Chapter 54: Community Ecology Flashcards
community
group of populations of different species living close enough to interact
interspecific interactions
competition, predation, herbivory, symbiosis, facilitation
competition
-/- interaction involving individuals of different species competing for a resource that limits their growth and survival
competitive exclusion
two species cannot coexist in the same place permanently if they compete for the same resources
ecological niche
summary of a species’ use of biotic and abiotic resources
resource partitioning
differentiation of niches that enables similar species to coexist in a community (indicates past competition and evolution of niches)
fundamental niche often differs from
actual niche
character displacement
tendency for characteristics to diverge more in geographically overlapping populations than in geographically separate populations
geographically overlapping
sympatric
geographically separate
alopatric
predation
+/- interaction in which predator kills and eats prey
cryptic coloration
camouflage makes it difficult to see prey
aposematic coloration
bright warning coloration
disruptive coloration
makes outline of prey harder to see (stripes on a zebra)
batesian mimicry
harmless species imitate a harmful species
mullerian mimicry
two or more harmful species imitate each other
herbivory
+/- interaction in which organism eats parts of a plant or alga
types of symbiosis
parisitism, mutualism, commensalism
parasitism
+/- interaction in which parasite derives nutrients from the host
endoparasites
parasites that live inside body
ectoparasites
parasites that live on the external surface of the body
mutualism
+/+ interaction in which both species benefit
obligate mutualism
two species cannot survive without each other
facultative mutualism
two species can survive on their own
commensalism
+/0 interaction in which one species benefits and the other is unaffected
facilitation
+/+ or +/0 interaction without living intimately as in symbiosis
example of facilitation
trees shade ground and make soil more hospitable for salt marsh plants
species diversity
variety of organisms that make up a community
species richness
of different species
relative abundance
proportion each represents of all individuals in the community
Shannon diversity
H= -(plnp + plnp + …) p=relative abundance
higher H means more diversity
more diverse communities tend to have
higher productivity and more stability
trophic structure
feeding relationships between organisms
food chain
transfer of energy from primary producer to consumers to decomposers
food webs
food chains linked together
energetic hypothesis
length of food chain is limited by inefficiency of food transfer (10%)
biomass
total mass of all individuals in a population
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
dominant species
species that are most abundant/have highest biomass
keystone species
not usually abundant in a community but has control due to specific niche/role
ecosystem engineers
species that dramatically alter their environment
what do V, H, and arrows mean
vegetation
herbivore
change in biomass of one trophic level causes change in other trophic level
V->H
increase in vegetation means increase in herbivores
V
increase in herbivores causes decrease in vegetation
VH
feedback flows in both directions
bottom-up
unidirectional influence from lower to higher levels N->V->H->P
top-down
predation limits community organization N
biomanipulation
altering density of higher level consumers to prevent algal blooms and eutrophication
stability
commuity’s tendency to reach and maintain a relatively constant composition of species
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
A.G. Tansley
differences in soil, topography, etc. created a variety of communities
H.A. Gleason
viewed communities as chance grouping of organisms because they have similar abiotic requirements
nonequillibrium model
communities constantly changing after disturbance
intermediate disturbance hypothesis
moderate levels of disturbance allow for greater species diversity than do low/high levels of disturbance
low levels of disturbance
allow completely dominant species to exclude less competitive spcies
high levels of disturbance
creates too much stress, doesn’t allow community to rebuild itself
small scale disturbance creates
different habitats within a community
ecological succession
recolonization of species after a disturbance
primary succession
beginning of recolonization in a lifeless area with little soil
secondary succession
existing community disturbed but soil still in tact
species-area curve
if all other factors are equal, larger geographic size means more species
what impacts speciation of islands
immigration/emigration
size and distance from mainland
island equilibrium model
when rate of extinction = rate of immigration
pathogens
disease causing microorganisms
zoonotic pathogens
transferred to humans from other animals via direct contact of through an intermediate
