【正文】 160 fold increase in red kangaroos 187。Declined as the wolf population increased until 1981 Field Studies of PredatorPrey Interactions – Moose population (cont.) 187。Peaked at 50 in 1980 187。 low at low prey densities, but increases quickly at high densities – Changes in prey consumption ? Functional response changes (Figure ) PredatorPrey Models ? Functional response changes (cont.) – Dictates how individual predators respond to prey population ? Numerical response changes – Governs how a predator population migrates into and out of areas in response to prey densities Field Studies of PredatorPrey Interactions ? Field parisons to models ? Do predators control prey populations? ? Importance of predators in controlling prey density – Kaibab deer herd ? Kaibab Plateau (Northern Arizona) Field Studies of PredatorPrey Interactions – Kaibab deer herd (cont.) ? Declared a national park around 1900 ? All big predators were removed and deer hunting was prohibited ? Estimates of 10 fold increase in deer population ? Reevaluated by Graham Caughley (1970) Field Studies of PredatorPrey Interactions ? Reevaluated by Graham Caughley (1970) (cont.) – Predator control had some impact。s predator and prey isoclines have? What would these shortings mean in terms of determining how predators and prey interact? Discussion Question 8 ? A 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 can39。Confounded in 1996 when the moose population crashed starvation Field Studies of PredatorPrey Interactions – Canada lynx and snowshoe hare ? Populations show dramatic cyclic oscillations every 9 to 11 years (Figure ) 20 40 60 80 100 120 20 40 60 80 100 120 140 160 180 200 Abundance of lynx Abundance of hares Abundance of lynx (x 1000) Abundance of hares (x 1000) 1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 Field Studies of PredatorPrey Interactions – Canada lynx and snowshoe hare (cont.) ? Cycle has existed as long as records have existed (over 200 years) ? An example of intrinsically stable predatorprey relationship Introduced Predators ? Method for determining the effects of predators ? Dingo predations on kangaroos in Australia – Dingo ? Introduced species ? Largest Australian carnivore Introduced Predators – Dingo (cont.) ? Predator of imported sheep ? Eliminated from certain areas – Spectacular increases in native species 187。Increased steadily in the 1960s and 1970s 187。s Isle Royale (cont.) ? Wolffree existence until 1949. ? Durwood Allen (1958) began to track wolf and moose populations ? Trends in populations (Figure ) 60 0 10 20 30 40 50 Wolves 1955 1960 1965 1970 1975 1980 1985 1990 1995 1997 Moose Wolves Year 200 400 600 800 1000 1200 1400 1600 1800 2020 2200 2400 2600 Moose 0 Field Studies of PredatorPrey Interactions ? Trends in populations (cont.) – Wolf population 187。Predator isocline changes – “paradox enrichment” : Increases in nutrients or food destabilizes the system PredatorPrey Models ? Functional response – How an individual predator responds to prey density can affect how predators interact with prey (Figure ) I II III Number of prey eaten per predator Prey density PredatorPrey Models ? Functional response (cont.) – Three types ? Type I: Individuals consume more prey as prey density increases ? Type II: Predators can bee satiated and stop feeding, or limited by handling time. PredatorPrey Models – Three types (cont.) ? Type III: Feeding rate is similar to logistic curve。Reinforce basic distasteful design 187。 .競(jìng)爭(zhēng) .掠食、寄生 .遺傳反饋機(jī)制 (抗病種的培育 ) 澳洲野兔 ? 粘液病毒 ? 抗病種 Density independent factor .氣候因素 .土壤因素 .營(yíng)養(yǎng) .理化 .空間 .汙染 Extrinsic factors: External factors acting on populations . Predation, parasitism . Competition for food ? density depended . Competition for space ? density depended . Random stochastic change ? density independent . Weather 種群是一個(gè)具有自我調(diào)節(jié) (self regulation)機(jī)制的生活系統(tǒng)，可以按照自身的性質(zhì)及環(huán)境狀況調(diào)節(jié)它們的數(shù)量。Chapter 10 Predation 169。 ＊植物的自疏現(xiàn)象 ＊禾本科植物的分的產(chǎn)生和生長(zhǎng) ＊遺傳特性 (抗逆性 ) ＊內(nèi)分泌調(diào)節(jié) (旅鼠 ) Crowding stress 腎上腺髓質(zhì) (adrenocorticotropin) 腦下腺 (Epinephrine) 腎上腺皮質(zhì) (Corticoids) 危急反應(yīng) Alarm response Introduction ? Wolves in Yellowstone Park (Figure ) – . Fish and Wildlife Service, 1980’s – Reintroduce in Yellowstone Park and stabilize wolf populations in Minnesota and Montana – Concerns ? Cattle ranchers concerned: Decimate herd? ? Are predators tied to the health of the main prey? ? Can predators switch prey? ? Ramifications to reestablishment – Results: No major effects Introduction ? Predation – Traditional view: carnivory – Differences from herbivory ? Herbivory is nonlethal – Differences from parasitism ? In parasitism, one individual is utilized for the development of more than one parasite Introduction ? Predation (cont.) – Predatorprey associations ? Figure Intimacy Low High Parasite Parasitoids Grazer Predator Lethality High Low Antipredator Adaptations ? Aposematic or warning coloration – Advertises an unpalatable taste – Ex. Blue jays and monarch butterflies ? Caterpillar obtains poison from milkweed Antipredator Adaptations – Ex. Blue jays and monarch butterflies (cont.) ? Blue jays suffer violent vomiting from ingesting caterpillar – Ex. Tropical frogs ? Toxic skin poisons ? Figure Antipredator Adaptations ? Camouflage – Blending of anism in