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1、Chapter 10Predation 2002 by Prentice Hall, Inc.Upper Saddle River, NJ 07458OutlineThere are a variety of antipredator adaptations, which suggests that predation is important in naturePredator-prey models can explain many outcomesField data suggests that predators have a large impact on prey populati
2、ons2Chapt. 10OutlineExperiments involving the removal or introduction of exotic predators provide good data on the effects of predators on their preyField experiments involving the manipulations of native populations show predation to be a strong force3Chapt. 10Equilibrium theories of population reg
3、ulationA. Extrinsic biotic school1. Food supply and population regulation2. Predation and population regulation3. Disease and populationB. Intrinsic school1. Stress and territoriality2. Genetic polymorphism hypothesis3. Dispersal4Chapt. 10The causes of population changekey factor analysis 主導因子分析主導因子
4、分析(一一) Density-dependent factor 密度制約密度制約因子因子:(種內、種間因素種內、種間因素)作用強度隨種群密度而變。作用強度隨種群密度而變。A factor affecting population size whose intensity of action varies with density.(二二) )Density independent factor非密度制非密度制約因素約因素 (外界環境因素外界環境因素): having an influence on individuals that does not vary with the number o
5、f individuals per unit area in the population. 5Chapt. 10Density-dependent factor 密度制約因子密度制約因子: 1. 種間因素種間因素.食物、空間資源食物、空間資源 種內、種間競爭種內、種間競爭.病蟲害傳播速度病蟲害傳播速度.個體成熟速度個體成熟速度.體質和繁殖力、生長發育、自相殘殺、外遷體質和繁殖力、生長發育、自相殘殺、外遷.植物結實數量植物結實數量.抗逆性抗逆性在橡樹蛾的生活史裡，有不同的生活環境，不同的掠在橡樹蛾的生活史裡，有不同的生活環境，不同的掠食者食者,寄生、競爭、環境壓力，在不同時期裡會有不同寄生、競
6、爭、環境壓力，在不同時期裡會有不同的死亡率。的死亡率。 6Chapt. 102.種間因素種間因素.競爭競爭.掠食、寄生掠食、寄生.遺傳反饋機制遺傳反饋機制(抗病種的培育抗病種的培育)澳洲野兔澳洲野兔 粘液病毒粘液病毒 抗病種抗病種 7Chapt. 10Density independent factor.氣候因素氣候因素.土壤因素土壤因素.營養營養.理化理化.空間空間.汙染汙染8Chapt. 10Extrinsic factors:External factors acting on populations . Predation, parasitism. Competition for fo
7、od density depended. Competition for space density depended. Random stochastic change density independent. Weather 9Chapt. 101.種內因素種內因素種群是一個具有自我調節種群是一個具有自我調節 (self regulation)機制的生活系統，可以機制的生活系統，可以按照自身的性質及環境狀況調節它們的數量。按照自身的性質及環境狀況調節它們的數量。植物的自疏現象植物的自疏現象禾本科植物的分的產生和生長禾本科植物的分的產生和生長遺傳特性遺傳特性(抗逆性抗逆性)內分泌調節內分泌調
8、節(旅鼠旅鼠)Crowding stress 腎上腺髓質腎上腺髓質(adrenocorticotropin) 腦下腺腦下腺 (Epinephrine) 腎上腺皮質腎上腺皮質(Corticoids) 危急反應危急反應 Alarm response 10Chapt. 10IntroductionWolves in Yellowstone Park (Figure 10.1) U.S. Fish and Wildlife Service, 1980sReintroduce in Yellowstone Park and stabilize wolf populations in Minnesota
9、and MontanaConcernsCattle ranchers concerned: Decimate herd?Are predators tied to the health of the main prey?Can predators switch prey? Ramifications to reestablishmentResults: No major effects11Chapt. 10IntroductionPredationTraditional view: carnivoryDifferences from herbivoryHerbivory is non-leth
10、alDifferences from parasitismIn parasitism, one individual is utilized for the development of more than one parasite12Chapt. 10IntroductionPredation (cont.)Predator-prey associationsFigure 10.2IntimacyLowHighParasiteParasitoidsGrazerPredatorLethalityHighLow13Chapt. 10Antipredator AdaptationsAposemat
11、ic or warning colorationAdvertises an unpalatable tasteEx. Blue jays and monarch butterfliesCaterpillar obtains poison from milkweed14Chapt. 10Antipredator AdaptationsEx. Blue jays and monarch butterflies (cont.)Blue jays suffer violent vomiting from ingesting caterpillarEx. Tropical frogsToxic skin
12、 poisonsFigure 10.3a15Chapt. 10Antipredator AdaptationsCamouflageBlending of organism into background colorGrasshoppers (Figure 10.3b)16Chapt. 10Antipredator AdaptationsCamouflage (cont.)Stick insects mimic twigs and branchesZebra stripes: blend into grassy backgroundMimicry17Chapt. 10Antipredator A
13、daptationsMimicry (cont.) Animals that mimic other animalsEx. Some hoverflies mimic wasps Mimicry Types of mimicryMllerian mimicryFritz Mller, 1879Unpalatable species converge to look the same18Chapt. 10Antipredator AdaptationsUnpalatable species converge to look the same (cont.)Reinforce basic dist
14、asteful designEx. Wasps and some butterfliesMimicry ring: a group of sympatric species, often different taxa, share a common warning patternBatesian mimicryHenry Bates, 1862Mimicry of unpalatable species by palatable species19Chapt. 10Antipredator AdaptationsBatesian mimicry (cont.)Ex. hoverflies re
15、semble stinging bees and wasps (Figure 10.3d)20Chapt. 10Antipredator AdaptationsDifficulty distinguishing type of mimicryMonarch butterflies and viceroy butterflies (Figures 10.3d,e)21Chapt. 10Antipredator AdaptationsDisplays of intimidationEx. Toads swallow air to make themselves appear largerEx. F
16、rilled lizards extend their collars to produce the same effect (Figure 10.3f)22Chapt. 10Antipredator AdaptationsPolymorphismTwo or more discrete forms in the same populationColor polymorphismPredator has a preference (usually the more abundant form)Prey can proliferate in the rarer form23Chapt. 10An
17、tipredator AdaptationsColor polymorphism (cont.)Ex. leafhopper nymphs (orange and black)Ex. Pea aphids (red and green)Reflexive selectionEvery individual is slightly differentExamples: brittle stars, butterflies, moths, echinoderms, and gastropods24Chapt. 10Antipredator AdaptationsReflexive selectio
18、n (cont.)Thwart predators learning processesPrey phenologically separated from predatorEx. Fruit batsEither diurnal or nocturnalOnly nocturnal in the presence of predatory diurnal eagles25Chapt. 10Antipredator AdaptationsChemical defenseUsed to ward off predatorsEx. bombardier beetlesPossess a reser
19、voir of hydroquinone and hydrogen perioxideWhen threatened, eject chemicals into “explosion chamber”26Chapt. 10Antipredator AdaptationsEx. bombardier beetles (cont.)Mix with peroxidase enzymeMixture is violently sprayed at attackerMastingSynchronous production of many progeny by all individuals in p
20、opulation27Chapt. 10Antipredator AdaptationsMasting (cont.)Satiate predatorsAllows for some progeny to surviveCommon to seed herbivoryEx. 17-year and 13-year periodical cicadas28Chapt. 10Antipredator AdaptationsComparison of defense mechanismsTable 10.1, chemical defense is most common29Chapt. 1030C
21、hapt. 10Predator-Prey ModelsEffects of predators on preyDepend on such things as prey and predator densities, and predator efficiencyGraphical method to monitor relationship31Chapt. 10Predator-Prey ModelsGraphical method to monitor relationship (cont.)Prey isoclines have characteristic hump shapeFig
22、ure 10.432Chapt. 10Prey increasei) Prey iscolineKNNNNK111222ii) Predator iscolinePrey densityPredator increasesPredator decreasesPredator densityPredator density33Chapt. 10Predator-Prey ModelsPrey isoclines have characteristic hump shape (cont.)In the absence of predators, prey density would be equa
23、l to the carrying capacity, K1Lower limit, individuals become too rare to meet for reproduction34Chapt. 10Predator-Prey ModelsPrey isoclines have characteristic hump shape (cont.)Between these two values, prey population can either increase or decrease depending on predator densityAbove the isocline
24、, prey populations decline35Chapt. 10Predator-Prey ModelsPrey isoclines have characteristic hump shape (cont.)Below the isocline, prey populations increasePredator isoclinesThreshold density, where predator population will increasePredator population can increase to carrying capacity36Chapt. 10Preda
25、tor-Prey ModelsPredator isoclines (cont.)Mutual interference or competition between predatorsMore prey required for a given density predatorPredator isoclines slopes toward the rightSuperimpose prey and predator isoclinesFigure 10.537Chapt. 10Predator-Prey ModelsSuperimpose prey and predator isoclin
26、es (cont.)One stable point emerges: the intersection of the linesThree general casesInefficient predators require high densities of prey (Figure 10.5a)38Chapt. 10Damped oscillationsPreyisoclinePredatorisoclinea)39Chapt. 10Predator-Prey ModelsThree general cases (cont.)A moderately efficient predator
27、 leads to stable oscillations of predator and prey populations (Figure 10.5b)40Chapt. 10Stable oscillationsPopulation densityPredator equilibrium densityb)41Chapt. 10Predator-Prey ModelsThree general cases (cont.)A highly efficient predator can exploit a prey nearly down to its limiting rareness (Fi
28、gure 10.5c)42Chapt. 10Increasing oscillationsPredator densityc)43Chapt. 10Predator-Prey ModelsAll based on how efficient predator isShift in isoclinesPrey starvation (shift to left)Food enrichment (shift to right) (Figure 10.5d)44Chapt. 10K1increases to K1* with enrichmentPreyPredatorPredator isocli
29、ne remains unchanged“The paradox of enrichment”Prey isoclinechangesK1K1*d)45Chapt. 10Predator-Prey ModelsFood enrichment (shift to right) (cont.)Carrying capacity changesPredator isocline changes “paradox enrichment” : Increases in nutrients or food destabilizes the system46Chapt. 10Predator-Prey Mo
30、delsFunctional responseHow an individual predator responds to prey density can affect how predators interact with prey (Figure 10.6)47Chapt. 10IIIIIINumber of prey eaten per predatorPrey density48Chapt. 10Predator-Prey ModelsFunctional response (cont.)Three typesType I: Individuals consume more prey
31、 as prey density increasesType II: Predators can become satiated and stop feeding, or limited by handling time.49Chapt. 10Predator-Prey ModelsThree types (cont.)Type III: Feeding rate is similar to logistic curve; low at low prey densities, but increases quickly at high densitiesChanges in prey cons
32、umptionFunctional response changes (Figure 10.7)50Chapt. 10Predator-Prey ModelsFunctional response changes (cont.)Dictates how individual predators respond to prey populationNumerical response changesGoverns how a predator population migrates into and out of areas in response to prey densities51Chap
33、t. 10Field Studies of Predator-Prey InteractionsField comparisons to modelsDo predators control prey populations?Importance of predators in controlling prey densityKaibab deer herdKaibab Plateau (Northern Arizona)52Chapt. 10Field Studies of Predator-Prey InteractionsKaibab deer herd (cont.)Declared
34、a national park around 1900All big predators were removed and deer hunting was prohibitedEstimates of 10 fold increase in deer populationReevaluated by Graham Caughley (1970)53Chapt. 10Field Studies of Predator-Prey InteractionsReevaluated by Graham Caughley (1970) (cont.)Predator control had some i
35、mpact; cessation of hunting and removal of competing sheep and cattle also had an impactSerengeti plains of eastern AfricaLarge predators have little effect on large mammal prey54Chapt. 10Field Studies of Predator-Prey InteractionsSerengeti plains of eastern Africa (cont.)Most prey taken are either
36、injured or senileContribute little to future generationsPrey are migratoryMoose population on Michigans Isle Royale55Chapt. 10Field Studies of Predator-Prey InteractionsMoose population on Michigans Isle Royale (cont.)Wolf-free existence until 1949.Durwood Allen (1958) began to track wolf and moose
37、populationsTrends in populations (Figure 10.8)56Chapt. 106001020304050Wolves195519601965197019751980198519901995 1997MooseWolvesYear200400600800100012001400160018002000220024002600Moose057Chapt. 10Field Studies of Predator-Prey InteractionsTrends in populations (cont.)Wolf populationPeaked at 50 in
38、1980Severe nosedive in 1981Small recovery in the late 1990sMoose populationIncreased steadily in the 1960s and 1970sDeclined as the wolf population increased until 198158Chapt. 10Field Studies of Predator-Prey InteractionsMoose population (cont.)A record population of 2500 was reached in 1995, when
39、the wolf population was lowGood evidence of prey population control by predatorsConfounded in 1996 when the moose population crashed - starvation59Chapt. 10Field Studies of Predator-Prey InteractionsCanada lynx and snowshoe harePopulations show dramatic cyclic oscillations every 9 to 11 years (Figur
40、e 10.9)60Chapt. 102040608010012020406080100120140160180200Abundance of lynxAbundance of haresAbundance of lynx (x 1000)Abundance of hares (x 1000)185018601870188018901900191019201930194061Chapt. 10Field Studies of Predator-Prey InteractionsCanada lynx and snowshoe hare (cont.)Cycle has existed as lo
41、ng as records have existed (over 200 years)An example of intrinsically stable predator-prey relationship62Chapt. 10Introduced PredatorsMethod for determining the effects of predatorsDingo predations on kangaroos in AustraliaDingoIntroduced speciesLargest Australian carnivore63Chapt. 10Introduced Pre
42、datorsDingo (cont.)Predator of imported sheepEliminated from certain areasSpectacular increases in native species160 fold increase in red kangaroosOver 20 fold increase in emus64Chapt. 10Introduced PredatorsDingo (cont.)Effects on feral pigsShortage of young pigsConsiderable impact on recruitment of
43、 pigs (Figure 10.10)65Chapt. 100604020204060Age class (years)Males (%)Females (%)0604020204060Males (%)Females (%)6+5-64-53-42-31-20.5-1.056+5-64-53-42-31-20.5-1.05Age class (years)(a) Dingoes present(a) Dingoes present66Chapt. 10Introduced PredatorsEuropean foxes and feral cats in AustraliaDamage d
44、omestic livestockEffects when removed (Figure 10.11)67Chapt. 100204060Predators shotNo shooting19811982Mean no. of rabbits per km of transect68Chapt. 10Introduced PredatorsLamprey and the Great LakesConstruction of Wetland Canal allowed lamprey to enter the Great LakesDramatic reduction in lake trou
45、t (Figure 10.12)69Chapt. 10Lake HuronMean production765432107654321076543210Lake MichiganLake SuperiorMean productionMean production1930 1935 1940 1945 1950 1955 1960Lake trout production (millions per pound)70Chapt. 10Introduced PredatorsLamprey and the Great Lakes (cont.)Trout recovered after lamp
46、rey population was reduced71Chapt. 10Field Experiments with Natural SystemsLions in South AfricaKruger National Park, 1903Lions ShotNumber of large prey increasedShooting of lions ends, 1960Wildebeast increase so much that their numbers had to be culled from 1965 to 197272Chapt. 10Field Experiments
47、with Natural SystemsGray partridge, European game birdFigure 10.1373Chapt. 10Field Experiments with Natural SystemsGray partridge, European game bird (cont.)Over 20 million shot in Great Britain in the 1930sOnly 3.8 million shot in the mid-1980sHigh chick mortality due to starvation74Chapt. 10Field
48、Experiments with Natural SystemsOnly 3.8 million shot in the mid-1980s (cont.)Reduced insects due to introduction of herbicides in the 1950s was suspectedHowever, smaller populations in areas where there was no control of predators by gamekeepers75Chapt. 10Field Experiments with Natural SystemsOnly
49、3.8 million shot in the mid-1980s (cont.)Predation control increasedThe number of partridges that bred successfullyThe average size of the broodsPartridge populations by 75 %76Chapt. 10Field Experiments with Natural SystemsPredators and rodents in FinlandLarge scale removal of predators, April 1992
50、and 1995 over 2-3 km2Large increase in rodent population by June (compared to control plots) (Figure 10.14)77Chapt. 10AprilJuneAprilJune3.532.521.510.503.532.521.510.50Without predatorsWith predatorsMean number of rodents per sampleMean number of rodents per sample78Chapt. 10Applied EcologyHumans as
51、 predators - whalingExploitation necessaryIs harvesting at any level sustainable?History of Antarctic whalingFigure 179Chapt. 10Applied EcologyHistory of Antarctic whaling (cont.)1930s, blue whales primarily harvested1950s, blue whale population depleted, replaced with fin whale1960s, fin whale popu
52、lation collapsed80Chapt. 10Applied EcologyHistory of Antarctic whaling (cont.)1960s, humpback whale population collapsedPrior to 1958, Sei whales hardly ever harvestedReduction in other whales made Sei whale attractive81Chapt. 10Applied EcologyPrior to 1958, Sei whales hardly ever harvested (cont.)P
53、eak harvest of about 20,000 by 1964-65Catches declined thereafter due to limitationsThe relatively small minke whaleWas ignored in the southern oceans until 1971-7282Chapt. 10Applied EcologyThe relatively small minke whale (cont.)Began to be taken, and is now the largest component of the southern ba
54、leen whale catchWhale ban proposed in 1985-86, took effect in 198883Chapt. 10Applied EcologyIceland, Norway, and Japan, 1994Argued for resumption of limited commercial whalingShould we ban commercial whaling?Whale populations are recovering84Chapt. 10Applied EcologyWhale populations are recovering (
55、cont.)Ex. Blue whale populations have increased four foldEx. California grey whales have recovered to prewhaling levels85Chapt. 10SummaryPredation is a strong selective force in natureAposematic colorationCamouflageBatesian and Mullerian mimicryIntimidation displaysPolymorphisms86Chapt. 10SummaryPre
56、dation is a strong selective force in nature (cont.)Chemical defensesModeling predator-prey interactionsEven simple predator-prey models show87Chapt. 10SummaryEven simple predator-prey models show (cont.)Stable cyclesWildly increasing and unstable oscillationsDifficulty in predicting or modeling how
57、 predators and prey interactMutual interference between predators88Chapt. 10SummaryDifficulty in predicting or modeling how predators and prey interact (cont.)Existence of specific predator territory sizesAbility of predators to feed on more than one type of prey89Chapt. 10SummaryLarge-scale observa
58、tions supportPredators only take weak and sickly individualsPrey populations influence predator numbers, not vice versa90Chapt. 10SummaryAccidental or deliberate introductions of exotic predatorsProfound effects on native prey populationsPredators have important regulatory effects on prey91Chapt. 10
59、SummaryAccidental or deliberate introductions of exotic predators (cont.)May not be indicative of “natural systems”92Chapt. 10SummaryEvidence from natural systemsMost studies have concluded that predators have a significant effect on prey93Chapt. 10Discussion Question #1Should ranchers be concerned
60、about the reintroduction into their vicinity of large predators, like wolves and panthers?94Chapt. 10Discussion Question #2Do sea lions, otters, or dolphins decrease the stock of fish available for people that fish?95Chapt. 10Discussion Question #3Would the number of deer available for hunters be th
61、e same in the presence of large predators?96Chapt. 10Discussion Question #4What data would you need to collect to answer the above 3 questions?97Chapt. 10Discussion Question #5What can the effects of exotic predators tell us about the strength of predation? What cant they tell us?98Chapt. 10Discussi
62、on Question #6Which do you think more likely: that predators control prey populations or that prey control predator populations? Would the answer vary according to the particular system? Give an example.99Chapt. 10Discussion Question #7What shortcomings do you think Rosenzweig and MacArthurs predato
63、r and prey isoclines have? What would these shortcomings mean in terms of determining how predators and prey interact?100Chapt. 10Discussion Question #8A great many fish stocks seem to have been overfished. How do you think we could prevent overfishing? What biological information do we need to have
64、, and how can we get it when we cant see the population in question?101Chapt. 10Predator-Prey ModelsPrey isoclines have characteristic hump shape (cont.)Below the isocline, prey populations increasePredator isoclinesThreshold density, where predator population will increasePredator population can in
65、crease to carrying capacity102Chapt. 10Predator-Prey ModelsPredator isoclines (cont.)Mutual interference or competition between predatorsMore prey required for a given density predatorPredator isoclines slopes toward the rightSuperimpose prey and predator isoclinesFigure 10.5103Chapt. 10Predator-Pre
66、y ModelsSuperimpose prey and predator isoclines (cont.)One stable point emerges: the intersection of the linesThree general casesInefficient predators require high densities of prey (Figure 10.5a)104Chapt. 10Damped oscillationsPreyisoclinePredatorisoclinea)105Chapt. 10Predator-Prey ModelsThree gener
67、al cases (cont.)A moderately efficient predator leads to stable oscillations of predator and prey populations (Figure 10.5b)106Chapt. 10Stable oscillationsPopulation densityPredator equilibrium densityb)107Chapt. 10Predator-Prey ModelsThree general cases (cont.)A highly efficient predator can exploi
68、t a prey nearly down to its limiting rareness (Figure 10.5c)108Chapt. 10Increasing oscillationsPredator densityc)109Chapt. 10Predator-Prey ModelsAll based on how efficient predator isShift in isoclinesPrey starvation (shift to left)Food enrichment (shift to right) (Figure 10.5d)110Chapt. 10K1increas
69、es to K1* with enrichmentPreyPredatorPredator isocline remains unchanged“The paradox of enrichment”Prey isoclinechangesK1K1*d)111Chapt. 10Predator-Prey ModelsFood enrichment (shift to right) (cont.)Carrying capacity changesPredator isocline changes “paradox enrichment” : Increases in nutrients or fo
70、od destabilizes the system112Chapt. 10Predator-Prey ModelsFunctional responseHow an individual predator responds to prey density can affect how predators interact with prey (Figure 10.6)113Chapt. 10IIIIIINumber of prey eaten per predatorPrey density114Chapt. 10Predator-Prey ModelsFunctional response
71、 (cont.)Three typesType I: Individuals consume more prey as prey density increasesType II: Predators can become satiated and stop feeding, or limited by handling time.115Chapt. 10Predator-Prey ModelsThree types (cont.)Type III: Feeding rate is similar to logistic curve; low at low prey densities, bu
72、t increases quickly at high densitiesChanges in prey consumptionFunctional response changes (Figure 10.7)116Chapt. 10Predator-Prey ModelsFunctional response changes (cont.)Dictates how individual predators respond to prey populationNumerical response changesGoverns how a predator population migrates
73、 into and out of areas in response to prey densities117Chapt. 10Field Studies of Predator-Prey InteractionsField comparisons to modelsDo predators control prey populations?Importance of predators in controlling prey densityKaibab deer herdKaibab Plateau (Northern Arizona)118Chapt. 10Field Studies of
74、 Predator-Prey InteractionsKaibab deer herd (cont.)Declared a national park around 1900All big predators were removed and deer hunting was prohibitedEstimates of 10 fold increase in deer populationReevaluated by Graham Caughley (1970)119Chapt. 10Field Studies of Predator-Prey InteractionsReevaluated
75、 by Graham Caughley (1970) (cont.)Predator control had some impact; cessation of hunting and removal of competing sheep and cattle also had an impactSerengeti plains of eastern AfricaLarge predators have little effect on large mammal prey120Chapt. 10Field Studies of Predator-Prey InteractionsSerenge
76、ti plains of eastern Africa (cont.)Most prey taken are either injured or senileContribute little to future generationsPrey are migratoryMoose population on Michigans Isle Royale121Chapt. 10Field Studies of Predator-Prey InteractionsMoose population on Michigans Isle Royale (cont.)Wolf-free existence
77、 until 1949.Durwood Allen (1958) began to track wolf and moose populationsTrends in populations (Figure 10.8)122Chapt. 106001020304050Wolves195519601965197019751980198519901995 1997MooseWolvesYear200400600800100012001400160018002000220024002600Moose0123Chapt. 10Field Studies of Predator-Prey Interac
78、tionsTrends in populations (cont.)Wolf populationPeaked at 50 in 1980Severe nosedive in 1981Small recovery in the late 1990sMoose populationIncreased steadily in the 1960s and 1970sDeclined as the wolf population increased until 1981124Chapt. 10Field Studies of Predator-Prey InteractionsMoose popula
79、tion (cont.)A record population of 2500 was reached in 1995, when the wolf population was lowGood evidence of prey population control by predatorsConfounded in 1996 when the moose population crashed - starvation125Chapt. 10Field Studies of Predator-Prey InteractionsCanada lynx and snowshoe harePopul
80、ations show dramatic cyclic oscillations every 9 to 11 years (Figure 10.9)126Chapt. 102040608010012020406080100120140160180200Abundance of lynxAbundance of haresAbundance of lynx (x 1000)Abundance of hares (x 1000)1850186018701880189019001910192019301940127Chapt. 10Field Studies of Predator-Prey Int
81、eractionsCanada lynx and snowshoe hare (cont.)Cycle has existed as long as records have existed (over 200 years)An example of intrinsically stable predator-prey relationship128Chapt. 10Introduced PredatorsMethod for determining the effects of predatorsDingo predations on kangaroos in AustraliaDingoI
82、ntroduced speciesLargest Australian carnivore129Chapt. 10Introduced PredatorsDingo (cont.)Predator of imported sheepEliminated from certain areasSpectacular increases in native species160 fold increase in red kangaroosOver 20 fold increase in emus130Chapt. 10Introduced PredatorsDingo (cont.)Effects
83、on feral pigsShortage of young pigsConsiderable impact on recruitment of pigs (Figure 10.10)131Chapt. 100604020204060Age class (years)Males (%)Females (%)0604020204060Males (%)Females (%)6+5-64-53-42-31-20.5-1.056+5-64-53-42-31-20.5-1.05Age class (years)(a) Dingoes present(a) Dingoes present132Chapt
84、. 10Introduced PredatorsEuropean foxes and feral cats in AustraliaDamage domestic livestockEffects when removed (Figure 10.11)133Chapt. 100204060Predators shotNo shooting19811982Mean no. of rabbits per km of transect134Chapt. 10Introduced PredatorsLamprey and the Great LakesConstruction of Wetland C
85、anal allowed lamprey to enter the Great LakesDramatic reduction in lake trout (Figure 10.12)135Chapt. 10Lake HuronMean production765432107654321076543210Lake MichiganLake SuperiorMean productionMean production1930 1935 1940 1945 1950 1955 1960Lake trout production (millions per pound)136Chapt. 10Int
86、roduced PredatorsLamprey and the Great Lakes (cont.)Trout recovered after lamprey population was reduced137Chapt. 10Field Experiments with Natural SystemsLions in South AfricaKruger National Park, 1903Lions ShotNumber of large prey increasedShooting of lions ends, 1960Wildebeast increase so much tha
87、t their numbers had to be culled from 1965 to 1972138Chapt. 10Field Experiments with Natural SystemsGray partridge, European game birdFigure 10.13139Chapt. 10Field Experiments with Natural SystemsGray partridge, European game bird (cont.)Over 20 million shot in Great Britain in the 1930sOnly 3.8 mil
88、lion shot in the mid-1980sHigh chick mortality due to starvation140Chapt. 10Field Experiments with Natural SystemsOnly 3.8 million shot in the mid-1980s (cont.)Reduced insects due to introduction of herbicides in the 1950s was suspectedHowever, smaller populations in areas where there was no control
89、 of predators by gamekeepers141Chapt. 10Field Experiments with Natural SystemsOnly 3.8 million shot in the mid-1980s (cont.)Predation control increasedThe number of partridges that bred successfullyThe average size of the broodsPartridge populations by 75 %142Chapt. 10Field Experiments with Natural
90、SystemsPredators and rodents in FinlandLarge scale removal of predators, April 1992 and 1995 over 2-3 km2Large increase in rodent population by June (compared to control plots) (Figure 10.14)143Chapt. 10AprilJuneAprilJune3.532.521.510.503.532.521.510.50Without predatorsWith predatorsMean number of r
91、odents per sampleMean number of rodents per sample144Chapt. 10Applied EcologyHumans as predators - whalingExploitation necessaryIs harvesting at any level sustainable?History of Antarctic whalingFigure 1145Chapt. 10Applied EcologyHistory of Antarctic whaling (cont.)1930s, blue whales primarily harve
92、sted1950s, blue whale population depleted, replaced with fin whale1960s, fin whale population collapsed146Chapt. 10Applied EcologyHistory of Antarctic whaling (cont.)1960s, humpback whale population collapsedPrior to 1958, Sei whales hardly ever harvestedReduction in other whales made Sei whale attr
93、active147Chapt. 10Applied EcologyPrior to 1958, Sei whales hardly ever harvested (cont.)Peak harvest of about 20,000 by 1964-65Catches declined thereafter due to limitationsThe relatively small minke whaleWas ignored in the southern oceans until 1971-72148Chapt. 10Applied EcologyThe relatively small
94、 minke whale (cont.)Began to be taken, and is now the largest component of the southern baleen whale catchWhale ban proposed in 1985-86, took effect in 1988149Chapt. 10Applied EcologyIceland, Norway, and Japan, 1994Argued for resumption of limited commercial whalingShould we ban commercial whaling?W
95、hale populations are recovering150Chapt. 10Applied EcologyWhale populations are recovering (cont.)Ex. Blue whale populations have increased four foldEx. California grey whales have recovered to prewhaling levels151Chapt. 10SummaryPredation is a strong selective force in natureAposematic colorationCa
96、mouflageBatesian and Mullerian mimicryIntimidation displaysPolymorphisms152Chapt. 10SummaryPredation is a strong selective force in nature (cont.)Chemical defensesModeling predator-prey interactionsEven simple predator-prey models show153Chapt. 10SummaryEven simple predator-prey models show (cont.)S
97、table cyclesWildly increasing and unstable oscillationsDifficulty in predicting or modeling how predators and prey interactMutual interference between predators154Chapt. 10SummaryDifficulty in predicting or modeling how predators and prey interact (cont.)Existence of specific predator territory size
98、sAbility of predators to feed on more than one type of prey155Chapt. 10SummaryLarge-scale observations supportPredators only take weak and sickly individualsPrey populations influence predator numbers, not vice versa156Chapt. 10SummaryAccidental or deliberate introductions of exotic predatorsProfoun
99、d effects on native prey populationsPredators have important regulatory effects on prey157Chapt. 10SummaryAccidental or deliberate introductions of exotic predators (cont.)May not be indicative of “natural systems”158Chapt. 10SummaryEvidence from natural systemsMost studies have concluded that preda
100、tors have a significant effect on prey159Chapt. 10Discussion Question #1Should ranchers be concerned about the reintroduction into their vicinity of large predators, like wolves and panthers?160Chapt. 10Discussion Question #2Do sea lions, otters, or dolphins decrease the stock of fish available for
101、people that fish?161Chapt. 10Discussion Question #3Would the number of deer available for hunters be the same in the presence of large predators?162Chapt. 10Discussion Question #4What data would you need to collect to answer the above 3 questions?163Chapt. 10Discussion Question #5What can the effect
102、s of exotic predators tell us about the strength of predation? What cant they tell us?164Chapt. 10Discussion Question #6Which do you think more likely: that predators control prey populations or that prey control predator populations? Would the answer vary according to the particular system? Give an
103、 example.165Chapt. 10Discussion Question #7What shortcomings do you think Rosenzweig and MacArthurs predator and prey isoclines have? What would these shortcomings mean in terms of determining how predators and prey interact?166Chapt. 10Discussion Question #8A great many fish stocks seem to have been overfished. How do you think we could prevent overfishing? What biological information do we need to have, and how can we get it when we cant see the population in question?167Chapt. 10
