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Gause experiments

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1st to study Lotka-Volterra competition model. He examined competition between two species of Paramecium, Paramecium aurelia and Paramecium caudatum. P. aurelia has higher rate of population growth than P. caudatum and can tolerate a higher population density. His experiment was he used a mixed culture, P. aurelia outcompetes P. caudate and result is competitive exclusion. In another experiment he used P. caudate and P. bursaria where the two species coexisted bc P. caudate fed on bacteria suspended in solution and P. bursaria confined its feeding to bacteria at the bottom of the tube

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Park experiments

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Conducted several competition experiments with lab populations of flour beetles. Outcome of competition between Tribolium castaneum and Tribolium confusum depended on environment temperature, humidity, and fluctuations in the total number of eggs, larvae, pupae, and adults. Often, outcome of competition was not determined until many generations had passed

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Tilman experiments

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Grew lab populations of 2 species of diatoms, Asterionella formosa and Synedra ulna. Both species require silica for formation of cell walls. Researchers monitored population growth and decline as well as the level of silica in the water. When grown alone, both species kept silica at a low level because they used it to form cell walls When grown together, use of silica by S. ulna reduced concentration to level below that necessary for A. formosa to survive and reproduce. By reducing resource availability, S. ulna drove A. formosa to extinction.

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Competitive exclusion principle

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hypothesis that when 2 or more species coexist using the same resource, one must displace or exclude the other ("complete competitors" cannot coexist)

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Competitive release

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niche expansion in response to reduced interspecific competition

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resource partitioning

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Many species that share the same habitat coexist by partitioning available resources, when each species exploits a portion of the resources unavailable to others, competition is reduced. often viewed as the product of coevolution of characteristics that function to reduce competition

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niche differentiation

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fundamental niche is the ecological niche in the absence of interactions with other species realized niche is the portion of the fundamental nice that a species actually exploits as a result of interactions with other species

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character displacement

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principle that 2 species are more different where they occur together than where they are separated geographically

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allelopathy

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in plants, in which chemicals produced by some plants inhibit germination and establishment of other species

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coyotes and wolves

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decline of gray wolf populations throughout much of North America have been paroled by dramatic expansion in range of coyotes evidence from areas in which wolves have been reintroduced suggests that the expansion of coyotes was in part of a result of competitive release from wolf populations over past century

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true predator

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kill their prey more or less immediately upon capture

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aggregative response

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movement predators into areas of high prey density

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prey switching

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changing the diet from less abundant to a more abundant prey species

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predation

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relationship in which one living organism serves as a food source for another

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optimal foraging theory

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tendency of animals to harvest food efficiently, selecting food sizes or food patches that supply maximum food intake for energy expended

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coevolution

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joint evolution of 2 or more non interbreeding species that have a close ecological relationship; through reciprocal selective pressures, the evolution of one species in the relationship is partially dependent on evolution of other

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predator defenses

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evolved characteristics that help prey avoid detection or capture

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chemical defense

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use by organisms off bitter distasteful or toxic secretions that deter potential enemies

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object resemblance

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prey species assumes appearance of some feature in environment such as a lead to avoid detection

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cryptic coloration

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coloration of organisms that makes them resemble or blend into their habitat or background

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flashing coloration

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hidden markings on animals that when quickly exposed startle or divert attention of potential predator

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Bayesian mimicry

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mimicry occurs when an animals without any special defense mechanism mimics coloration of animal that does possess a defense

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aposematism

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(warning coloration) conspicuous color or markings on an animal that serve to discourage potential predators

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mullein mimicry

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mimicry occurs when several animals with special defense mechanism share same coloration

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behavioral defenses

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aggressive and submissive postures or actions that threaten or deter enemies

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protective armor

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hard outer covering of an animal body such as shell of turtles and spines of porcupines that deters or makes the owner somewhat invulnerable to most enemies

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predator satiation

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predator defense mechanism involving physiological timing of reproduction by a prey species, plant or animal, to produce a maximum number of sees or young within a short period more than predators can possibly consume thus allowing a greater percentage of offspring to escape

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constitutive defense

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fixed feature of an organism such as object resemblance that deters predators

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induced defense

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defense response brought about or induced by presence or action of predator; for example alarm pheromones

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ambush

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hunting by lying in wait for prey to come along typical of frogs, alligators, crocodiles, lizards, and certain insects

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stalking

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typical of herons and cats deliberate form of hunting with a quick attack predator search time may be great but pursuit time is minimal spend more time and energy encountering prey

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pursuit

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typical of many hawks, lions, wolves, and insectivorous bats involves minimal search time bc predator usually knows location of prey but pursuit time is great more time capturing and handling prey

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herbivory

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form of predation in which animals prey on autotrophs (plants and algae)

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secondary compound

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chemicals that are not involved in basic metabolism of plant cells

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quantitive inhibitor

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secondary compounds that are produced by plant in large quantities

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qualitative inhibitor

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secondary compounds that function as defense against herbivory that are present in small to minute quantities

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snowshoe hare lynx horned owl interaction

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interaction between predators and food supply produces hare cycle and in turn hare cycle affects population dynamics of its predators

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maximum sustainable yield

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maximum rate at which individuals can be harvested from a population without reducing its size; recruitment balances harvesting

Ecology Quiz 6 (Ch 13 &14) – Flashcards

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