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Predator vs prey1/3/2023 ![]() ![]() Grouse cycling direct response to predation pressure. Decline of the lynx abated somewhat by ability to shift to grouse as alternative prey. Predators decline as a result of prey decline. Hare-plant interaction leads to decline in hare population – decline in hare population not a result of predator effects. Plant response is to produce toxins which remains unpalatable for 2-3 years. Starvation due to low availability of foodĬoncomitant with increase, increase in grazing. Researchers noted that decline of hare was characterized by: Over 8-11 years period the abundance of hare changes 10 – 30 fold (up to 100x in favorable habitat which occurs over wide geographic range – Alaska to Newfoundland. Hare feeds on twigs of numerous shrubs and small trees. (Left: abundance lynx Right: abundance of hares)Ĭycle has about 8-11 yrs periodicity. Since 1920’s ecologists looked at cycling in hare and lynx which was recognized by traders 100 years prior. With predation on predator (largemouth bass on bluegill) Predator bluegill restricted to vegetated areas.Ĭlassic case of coupled oscillation involves predator and prey interaction between snowshoe hare and Canadian lynx. ![]() Without predation on either predator or prey both range over entire habitat 4: When largemouth bass (which prey on small bluegill sunfish are present, many sunfish take prey form vegetation habitat where they are relatively protected from predation. 4: Bluegill (predator) vs invertebrate prey.įig. Size and spatial escapes – barnacles (prey) vs snail (predator)įig. Predators disperse, prey re-establish by migration of larvae. 3: Example for 2) dispersal and immigration (Left: Prey population Right: Predator Population)įig. 2: Huffaker’s 1958 "hide and seek" experiment with mite and mite predator. Coexistence possible when, in addition to heterogeneity, temporary barriers to predator migration are established.įig.With predatory mite added both prey and predator go extinct, despite heterogenous habitat.In the absence of predators, the herbivorous mite population flucuates through time but persists.Huffaker’s 1958 "hide and seek" experiment with mite and mite predator. Without a refuge, but with periodic immigration, predator and prey can coexist With a refuge for the prey, the predator goes extinct Without refuge in closed system ® prey go extinct, obviously not evolved under these conditions – natural systems are "open" Size escapes (either young are too small or adults too large for predators to consume).Įxamples: Refuge for prey - Gause’s experiments using protozoan, Paramecium (prey) and Didinium (predator).Predator/Prey interactions continued (factors leading to coexistence) Lecture 16: Predator/Prey Cycles – Community Ecology ![]()
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