Chapter 54: Community Ecology Flashcards Preview

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Flashcards in Chapter 54: Community Ecology Deck (65):
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community

group of populations of different species living close enough to interact

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interspecific interactions

competition, predation, herbivory, symbiosis, facilitation

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competition

-/- interaction involving individuals of different species competing for a resource that limits their growth and survival

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competitive exclusion

two species cannot coexist in the same place permanently if they compete for the same resources

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ecological niche

summary of a species' use of biotic and abiotic resources

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resource partitioning

differentiation of niches that enables similar species to coexist in a community (indicates past competition and evolution of niches)

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fundamental niche often differs from

actual niche

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character displacement

tendency for characteristics to diverge more in geographically overlapping populations than in geographically separate populations

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geographically overlapping

sympatric

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geographically separate

alopatric

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predation

+/- interaction in which predator kills and eats prey

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cryptic coloration

camouflage makes it difficult to see prey

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aposematic coloration

bright warning coloration

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disruptive coloration

makes outline of prey harder to see (stripes on a zebra)

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batesian mimicry

harmless species imitate a harmful species

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mullerian mimicry

two or more harmful species imitate each other

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herbivory

+/- interaction in which organism eats parts of a plant or alga

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types of symbiosis

parisitism, mutualism, commensalism

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parasitism

+/- interaction in which parasite derives nutrients from the host

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endoparasites

parasites that live inside body

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ectoparasites

parasites that live on the external surface of the body

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mutualism

+/+ interaction in which both species benefit

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obligate mutualism

two species cannot survive without each other

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facultative mutualism

two species can survive on their own

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commensalism

+/0 interaction in which one species benefits and the other is unaffected

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facilitation

+/+ or +/0 interaction without living intimately as in symbiosis

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example of facilitation

trees shade ground and make soil more hospitable for salt marsh plants

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species diversity

variety of organisms that make up a community

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species richness

# of different species

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relative abundance

proportion each represents of all individuals in the community

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Shannon diversity

H= -(plnp + plnp + ...) p=relative abundance
higher H means more diversity

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more diverse communities tend to have

higher productivity and more stability

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trophic structure

feeding relationships between organisms

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food chain

transfer of energy from primary producer to consumers to decomposers

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food webs

food chains linked together

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energetic hypothesis

length of food chain is limited by inefficiency of food transfer (10%)

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biomass

total mass of all individuals in a population

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dynamic stability hypothesis

long food chains are less stable than short food chains
population disturbances at lower levels may cause local extinction of top level carnivores

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dominant species

species that are most abundant/have highest biomass

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keystone species

not usually abundant in a community but has control due to specific niche/role

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ecosystem engineers

species that dramatically alter their environment

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what do V, H, and arrows mean

vegetation
herbivore
change in biomass of one trophic level causes change in other trophic level

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V->H

increase in vegetation means increase in herbivores

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V

increase in herbivores causes decrease in vegetation

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VH

feedback flows in both directions

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bottom-up

unidirectional influence from lower to higher levels N->V->H->P

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top-down

predation limits community organization N

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biomanipulation

altering density of higher level consumers to prevent algal blooms and eutrophication

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stability

commuity's tendency to reach and maintain a relatively constant composition of species

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F.E. Clements

community of plants had one state of equilibrium controlled by climate
biotic interaction caused plants in climax community to function as one superorganism

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A.G. Tansley

differences in soil, topography, etc. created a variety of communities

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H.A. Gleason

viewed communities as chance grouping of organisms because they have similar abiotic requirements

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nonequillibrium model

communities constantly changing after disturbance

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intermediate disturbance hypothesis

moderate levels of disturbance allow for greater species diversity than do low/high levels of disturbance

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low levels of disturbance

allow completely dominant species to exclude less competitive spcies

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high levels of disturbance

creates too much stress, doesn't allow community to rebuild itself

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small scale disturbance creates

different habitats within a community

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ecological succession

recolonization of species after a disturbance

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primary succession

beginning of recolonization in a lifeless area with little soil

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secondary succession

existing community disturbed but soil still in tact

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species-area curve

if all other factors are equal, larger geographic size means more species

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what impacts speciation of islands

immigration/emigration
size and distance from mainland

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island equilibrium model

when rate of extinction = rate of immigration

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pathogens

disease causing microorganisms

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zoonotic pathogens

transferred to humans from other animals via direct contact of through an intermediate