水域生態(tài)學(xué)：09 種群生態(tài)(modified)

1、Ch.2 種群生態(tài)Population EcologyOutlineProperties of populationDemographyPopulation growthIntraspecific interactionsLife historiesPopulation regulation1. Properties of Populations種群(population) 在一定時(shí)期內(nèi)生活在特定地區(qū)的同一物種個(gè)體的集合種群基本特征：數(shù)量特征空間特征遺傳特征：基因庫(gene pool)種群生態(tài)學(xué)population ecology ：研究種群生長(zhǎng)、波動(dòng)、擴(kuò)散及種內(nèi)、種間相互關(guān)系的科學(xué)時(shí)空變化

2、spatial & temporal changes分布distribution多度abundance種群動(dòng)態(tài)(Population dynamics)是研究核心: 研究種群生態(tài)之目的拯救瀕危種Saving endangered species控制害蟲種群Controlling pest populations管理魚類和游獵種類種群game populations了解和控制流行病disease epidemics種群的群體特性(group characteristics)-統(tǒng)計(jì)量:初級(jí)特性primary characteristics: 密度Density改變種群密度的4個(gè)參數(shù)：出生natal

3、ity (births)死亡mortality (deaths)遷入immigration遷出 emigration次級(jí)特性 Secondary characteristics年齡分布age distribution性比sex ratio遺傳組成genetic composition種群增長(zhǎng)速率population growth rate 空間中個(gè)體分布式型pattern of distribution種群結(jié)構(gòu)Population structure種群表現(xiàn)出動(dòng)態(tài)行為，隨時(shí)間而改變because of births, deaths, and movements of individuals.密

4、度和空間分布the density and spacing of individuals within suitable habitat年齡結(jié)構(gòu) the proportions of individuals in various age classes交配體系mating system遺傳結(jié)構(gòu)genetic structure2.種群參數(shù)Population Parameters密度Density 和 相對(duì)密度 Relative density出生率 Natality 和 死亡率 Mortality遷入 Immigration 和 遷出 Emigration年齡分布 Age distribut

5、ion性比 Sex ratio空間和時(shí)間分布 Spatial & Temporal distribution2.1 Population Density (abundance)單體生物 (unitary organism ) An organism, such as an arthropod or vertebrate, whose growth to adult form follows a determinate pathway, unlike modular organisms whose growth involves indeterminate repetition of units

6、 of structure.構(gòu)件生物 (Modular organism ) A organism which grows by producing additional units of body construction that are very similar to the units of which it is already composed.側(cè)枝構(gòu)件的生長(zhǎng)，示基株original genet及其無性系分株ramets。由于所有 ramets在基因上完全一致，因此 the ramets 一起構(gòu)成 genet. 構(gòu)件生物的例子: (i) duckweed, 隨著生長(zhǎng)分離出ramet

7、s; (ii) grasses, ramets以匍匐枝stolons或根莖rhizomes聯(lián)系; (iii) trees, 以構(gòu)件增加的方式生長(zhǎng)特定(單位)面積或體積生境內(nèi)的個(gè)體數(shù)種群密度Population density粗密度Crude density: The measurement of the number of individuals per unit area生態(tài)密度Ecological density: Density measured in terms of the amount of area available as living space (patch)種群密度的變化

8、特點(diǎn)：種群密度的估算對(duì)種群動(dòng)態(tài)研究非常重要自然條件改變，密度也會(huì)發(fā)生變化種群密度隨生物個(gè)體增大而下降種群大小隨時(shí)間而變化長(zhǎng)期記錄反映出在短期內(nèi)容易被忽視的波動(dòng)密度反映種群與環(huán)境的關(guān)系。通常，資源最豐富的地方個(gè)體最多。Body size and population density of herbivorous mammalsAllee effect(阿利效應(yīng)）: 最大種群增長(zhǎng)出現(xiàn)在中等密度時(shí) maximal population growth may occur at moderate density.密度過低(undercrowding): 配偶困難近親交配導(dǎo)致近交衰退inbreeding密

9、度過高(overcrowding):食物減少 沖突(strife)增加 疾病傳播加快容易被捕食根據(jù)密度可將物種分為：優(yōu)勢(shì)種 (dominant species)常見種 (common species) 稀有種 (rare species) 稀有性 Rarity受以下因素影響 稀有種類容易滅絕 rare species are vulnerable to extinctiongeographic rangehabitat tolerancepopulation sizeCommonness, rarity, and vulnerable to extinction袋獾輻射松三角葉楊厥短葉紫杉千歲

10、蘭最小生存種群Minimum viable population (MVP)最小生存種群：種群在一個(gè)地區(qū)內(nèi)得以維持繁衍的最少個(gè)體數(shù)，或者說種群能夠維持存在一定年限（通常100或1000年）的最小數(shù)量 MVP取決于種群統(tǒng)計(jì)學(xué)特征demographics 種群內(nèi)遺傳多樣性種群密度統(tǒng)計(jì)絕對(duì)密度統(tǒng)計(jì)全部計(jì)數(shù)法 total count :個(gè)體可明顯標(biāo)記的小種群通常用于瀕危種類，特別是大型動(dòng)物如哺乳類、鳥類等抽樣調(diào)查法Sampling methods樣方法Use of quadrats：the general procedure in this technique is to count all the

11、individuals on several quadrats of known size and then to extrapolate the average count to the whole標(biāo)志重捕法Mark-recapture methods： the technique of capture, marking, release, and recapture is an important one for mobile animals, because it allows not only an estimate of density, but also estimates of

12、birth rate and death rate, migration route. Used mainly on larger forms, such as butterflies, snails, beetles, and many vertebrates, that can be readily marked.Petersen methodFor an initial marked sample of size M, a second sample of size n, containing x marked individuals, the population size N is:

13、 N = nM/xIf 20 fish are captured, marked, and returned to a small pond, and a second sample of 50 fish contains 6 marked fish, the population estimate is 50(20)/6 = 167.第二批樣本中標(biāo)記個(gè)體數(shù) m第二批樣本總個(gè)體數(shù) n=標(biāo)記數(shù) M總樣本大小 N標(biāo)記重捕法的3個(gè)重要前提（假設(shè)）標(biāo)記不影響被標(biāo)記動(dòng)物的行為被捕的可能性均等；標(biāo)記與未標(biāo)記動(dòng)物的死亡率一樣Petersen法假定在標(biāo)記-重捕期間沒有死亡率沒有遷移相對(duì)密度Indices of

14、 Relative Density (多度指數(shù)Index of abundance)捕捉數(shù) (Traps) 糞堆數(shù) (Number of fecal pellets)鳴叫頻率 (Vocalization frequency)毛皮收購記錄 (Pelt records) 單位努力捕撈量 (catch per unit fishing effort, CPUE) 活動(dòng)痕跡數(shù) (Number of artifacts)調(diào)查問卷 (Questionnaires)蓋度 (Cover)食量 (Feeding capacity)路旁計(jì)數(shù) (Roadside counts)2.2 出生率和死亡率Natality

15、 & Mortality出生率Natality最大出生率Maximum natality種群處于理想條件下的出生率實(shí)際出生率Realized natality (ecological natality)在特定條件下種群實(shí)際上的出生率出生率取決于生物的特性性成熟速度、每次繁殖量、每年繁殖次數(shù)、一生繁殖次數(shù)等).出生率 Natality潛在繁殖力(Fecundity): 生理學(xué)概念, refers to an organisms potential reproductive capacity (potential fecundity)：懷卵量實(shí)際繁殖力(Fertility): 生態(tài)概念, is b

16、ased on the number of viable offspring produced during a period of time(realized fertility)：產(chǎn)卵量Fecundity 通常與親本護(hù)幼負(fù)相關(guān)死亡率Mortality (存活率survival)壽命longevity:潛在壽命Potential longevity, 某一物種個(gè)體在理想條件下，由生理極限決定所能達(dá)到的最大壽命 (生理壽命physiological longevity )實(shí)際壽命Realized longevity ：現(xiàn)實(shí)環(huán)境條件下個(gè)體的實(shí)際壽命最小死亡率Minimum mortality生態(tài)

17、死亡率Ecological mortality死亡率測(cè)定:直接方法: 如標(biāo)志重捕法間接方法: 如根據(jù)種群年齡組相對(duì)豐度變化的連續(xù)觀測(cè)分析 the relative abundance of successive age groups in the population死亡率Mortality2.3遷入和遷出(Immigration & emigration)種群內(nèi)的個(gè)體移動(dòng)Movements within populations 稱為擴(kuò)散 (dispersal).亞種群之間的個(gè)體移動(dòng)Movements between subpopulations 稱為遷移(migrations), or mo

18、re specifically:遷出emigration (leaving a subpopulation，)遷入immigration (entering a subpopulation)，擴(kuò)散Dispersal擴(kuò)散(散布)-是大多數(shù)生物生活史的必要部分，是局域種群間產(chǎn)生基因流動(dòng)gene flow,防止近交衰退inbreeding的生態(tài)過程。一些種群維持凈遷出，總是輸出個(gè)體，稱為源種群(source populations);另一些種群依靠?jī)暨w入維持存在，稱為匯種群 (sink populations) 散布用標(biāo)志法確定在種群研究中很少測(cè)定遷入和遷出，大多數(shù)情況下假設(shè)兩者相等種群分布種群分布

19、 (distribution of a population) 是指它的地理范圍 geographic range. 這個(gè)范圍內(nèi)可能出現(xiàn)適合和不適合的生境片層(patches).根據(jù)種群分布范圍可將物種分為特有種Endemic species:僅局限于某一地區(qū)或生境分布的物種廣布種cosmopolitan species本地種native (indigenous) species外來種exotic (alien, non-native, non-indigenous) species2.4種群內(nèi)個(gè)體分布型式Dispersion of Individuals within Populations

20、種群內(nèi)個(gè)體分布型式描述個(gè)體相互之間的間隔，反映生境的異質(zhì)性 (heterogeneity) 和種群社會(huì)作用可能的幾種型式:成群分布、成團(tuán)分布 (clumped, aggregated, clustered)均勻分布 (evenly spaced, regular, uniform)隨機(jī)分布 (random)小尺度上，隨機(jī)分布、均勻分布或成團(tuán)分布均有可能；大尺度上, 表現(xiàn)為成團(tuán)分布Dispersion of PopulationClumped dispersionUniform DispersionRandom DispersionCauses of DispersionEven spacing

21、 may arise from direct interactions among individuals:maintenance of minimum distance between individuals or direct competition for limited resources may cause this patternClumped distribution may arise from:social predisposition to form groupsclumped distributions of resourcestendencies of progeny

22、to remain in the vicinity of their parents確定分布型式的方法泊松分布（ Poisson distribution ）V(variance，方差)/M(mean，平均值)If V/M=1, random If V/M=0, even spacing If V/M1, clumpingWhere: x=樣本中含有的個(gè)體數(shù) f=出現(xiàn)頻率（不同個(gè)體數(shù)樣本的出現(xiàn)率） N=樣本總數(shù)2.5 統(tǒng)計(jì)學(xué)方法-生命表Life tables生命表Life table：是一個(gè)種群根據(jù)個(gè)體存活年齡和繁殖力所作的歸納總結(jié)A life table combined with a fe

23、cundity schedules can be used to estimate凈生殖率net reproductive rate (R0)幾何級(jí)數(shù)增長(zhǎng)率geometric rate of increase ()指數(shù)增長(zhǎng)率per capital rate of increase (r)Life tables動(dòng)態(tài)生命表 (dynamic life table cohort, a generation, age-specific or horizontal life table) 根據(jù)跟蹤觀察一群同一時(shí)間出生的(同齡群，cohort)生物的死亡或存活動(dòng)態(tài)過程獲得的數(shù)據(jù)來編制的生命表. 難于應(yīng)用到

24、運(yùn)動(dòng)和（或）長(zhǎng)壽的動(dòng)物種群中cohort methodfollow group of individuals born at same time through all ages until death. In practice this is very difficult to do if organisms are long-lived.Assumptions:1) No emigration or immigration.2) Sample being followed is representative of entire population.Two procedures:1) Fo

25、llow survival, problem is it combines both deaths and emigration.2) Unlocated individuals counted as deaths.Life tables靜態(tài)生命表( static life table, stationary, time-specific, current, or vertical life table,) 根據(jù)某一特定時(shí)間，對(duì)種群作一個(gè)年齡結(jié)構(gòu)的調(diào)查，并根據(jù)其數(shù)據(jù)編制的生命表.要求具備確定個(gè)體年齡的一些方法。假定種群所經(jīng)歷的環(huán)境年復(fù)一年是沒有變化的。綜合生命表 (Composite life

26、 table )Life tables summarize demographic information (typically for females) in a convenient format, including:age (x)number alive at age x (nx)survival of newborn individuals to age x (age-specific survival rate lx): proportion of individuals of age x dying by age x+1 ( mx)proportion of individual

27、s of age x surviving to x+1 ( sx)fecundity at age x ( bx)expectation of further life of individuals of age x2.6 內(nèi)稟增長(zhǎng)率The Intrinsic Rate of Increase馬爾薩斯參數(shù) (Malthusian parameter )或內(nèi)稟增長(zhǎng)率 (能力)(intrinsic rate of increase, innate capacity for increase) (rm): 是一個(gè)具有穩(wěn)定年齡結(jié)構(gòu)的種群，在穩(wěn)定條件下(理想條件下)的指數(shù)增長(zhǎng)率。內(nèi)稟增長(zhǎng)率（能力）決定于

28、生殖能力、壽命和發(fā)育速度內(nèi)稟增長(zhǎng)率計(jì)算方法rm 通過在生命表上，從各年齡組凈生殖率R0開始，經(jīng)過幾步計(jì)算獲得近似值。凈生殖率 (net reproductive rate, R0)是一個(gè)個(gè)體整個(gè)生命中后代總數(shù)的期望值R0=lxbxR0 = 1 表示種群穩(wěn)定替代R0 1 表示種群增長(zhǎng)內(nèi)稟增長(zhǎng)率計(jì)算方法種群世代時(shí)間 (generation time ) T = xlxbx /lxbx內(nèi)稟增長(zhǎng)率決定于凈生殖率和世代時(shí)間:rm= loge R0/ TR0大、T小，導(dǎo)致種群增長(zhǎng)最快2.7年齡結(jié)構(gòu) (Age Structure)一個(gè)種群中每一年齡級(jí)個(gè)體數(shù)的比例，稱為該種群的年齡結(jié)構(gòu)(age structu

29、re).種群的年齡分布反映存活、繁殖史和未來增長(zhǎng)的潛力。Environmental factorsNatality ratesMortality ratesAge compositionRate of increase or decrease of the populationThe age distribution of a white oak, Quercus alba, population in Illinois (data from Miller 1923)The age distribution of a population of Rio Grande cottonwoods (

30、三葉楊), Populus deltoides subsp. wislizenii, near Belen, New Mexicon (data from Howe and Knopf 1991)出生率等于死亡率，數(shù)量達(dá)到穩(wěn)定 (constant size)的種群，將保持一定的(fixed)年齡結(jié)構(gòu)，稱之為固定年齡分布 (stationary age distribution), 并維持這種分布。當(dāng)特定年齡(age-specific)的出生率和死亡率固定不變，種群呈指數(shù)增長(zhǎng)(grow exponentially)時(shí)，種群保持穩(wěn)定的(constant)年齡結(jié)構(gòu)，稱之為穩(wěn)定年齡分布(stable

31、age distribution)。Age distribution for human populations in countries with stable, declining, and growing populations (data from the U.S. Bureau of the Census, International Data Base)立陶宛(continued) Declining population匈牙利(continued) Growing population盧旺達(dá)2.8 存活曲線 (Survivorship Curves)存活曲線概括一個(gè)種群的存活型式

32、.當(dāng)個(gè)體傾向于活到生理年齡時(shí)，在前期有高的存活率，接近生理年齡時(shí)死亡率急劇升高，存活率呈明顯的凸形 convex, 是為型。典型的型曲線出現(xiàn)于人類、其他哺乳動(dòng)物以及一些植物如果各齡死亡率穩(wěn)定，存活曲線接近直線 straight，是為型號(hào)。II 型曲線是成年鳥類、嚙齒類、爬行類以及多年生植物的典型特征如果在早期死亡率很高，則曲線呈凹形concave，是為III型。如牡蠣、魚類、大多數(shù)無脊椎動(dòng)物和一些植物Three types of survivorship curvesAge 2.9 性比 Sex Ratio種群中的性比顯著影響繁殖潛力，在脊椎動(dòng)物中也影響種群內(nèi)的社會(huì)關(guān)系性比因繁殖方式而變 Re

33、productive modes:asexual reproduction: clone, gynogenesis(雌核生殖)bisexual: polygamy (polyandry, polygyny); monogamy; hermaphrodite (雌雄同體)sex reversal (性反轉(zhuǎn))性比 Sex Ratio環(huán)境因素Environmental cues影響性比溫度：揚(yáng)子鱷(the Yangzi alligator)29-32, 1:1at 34.5, all male26-27.5, most female. 生活條件：生活條件良好時(shí)增加雌性個(gè)體以增強(qiáng)種群的繁殖力；反之增加

34、雄性個(gè)體以降低繁殖力3. 種群增長(zhǎng)Population growthPopulation sizeBirth (B)Death (D)Immigration (I)Emigration (E)+N t1 N t B D3.1 幾何增長(zhǎng)Geometric Growth起始種群數(shù)量t 時(shí)間時(shí)種群數(shù)量 時(shí)間間隔, in hours, days, years, etc 一個(gè)時(shí)間間隔內(nèi)每個(gè)個(gè)體平均后代數(shù)量（周限生長(zhǎng)率）離散種群discrete reproduction populations的生長(zhǎng)：世代間不重疊，可用幾何模型來描述種群生長(zhǎng)N(t+1) = N (t)3.2 指數(shù)增長(zhǎng)Exponential

35、 Growth 連續(xù)種群Continuous population的生長(zhǎng)： 無環(huán)境條件限制下，指數(shù)增長(zhǎng)（J型曲線, J-shape curve）Anatomy of equations for exponential population growtht 時(shí)間的數(shù)量 時(shí)間間隔：日、年等瞬時(shí)增長(zhǎng)率起始數(shù)量dN/dt = r N(finite rate of increase, 周限增長(zhǎng)率) = 后一時(shí)間種群數(shù)量與前一時(shí)間種群數(shù)量之比 = N(t+1)/N(t)r (instantaneous growth rate, 瞬時(shí)增長(zhǎng)率，exponential growth rate, 指數(shù)增長(zhǎng)率）兩者

36、的關(guān)系： = e r loge = rA population is:growing when 1 or r 0constant when = 1 or r = 0declining when 0) or r 0種群倍增時(shí)間(Doubling time): 種群數(shù)量加倍所需的時(shí)間=0.6931/r3.3 邏輯斯諦增長(zhǎng) Logistic growth有限環(huán)境條件下連續(xù)種群增長(zhǎng)方式可用邏輯斯諦增長(zhǎng)方程描述(S型曲線,sigmoid curve)種群數(shù)量負(fù)載力(容納量)內(nèi)稟增長(zhǎng)率數(shù)量變化時(shí)間變化Intrinsic rate of increase is the maximum per capita

37、rate of increase, achieved by a species under ideal environmental conditions種群增長(zhǎng)的基本理論模型J-型增長(zhǎng)S-型增長(zhǎng)環(huán)境容納量Carrying capacity：環(huán)境所能支持的某一特定種群的個(gè)體數(shù)。(1-N/K) 是種群繼續(xù)增長(zhǎng)的機(jī)會(huì)(the further opportunity for population growth)，也稱剩余空間(residual space).種群增長(zhǎng)率（種群潛在的最大增長(zhǎng)）（最大增長(zhǎng)的可實(shí)現(xiàn)程度）邏輯斯諦方程的積分式：邏輯斯諦曲線常被劃為5個(gè)時(shí)期開始期(initial phase)，也

38、可稱為潛伏期(latent phase)加速期(accelerating phase)轉(zhuǎn)折期(inflecting phase)在 N=K/2時(shí)，加速度等于0，出現(xiàn)轉(zhuǎn)折點(diǎn)(inflection point )。減速期(decelerating phase)飽和期(asymptotic phase)邏輯斯諦方程的應(yīng)用最大持續(xù)產(chǎn)量 (maximum sustainable yield，MSY ) 在不減少種群數(shù)量，即種群補(bǔ)充量等于或超過采收量的前提下，可以從種群中采收的最大個(gè)體數(shù)量，MSY=rK /43.4 種群的時(shí)空動(dòng)態(tài)Temporal and Spatial Dynamics of Popul

39、ations種群平衡Population equilibrium: 取決于種群的恢復(fù)力(resilience) 不規(guī)則波動(dòng)Irregular fluctuation 混沌 (chaos)規(guī)則或周期性波動(dòng)Regular or cyclic fluctuation, 振蕩(oscillation)種群下降Population decline種群的時(shí)空動(dòng)態(tài)種群爆發(fā)Population outbreak: 超越overshooting種群崩潰Population crash (collapse): 過渡補(bǔ)償overcompensationPopulation cycles result from ti

40、me delays (time lag, 時(shí)滯): A delay in the response of a population (or other system) to conditions of the environment.Logistic growth curve and examples of fluctuations around K種群滅絕Population extinction：確定性滅絕deterministic extinction; 隨機(jī)性滅絕stochastic extinction背景滅絕Background extinction 反映的是當(dāng)生態(tài)系統(tǒng)變化，一些物

41、種消失，另一些物種取而代之的事實(shí)，其發(fā)生率相對(duì)較低，是自然世界的正常特性。大規(guī)模滅絕Mass extinction 指由于自然災(zāi)害natural catastrophes，如火山爆發(fā)volcanic eruptions、颶風(fēng)hurricanes、干旱 droughts、或流星碰撞meteor impacts等所造成的大量物種的相繼死亡.人類造成的滅絕Anthropogenic extinction 在受影響的物種數(shù)量、全球尺度和災(zāi)難性質(zhì)上與大規(guī)模滅絕一樣。4. 種內(nèi)關(guān)系Intraspecific Interactions同種相殘 (Cannibalism)：A intraspecific co

42、nsumer-resource interaction in which individuals consume other individuals of the same species. e.g., northern pike(狗魚)利他行為 (Altruism) A social interaction that enhances the fitness of an unrelated recipient while reducing the fitness of the donor. e.g. rabbit 寄生 (Parasitism)：Individuals live in clo

43、se association, to cost of host. e.g. anglerfish(角鮟鱇)Female anglerfish (Edriolychnus schmidti) with two parasite males競(jìng)爭(zhēng) (Competition )：Use or defense of a resource by one individual that reduce the availability of that resource to other individuals.爭(zhēng)奪競(jìng)爭(zhēng) (contest competition):Successful individuals

44、divide the resource and the unsuccessful are denied access to it. Contest competition is characteristic of species whose individuals are able to defend a resource from others.分?jǐn)偢?jìng)爭(zhēng) (scramble competition ): All individuals have equal access to the resource, and each attempts to get a part of it. In ex

45、treme cases, scramble competition results in each individual obtaining insufficient amounts to survive or reproduce. 爭(zhēng)奪競(jìng)爭(zhēng)和分?jǐn)偢?jìng)爭(zhēng)競(jìng)爭(zhēng)曲線示意圖 (A) 和資源分配型式圖(B)。實(shí)線表示爭(zhēng)奪競(jìng)爭(zhēng)，虛線表示分?jǐn)偢?jìng)爭(zhēng)，圖B中點(diǎn)線表示存活所需最小資源量。Initial DensityNumber of SurvivorsALog Individual Resource Intake for SurvivorsInitial DensityMinimum Requirement f

46、or SurvivalB集群 (Schooling) 種群內(nèi)個(gè)體由社會(huì)引力形成團(tuán)體，集群的成員通常同種、同樣大小和年齡，以同一方向沿著相似路徑統(tǒng)一移動(dòng)。Members of the school are usually of the same species, size, and age, and move in unison along parallel paths in the same direction.Advantages:提高繁殖成功率Improving breeding success有利于尋找食物Beneficial to searching food有助于防御被捕食Helpf

47、ul to defending from predation有益于遷徙（洄游）Conducive to migrationDisadvantages: 破壞食物資源Destroying food resources易招致捕食者攻擊Prone to attack by predators 5. 生活史概述（Life History）出生、生長(zhǎng)、分化、繁殖、衰老、死亡從出生到死亡所經(jīng)歷的全部過程。life history，life cycle為遺傳物質(zhì)所決定，一般不能改變，但具一定的可塑性(plasticity)e.g.種子數(shù)量、大小、個(gè)體大?。ㄖ仓旮甙┑认嚓P(guān)性（某些遺傳特性受另一些特性的限制，

48、e.g. 大小成熟期；大小壽命）生活史特性(Life History Traits)個(gè)體大小(Size)生長(zhǎng)型式(Growth Pattern)性成熟年齡和大小(Age & Size at Maturity)后代數(shù)量、大小和性比(Number, Size and Sex-ratio of Offspring)特定年齡和大小繁殖投入 (Age- and Size-specific Reproductive investment)特定年齡和大小死亡進(jìn)程(Age- & Size-specific Mortality Schedule)壽命(Length of Life)生活史理論 Life-hist

49、ory theoryBecause all organisms have access to limited energy and other resources, there are trade-offs (權(quán)衡)between the number and size of offspring (large, few eggs vs small, many eggs)Reproduction vs growth Current reproduction vs survivalcurrent reproduction vs future reproduction （Semelparity vs

50、 iteroparity） Life history theory predictionWhere adult mortality is higher, natural selection will favor early maturity and more reproductive effort; and where adult mortality is low, natural selection has been expected to favor delaying maturity and less reproductive effort. Reproductive effort is

51、 the allocation of energy, time, and other resources to the production and care of offspring.The great diversity of life histories may be classified on the basis of a few population characteristics, such as fecundity or number of offspring, survival, and age at maturity.r-selection(r-strategist): Selection on traits that determine fecundity and survival to favor rapid population growth (r) at low population densities. K-selection(K-strategist). Selection on traits that determine fecundity and survival to favor competitive ability at densities near the carrying capacity (K). r