chapter 41
community
a group of populations of different species living close enough to interact
interspecific interactions
competition, predation, herbivory, parasitism, mutualism, commensalism
competition
-/-
strong competition can lead to competitive exclusion principle, character displacement
competitive exclusion principle
two species competing for the same limiting resources cannot coexist in an environment
character displacement
tendency for characteristics to be more divergent in sympatric populations of two species than allopatric populations of the same two species
resource partitioning
differentiation of ecological niches enabling similar species to coexist in a community
exploitation
one feeds off another: predation, herbivory, parasitism
aposematic colouration
neon colourful animals to warn others they are poisonous
batesian mimicry
mimic warning colouration to avoid being eaten
parasitism
parasite derives nutrients from the host harming it
endoparasites
live inside a host
ectoparasites
live on surface of host
social parasites
take advantage of social interactions of host (making them raise their young)
adaptations of avian brood parasites
host selection, synchronize egg paying with hosts, removal of some or all of host clutch or brood, exaggerated begging displays, in ejector species mimicry of host eggs and nestlings
positive interactions
both are not harmed: mutualism (+/+) commensalism (+/0)
mutualism
interspecific interaction benefitting both species, can be obligate where one species needs other to survive, or facultative where both can survive alone
commensalism
one species benefits the other is unaffected
species diversity
the variety of organisms that make up the community
species richness
the total number of different species in the community
relative abundance
proportion each species represents of the total individuals in the community
foundation species
exert strong effects on communities due to their large size or high abundance
keystone species
exert strong control on a community by their ecological roles or niches, most important but not always most abundant
ecosystem engineers
cause physical changes to the environment that effect community structure
decades ago ecosystems were thought to run by
maintaining a state of equilibrium
immediate disturbance hypothesis
moderate levels of disturbance can foster greater diversity than either nigh or low levels of disturbance