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chap 54
community ecology
26
Biology
Undergraduate 2
08/14/2014

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Term
competition
Definition
when individuals of a different species compete for a resource that limits their growth and survival
Term
predation
Definition
one species kills and eats the other
Term
herbivory
Definition
an organism eats parts of a plant or alga
Term
symbiosis
Definition
individuals of two or more species live in direct and intimate contact with one another
Term
fundamental and realized niche
Definition
fundamental niche is the niche that a species could potentially occupy while a realized niche is the niche that the species actually occupies, often due to restrictions caused by the niches of other species
Term
cryptic coloration
Definition
camoflauge
Term
aposematic coloration
Definition
coloration that warns predators that a species is posionous
Term
batesian mimicry
Definition
when a harmless species mimicks a harmful one
ex- larva that looks like a snake
Term
mullerian mimicry
Definition
when a harmless species mimicks another harmless species. the more unpalatable prey, the sooner predators learn to aviod such markings
Term
parasitism
Definition
when a parasite gets its nutrients from a host, harming it in the process
Term
mutualism
Definition
when both species benefit from an interaction. in obligate on species has lost the ability to live without the other. in faculative, both species can survive alone
Term
commensalism
Definition
an interaction that benefits one species but the other is unaffected. often involves one species gaining food inadvertently exposed by the other.
Term
endoparasites
Definition
parastites that live within the host
Term
ectoparasites
Definition
parasites that live on the outside of a host
Term
species richness
Definition
part of species diversity, refers to the number of different species in the community
Term
relative abundance
Definition
part of species diversity, refers to the proportion each species represents of all the individuals in a community.
basis of shannon diversity index:
= -(PalnPa + PblnPb+ ...)
Term
foodchain
Definition
transfer of food energy up through trophic levels
Term
food web
Definition
linked together food chains that illustrate the trophic relationships of a communtity
Term
primary succession
Definition
when ecological succession occurs in a virtually lifeless are where no soil has yet formed
ex- areas uncovered by receeding glacers
Term
secondary succession
Definition
ecological succesion that occurs when an existing community has been cleared by some disturbance that leaves the soil intact
ex- forest fires
Term
define an ecological niche and explain he competitive exclusion principle in terms of the niche concet
Definition
a niche is the a species use of abiotic and biotic resources in its ennvironment. two species cannot coexist permenently in a communiity if their niches are identical. resource partitioning is the differentiation of niches that enables similar species to coexist in a community and character displacement
Term
explain how dominate and keystone species exert stron control on community structure
Definition
dominant species are the most abundant collectively, and thus exert control over the occurance and distribution of other species because they are competitively supperior in exploiting limited resouces or are the most successful at avoiding predition or the impact of disease. ex- maples in the NE US have major impact on abiotic resource ability and environmental factors such as shade, so they control the diversity and abundence of their community
Keystone species are not abundent in a community, but they have strong control over their communities because of their pivitol niches. ex- sea otters
Term
distinguish between bottom up and top down community organization
Definition
there is a unidirectional infulence from lower to higher tropic levels in botom up communities. to change the structure of these communities, you need to alter the biomass of at the lower trophic levels. adding or removing predators does not affect the lower levels. ex- more nutrients = more plants= more rabbits
in top down communities, preditation mainly controls the community organization. predators limit herbivors, which allows more plants to grow. addition or removal of predators affects all lower levels
Term
describe and explain the intermediate disturbance hypothesis
Definition
this hypothesis states that moderate levels or disturbance foster greater species diversity. high disturbance levels reduce diversity by exceeding the tolerances of many species or occuring so ofthen that slow growing species cant keep up and are exluded. low dieturbance levels also lower diversity because the competitively dominate species exlude the less competitive ones.
Term
explain why species richness declines along an equatorial polar gradiant
Definition
species richness is highest at the tropics because these communities are older and polar communites have "started over" after glaciations. the growing season in the tropics is also longer, so there are more speciation events. the warm climate also provides more solar energy and water. a good way to measure this is through evapotranspiration. high evapotranspiration correlates to high species richness.
Term
define zoonotic pathogens and explain, with an example, how they may be controled
Definition
these pathogens are transfered to humans from other speices through direct contact with the infected species or a vector. for example, rabies in animals. the brittish isles are rabies free, and in order to maintain these they quaritine all potential carriers upon enterance to the country, and insure that all members of the community are vaccinated.
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