Chap.10 Predation

Chap.10 Predation

鄭先祐鄭先祐

生態主張者生態主張者 AyoAyo 工作室工作室

Ecology 2001 Chap.10 Predation 2

Fig. 10.1 Predation takes many forms (a) A double crested cormorant actively seeks and chases its fish prey.


Fig. 10.1 Predation takes many forms (b) A little blue heron waits motionless to ambush its prey. (fish)


Fig. 10.1 Predation takes many forms (c) A minke whale feeds on vast numbers of small crustaceans in the Antarctic ocean.


Fig. 10.1 Predation takes many forms (d) A pitcher plant in a bog traps insects in its highly modified leaves.


Fig. 10.1 Predation takes many forms (e) Insect larvae graze on the stems and leaves of fireweeds..


Fig. 10.1 Predation takes many forms (f) A moose feeds in the same patch of fireweed..


Predation

Carnivorous predationCarnivorous predation Herbivorous predationHerbivorous predation Optimal Foraging theoryOptimal Foraging theory Community-level effects of predationCommunity-level effects of predation Environmental application: Biological Environmental application: Biological

control of pests: Putting predators to workcontrol of pests: Putting predators to work


Carnivorous predation

Predator adaptationsPredator adaptations Prey detection and recognitionPrey detection and recognition Tactics for capturing preyTactics for capturing prey

Prey adaptationsPrey adaptations Avoiding detectionAvoiding detection Avoiding captureAvoiding capture Disrupting predator handlingDisrupting predator handling


Prey detection and Recognition

Resolving power of a bald eagle’s eye is Resolving power of a bald eagle’s eye is approximately that of a pair of 7 x approximately that of a pair of 7 x binoculars.binoculars.

Smell (chemoreception)Smell (chemoreception) Sound (Fig. 10.2 owls)Sound (Fig. 10.2 owls) Electric fields to detect preyElectric fields to detect prey


Fig. 10.2 The circles around the eyes of many species of owls are parabolic reflectors that help gather sound and channel it to the ears.


Fig. 10.3 pulses(solid lines) emitted by a bat and echoes(dashed lines) received by the bat as it approaches and object.


Tactics for capturing prey

分類：分類： Ambush its prey or actively seeks themAmbush its prey or actively seeks them Hunts singly or in groupsHunts singly or in groups


Fig. 10.4 Foraging success of captive black-headed gulls in flocks of different sizes.


Prey adaptations Avoiding detectionAvoiding detection

Fig. 10.5 a white-tailed ptarmigan.


Fig. 10.5b. The American bitten are examples of cryptic coloration.


隱藏的方法 Its color matches the background.Its color matches the background. Its shape is asymmetrical.Its shape is asymmetrical. It is counter-shaded (the lower part of the It is counter-shaded (the lower part of the

body is light and upper part is dark)body is light and upper part is dark) Its outline blend into the background.Its outline blend into the background. Its eyes are hidden.Its eyes are hidden. It remains motionless. It remains motionless.


Avoiding capture

Antelope Antelope 快跑。快跑。警告聲音。警告聲音。停止不動。停止不動。 Provide False targetsProvide False targets Some marine invertebrates use flashes of biSome marine invertebrates use flashes of bi

oluminescence to startle predators.oluminescence to startle predators. Safety in numbers strategy.Safety in numbers strategy.


Fig. 10.6 increase in musk ox group size as a function of wolf density in winter and summer.


Fig. 10.7 Relative amount of the average total risk of predation incurred by Atlantic siversides in six positions within a school under attack by launchers and passers.F= front; B= back; O= outside; TM = true middle; CM= confused middle; AA = after attack.


Predator swamping

Fig. 10.8 The relationship between average effective brood size at fledging and hatch date in snow geese.


Disrupting predator handling

The development of significant defensive wThe development of significant defensive weapons such as antlers, horns, shells, and cheapons such as antlers, horns, shells, and chemical deterrents.emical deterrents.

In the newt, Taricha torosa, a potent neurotoIn the newt, Taricha torosa, a potent neurotoxin called tetrodotoxin acts as a chemical dexin called tetrodotoxin acts as a chemical deterrent to predation.terrent to predation.


Herbivorous predation

1. 1. 植物的生產力和營養成分，隨著季節而有所不同。植物的生產力和營養成分，隨著季節而有所不同。掠食者必要把握機會，配合掠食者必要把握機會，配合 green wavegreen wave 。。

2. 2. 植物有植物有 anti-grazing strategyanti-grazing strategy 。。 Koala Koala 專食專食 eucalyptus treeseucalyptus trees 的樹葉。的樹葉。 EucalyptusEucalyptus

樹葉，營養低，且含有樹葉，營養低，且含有 lignin lignin 和和 tannintannin ，降低消，降低消化。化。 KoalaKoala 的代謝率低，直腸很長，食物留在腸的代謝率低，直腸很長，食物留在腸子的時間很長子的時間很長 (8(8 天天 )) 。。

Monarch Monarch 蝴蝶的幼蟲，吃食含有毒素的葉子，這蝴蝶的幼蟲，吃食含有毒素的葉子，這使使 MonarchMonarch 蝴蝶的成蟲體內含有毒素。蝴蝶的成蟲體內含有毒素。

Squash Squash 甲蟲使用行為的方法避開植物的化學防衛。甲蟲使用行為的方法避開植物的化學防衛。先剪斷葉片的主要葉脈，是其無法傳導入化學物先剪斷葉片的主要葉脈，是其無法傳導入化學物質，然後再吃葉片。質，然後再吃葉片。


Two fundamental groups

Stealthy herbivores and Opportunistic herbiStealthy herbivores and Opportunistic herbivores vores

Stealthy herbivoresStealthy herbivores ：專精的覓食方式：專精的覓食方式 Opportunistic herbivoresOpportunistic herbivores ：大量多樣覓食：大量多樣覓食

的方式。的方式。


Plant adaptations to herbivores

Structural and chemical adaptationsStructural and chemical adaptations Two hypotheses of the origin of Secondary Two hypotheses of the origin of Secondary

compounds.compounds.1.1. Secondary compounds, produced as by-Secondary compounds, produced as by-

products of plant metabolism and co-opted for products of plant metabolism and co-opted for defense because of their toxic nature.defense because of their toxic nature.

2.2. These compounds are evolved These compounds are evolved de novode novo in in response to grazing as a selection pressure. response to grazing as a selection pressure. The energetic cost to the plant is high.The energetic cost to the plant is high.


圖 10.9 Lotus corniculatus可產生氰酸的植物體比率。比較溫暖的地區，比率較高。這與掠食壓力相關。


範例：抗掠食的抗掠食的 Secondary compounds Secondary compounds 不僅發現在被不僅發現在被

子植物和裸子植物，而且也發生在低等植物。子植物和裸子植物，而且也發生在低等植物。譬如：譬如： cyano-bacteria (cyano-bacteria ( 藍綠藻藍綠藻 )) ，珊瑚礁的藻，珊瑚礁的藻

類，海草類，海草 (Fig. 10-10)(Fig. 10-10) 。。當有掠食壓力時，當有掠食壓力時， Brown alga(Disyota manstruaBrown alga(Disyota manstrua

lis)lis) 會產生高濃度的會產生高濃度的 diterpenoid dictyolsditerpenoid dictyols 。而其。而其旁邊的同種個體，若沒有掠食壓力，則不會產旁邊的同種個體，若沒有掠食壓力，則不會產生。生。

有蟲吃的有蟲吃的 BirchBirch ，隔年的樹葉，於其樹葉上吃，隔年的樹葉，於其樹葉上吃食的蟲子營養都不良。原因是食的蟲子營養都不良。原因是 Birch Birch 產生產生 defendefense chemistry.se chemistry.


圖 10.10 海草產生的六種代謝物質，對掠食者的影響力。


Allocation of resources to defense in Plants1.1. Availability of plants to herbivores.Availability of plants to herbivores.

2.2. Plant architecturePlant architecture

3.3. Seasonal scarcity Seasonal scarcity

4.4. Involvement of specialized herbivoresInvolvement of specialized herbivores


The effects of herbivores

Consumption of plant parts is known to Consumption of plant parts is known to have negative effects.have negative effects.

However, some evidence suggests that the However, some evidence suggests that the activity of herbivores has beneficial effects.activity of herbivores has beneficial effects. Grazing increases seed production, Grazing increases seed production,

increases biomass production, increases increases biomass production, increases nutrient content. nutrient content.


範例： Scarlet gilia

Grazing pressure by mule deer and elk was intense Grazing pressure by mule deer and elk was intense on their Arizona study sites.on their Arizona study sites.

The grazers fed on nearly 75% of all plants and reThe grazers fed on nearly 75% of all plants and removed as much as 95% of the above ground biommoved as much as 95% of the above ground biomass.ass.

When a single stalk was eaten, however, it was repWhen a single stalk was eaten, however, it was replaced with four new stalks.laced with four new stalks.

被掠食的植物體比沒有被掠食的植物體，可產被掠食的植物體比沒有被掠食的植物體，可產生高達生高達 3.053.05 倍的種仔。其倍的種仔。其 fitness fitness 比是比是 2.4 : 12.4 : 1 。。


圖 10.12 Fruit production in matched pairs of plants of Scarlet gilia.


Optimal foraging theory

Energy maximizersEnergy maximizers Time maximizersTime maximizers

Fundamental assumptions of the theory are:Fundamental assumptions of the theory are:

1.1. Foraging behavior has a genetic basisForaging behavior has a genetic basis

2.2. Fitness is related to the net energy intake.Fitness is related to the net energy intake.


Optimal diet

E/h , where E is the energy in the diet anE/h , where E is the energy in the diet and h is the handling time (or energy) required d h is the handling time (or energy) required to capture, subdue, and consume the diet.to capture, subdue, and consume the diet.

E / (s + h), where s is the search time.E / (s + h), where s is the search time. EEii/h/hii >= E / (s + h) >= E / (s + h) ii 食物的能量價值必要高於目前的平均價食物的能量價值必要高於目前的平均價

值，掠食者才有可能轉而向值，掠食者才有可能轉而向 ii 食物。食物。


Optimal use of food patches

掠食者停留於同一個覓食區的時間長短，掠食者停留於同一個覓食區的時間長短，這與移動到另一個覓食區所需要花的時這與移動到另一個覓食區所需要花的時間間 (travel time)(travel time) 長短有關。長短有關。

Fig. 10.13 Optimal patch theory.Fig. 10.13 Optimal patch theory.


圖 10.13 The curve depicts the cumulative amount of energy gained as a function of the amount of time a predator stays in a patch.

T1 較小，離開的時間較快。

T2 較長，離開的時間會較慢。


Biological control of pests: putting predators to work Pests and weeds cause tremendous damage to botPests and weeds cause tremendous damage to bot

h natural and agricultural habitats.h natural and agricultural habitats. Some of these pests are exotic species, accidentalSome of these pests are exotic species, accidental

ly or intentionally introduced to regions beyond tly or intentionally introduced to regions beyond their natural range.heir natural range.

若是使用殺蟲劑，至少有兩個問題：若是使用殺蟲劑，至少有兩個問題： 1. The targets of the chemicals develop resista1. The targets of the chemicals develop resista

nce. (nce. ( 抗藥性抗藥性 )) 2. These toxins may themselves pose serious 2. These toxins may themselves pose serious

environmental problems.environmental problems. 因此有所謂的因此有所謂的 biological control biological control

Environmental application


Fig. 10B.1 A classic type of biological control in which the average abundance of an insect pest is reduced after the introduction of a predator.


Integrated pest management IPM, a program of carefully selected control IPM, a program of carefully selected control

techniques tailored to address each particular techniques tailored to address each particular insect pest problem.insect pest problem.

Insect numbers are monitored carefully and Insect numbers are monitored carefully and population models are used to predict irruptions of population models are used to predict irruptions of the pest.the pest.

Insecticides are used only sparingly and locally in Insecticides are used only sparingly and locally in response to this information.response to this information.

Natural predators or parasites are released widely Natural predators or parasites are released widely in areas of local infestation.in areas of local infestation.

Sterilization procedures or sex pheromones may Sterilization procedures or sex pheromones may be used.be used.


範例：運用 IPM 控制 gypsy moth 意外的被引進意外的被引進 Massachusetts in 1869.Massachusetts in 1869. The population exploded across the northeaThe population exploded across the northea

stern US, defoliating many hectares of foresstern US, defoliating many hectares of forest.t.

IPM IPM 包含：包含： pesticides, two species of parapesticides, two species of parasitic flies and sex pheromones.sitic flies and sex pheromones.


Fig. 10B.2 The rapid increase in the distribution of the gypsy moth after its introduction to North America.


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Chap.10 Predation

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