic（激烈的）competition. In a word, two species with identical niches cannot coexist indefinitely.,18,Resource partitioning,19,Resource partitioning（分割）,Resource partitioning is demons

17、trated by the feeding habits of five species of North American warblers（刺嘴莺）. Each of these insect-eating species searches for food in different regions of spruce trees.,6. concept of niche Definition：the environmental factors that influence the growth, survival and production of a species. Such as

18、space niche, trophic niche, time niche Fundamental niche基础生态位: defines the physical conditions under which a species might live, in the absence of interactions with other species. Realized niche实际生态位：the actual niche of a species whose distribution is restricted by biotic interactions such as compet

19、ition, predation, disease and parasistism. 广生态位和狭生态位(wide or narrow niche) The concept of niche and Gauses hypothesis can direct introduce of new species,21,Three dimensions of the niche,r,23,种的生态位,24,Fig. The process of character displacement(a) individuals of one species that use resources in regi

20、ons that do not overlap with the other species have a selective advantage.,24,生态位不重叠,26,有关竞争与生态位的两个概念（ ecological release and character displacement ）,生态释放 (ecological release) 种间竞争减弱而引起生态位扩展的现象 生态位压缩： 性状替换 (character displacement) 竞争造成生态分离的证明。Changes in the physical characteristics of a speciess po

21、pulation as a consequence of natural selection for reduced interspecific competition. 注：以上三个概念都与竞争有关。,7.Tilman model and interspecific competition of plants,零增长曲线（ZNGI）,二、捕食作用（Predation）,1. 定义： 捕食one species preys on another species.前者称为捕食者（Predator），后者称为猎物或被食者（Prey）。 狭义的捕食指肉食动物捕食其它动物，广义的捕食还包括食草动物的食

22、草作用，拟寄生（寄生蜂将卵产于其它动物卵中，在幼虫体内生长），同类相食。,(1) preys are the food resources for predators；（2）predators can regulate the population size of preys. In the view of population level, predators restrict the population growth of preys. However, predators can also regulate the population number of preys and impr

23、ove their quality.,2. Relationship between predators and preys,实例： 美国亚利桑那州的黑尾鹿，捕食者为美洲狮和狼。1905年以前黑尾鹿种群为4000头，19071918年捕打捕食者，鹿种群上升到4万头，1925年达到10万头，草场极度退化，1929年又降到4万头，以后降到1万头。 19世纪末，挪威为保护雷鸟，捕猎猛禽和兽类，高密度的雷鸟却引起了球虫病和其它疾病的广泛传播，20世纪初，雷鸟一次又一次大量死亡。,3. Prey-predator population dynamics （1）致命性。如澳洲瓢虫对吹绵介壳虫的防治作用（致

24、命性的）。网捕凶猛鱼类，可使大麻哈鱼数量增加，鱼苗成活率提高了3倍；可使武昌东湖的鱼产量增加。 （2）无关。捕打榛鸡天敌后，仅雏鸡的存活率提高，对秋季种群密度没有明显影响（不显著相关）。 （3）决定性。千里光（植物的花）的数量直接决定捕食者（红棒球蝶灯蛾的幼体）的数量。,33,4. Co-evolution (协同进化) between predator and prey,Characteristics for Predators adapting to preying on preys：锐齿、利爪、尖喙、毒牙等工具，诱饵追击、集体围猎 strategies of preys to escap

25、e being preyed：protective color、alarming coloration、mimesis拟态、假死、集体抵御 Natural opposite selection between preys and predators精明的捕食者。,34,.,Fig. The American bitten are examples of cryptic coloration,35,Fig. a white-tailed ptarmigan.,Prey adaptations,36,5. Lotka-Volterra prey-predator model,assumptions

26、 One species of prey and one species of predator Number of predators is related to that of preys The population of prey can increase at exponential rates without predator, and the population of predator can decrease at exponential rates without prey.,模型：dN/dt = r1N- PN；dP/dt = -r2P+ PN 猎物零增长: r1 N

27、 PN 或 P = r1 / 捕食者零增长： r2P = PN 或 N = r2 / 猎物和捕食者数量交替升降的循环,被食者,40,PREDATOR-PREY RELATIONSHIPS,Population cycles of snowshoe hares and their lynx predators based on the numbers of pelts received by the Hudson Bay Company,41,PREDATOR-PREY RELATIONSHIPS,Out-of-phase fluctuations in laboratory populati

28、ons of the azuli bean beetle and its braconid wasp predator.,42,PREDATOR-PREY RELATIONSHIPS,6. herbivory（广义的捕食现象） 食草作用不同于狭义的捕食作用，食草动物对于许多植物（如高等植物）并不杀死，只取食其中的构件（如部分树叶等）。 Reaction of plant to herbivore （1）mechanistic defense （2）chemical defense,1.概念： 寄生是指一种生物（寄生者,parasite）靠寄生于另一种生物（宿主或寄主,host）的体内或体表而生

29、活。 Parasite: an organism that lives in or on another organism, called the host, deriving benefits from it; parasites typically reduce the fitness of the host, but do not generally kill it.,三、寄生（Parasitism）,共生同一空间中不同物种的共居关系，包括互利共生(mutualism)、偏利共生(commensalism)、原始协作。,四、共生作用（Symbiosis）,定义：interactions

30、between individuals of different species that benefit one species and have no obvious harm to another species 实例：藤本植物附生于乔木的枝上，易获得阳光。,1. 偏利共生（commensalism）,2. 互利共生（mutualism）,definition：interactions between individuals of different species that benefit both partners. 实例：有花植物和传粉动物之间的关系 3. 原始协作 定义：对双方都

31、没有不利影响，或双方都可获得 微利，但协作是松散的。 实例：鸟类与有蹄类的关系。,一、gene pool and gene frequency 二、variation within population and genetic drift 三、natural selection model 四、comparison of two kinds of evolutionary forces 五、types of natural selection 六、 cline (渐变群) 七、 speciation（物种形成） 八、evolutionary strategy,第四节 population ge

32、netics and natural selection,基因库和基因频率,基因库（gene pool）是指种群中全部个体的所有基因的总和。由于存在基因突变，种群基因库的组成是不断变化的。种群中个体的特性就是表现型，它是由基因型的特性和环境影响共同决定的。 Natural selection bases on variation within population. Natural selection mainly depend on differences in the survivorship and reproduction.,一、 gene pool and gene frequenc

33、y,gene frequency 指某一基因在种群中出现的频率。 哈-温定律（Hardy-Weinberg law） in a population mating at random in the absence of evolutionary forces, allele frequencies will remain constant. Radom mating, no mutations, large population size, no immigration, all genotypes have equal fitness,如在染色体相同位置上有两对等位基因A和a，基因频率各为5

34、0%，如果基因平衡不受干扰，种群的基因型频率将稳定为： 25% AA ，50% Aa ，25% aa A a A AA Aa a Aa aa,Test Hardy-Weinberg law,变异和遗传漂变,Natural selection bases on variation within population. Natural selection mainly depend on differences in the survivorship and reproduction. genetic drift: change in allele （等位基因）frequencies due to

35、 chance or random events. Small population size increases the probability that allele frequencies will change from one generation to the next due to chance alone.,二、variation within population and genetic drift,三、适合度fitness （生物质量的数量化）,The number of offspring contributed by an individual relative to

36、the number of offspring produced by other members of population. Ultimately defined as the relative genetic contribution of individual to future generations l与m的乘积，称之为适合度（W： fitness），包括生育和存活对环境的适应。 AA W Aa W aa W,53,补充知识：遗传瓶颈和建立者效应,遗传瓶颈 (Bottleneck Effect) an evolutionary event in which a significan

37、t percentage of a population or species is killed or otherwise prevented from reproducing, and the population is reduced by 50% or more, often by several orders of magnitude. ,Large population drastically reduced by a disaster By chance, some survivors alleles may be over-or under-represented, or so

38、me alleles may be eliminated Genetic drift continues until the population is large enough,55,瓶颈效应,遗传瓶颈, 100%,在原种群中 基因频率 为80%,在越冬种群中 基因频率为50%,在第二年种群中基 因频率就变化为50%,在第三年种群中基因 频率就变化为100%,在越冬种群基 因频率为100%,Bottleneck Effect,56,:,=5:1,:,=5:2,建立者效应Founder effect,自然选择(natural selection)和遗传漂变(genetic drift)是种群进

39、化的两种动力。自然选择是定向的，像筛子一样，保留有利的。 自然选择强度的指标是选择系数（s），决定于种群适合度的差异程度（相对适合度，w）。s=wmax-wmin 。 相对适合度(relative fitness)是个体适合度与最高适合度的比值。w11=W11/Wmax; w12=W12/Wmax; w22=W22/Wmax The intensity of genetic drift depends on population size.用种群大小的倒数作为遗传漂变强度的指标。,四、comparison of two kinds of evolutionary forces,1.稳定选择(s

40、tabilizing selection)：环境条件对靠近种群数量特征分布中间的个体有利，“淘汰”两侧的极端个体，选择属于稳定型的。如出生体重。 2.定向选择(directional selection)：当选择对一侧的“极端”个体有利时，种群的平均值向这一侧移动。这可能是基因型变化最快的一类。大部分人工选择。 3.分裂选择(disruptive selection)：当选择对两侧的“极端”个体有利时，“中间”个体被淘汰，使种群分成两部分。,五、Three types of natural selection,自然选择的类型,稳定选择,”geographical theory of speci

41、ation” was accepted by many researchers. 1. 地理隔离(geographical isolation)：地理屏障将两个种群隔开，种群间个体和基因交流受阻。 2. 独立进化：地理隔离的种群各自独立地进化，适应各自的特殊环境。 3. 生殖隔离机制的建立：two populations established reproductive isolation due to long-term geographic isolation and population variation, then form two species from two populati

42、ons of one species,六、 speciation,63,扩展 分布区,地理隔离,独自 进化,生殖隔离,形成2个 物种,即使相遇 已经不能 相互配育,动物物种形成的方式：异域性物种形成(allopatric speciation)A,大范围地理隔离,64,扩展 分布区,地理隔离,独自 进化,生殖隔离,形成2个 物种,即使相遇 已经不能 相互配育,异域性物种形成B,65,扩展 分布区,独自 进化,生殖隔离,形成2个 物种,即使相遇 已经不能 相互配育,部分的地理隔离 存在基因交流屏障,如生物的运动能力及 繁殖体传播能力差,邻域性物种形成(parapatric speciation)

43、66,生境选择差异 食物选择差异 宿主选择差异,独自 进化,生殖隔离,形成2个 物种,即使相遇 已经不能 相互配育,无地理隔离 但生态位产生差异,虽有基因交流的可能 但生境食物等习性阻止了交流,同域性物种形成(sympatric speciation),67,有关适应辐射(adaptive radiation)图解,如： 分别在 生境(habitat)、 食性(diet)、 取食方式(feeding methods)、 取食时间(time)、 取食空间 (space) 、 取食大小 (size) 多方面 产生差异,68,adaptive radiation of birds,七.Factor

44、s influencing natural selection,.space（spatial variation in ecological factors forms changes of selective pressure） 选择压力在地理空间上的连续变化（如温度、海拔、湿度、光照、污染程度等），导致基因频率或表现型的渐变，形成一变异梯度，称为渐变群(cline)。 .time,.density 低密度条件下，早花种群就会向有一个较高的内禀增长率值进化，而在高密度下，晚花种群倾向于有一个较大的稳定密度即早花比晚花有更大的r值,晚花比早花有更大的值 例如，蒲公英在干扰生境（低密度）中个体小

45、早花，即低密度下利于高r值；未干扰生境个体大、晚花。 .age structure 不同年龄适合度不同，所面临的选择压力也不同 比较，aa，a三种基因型各自的适合度（不同年龄的适合度：即不同年龄的生殖力和存活率）后，自然选择有利于高r值的种群,.形态适应（伯格曼法则、阿伦定律） 2.生理适应（如颤抖性产热） .生殖适应(reproductive adaptation)（最适窝卵数主要看出飞率。生殖上的能量分产卵所用的能量和抚育所用的能量，这就涉及能量如何分配和权衡的问题；此外不同海拔的同种动物窝卵数差异较大，说明生殖对策不同；不同海拔的同种动物所采用的生殖对策也不同，如某些爬行类在高海拔为卵

46、胎生，而低海拔为卵生） .生态适应ecological adaptation（又称生活史对策life history strategy）,八、evolutionary strategy,72,8.1 生活史 (Life history)和生态适应对策,8.1.1 生活史的概念 The adaptations of an organism that influence aspects of its biology such as the number of offspring it produces, its survival, and its size and age at reproduct

47、ive maturity. 8.1.2 生活史的关键组分 身体大小 (body size)、生长率 (growth rate)、繁殖 (reproduction)、寿命 (longevity),8.1.3 生态对策(生活史对策, life history strategy) 生物在生存斗争中获得的生存对策又称生活史对策,74,8.2 r-selection和K-selection,Lack对鸟类的研究 幼鸟存活数：产卵数和亲体关怀能力 ，两者之间的权衡。（一种是低生育力，亲本有良好的育雏行为，另一种是高生育力，没有亲本关怀行为） MacArthur和Wilson按栖息环境和进化对策的生物分类

48、r-对策者生物和K-对策者生物 E. Pianka的r-选择和K-选择理论（列表比较r-选择和-选择的有关特征） r-selection：种群增长率最大；K-selection：种群竞争能力最大,76,R选择与K选择比较,r-选择和K-选择的适应意义 r-selection：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 。如某些害虫、杂草等 K-selection：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。很容易成为濒危动物，如大熊猫、虎。 r-选择以量(quantity)取胜， K-选择以质

49、quality)取胜,78,既是r-对策者又是K-对策者？,Linhart(1974)年曾研究过水苦荬的两个种群,产生少量种子，种子个体大，可以很快萌发,环境多变,环境稳定,产生大量种子，种子个体小,种群死亡率高,临时性池塘,79,下几颗蛋合适？,图片：鸟类窝寄生,80,环境与物种进化,两条道路,遭遇两种环境,？,如何应对,以K-对策者模式应对,以r-对策者模式应对,物种进 化过程,不稳定环境 不可预测 灾变较多,稳定环境 竞争较 为激烈,生物,稳定 环境,r- K-,r- K-,不稳定 环境,稳定 环境,不稳定 环境,生物,r,K,r,K,r-对策者 K-对策者,环境,生物进化方向,81,

50、第五节. Population regulation,外源性种群调节理论 气候学派 (climatic school) 生物学派(biotic school) 内源性自动调节理论 行为调节 (behavior regulation) 内分泌调节 (endocrine regulation) 遗传调节 (genetic regulation),两个基本概念的区别,密度制约因素(density-dependent factor)：Biotic factors in the environment, such as disease and competition, are often called