ch. 54 part 1 Flashcards
community
assemblage of populations of various species living close enough for potential interaction
interspecific interactions
relationships between species in a community
ex. of interspecific interactions
- competition
- predation
- herbivory
- parasitism
- mutualism
- commensalism
how can interspecific interactions be summarized
positive, negative, no effect
competition
species compete for resource in short supply that limits survival and reproduction
what can strong competition lead to
competitive exclusion
competitive exclusion
local elimination of a competing species
G.F. Gause
Russian ecologist that concluded that 2 species competing for the same limiting resources cannot coexist permanently in the same place
ecological niche
sum of an organism’s use of biotic and abiotic resources - ecological role
how can ecologically similar species coexist in a community
if there are one or more significant differences in their niches
resource partitioning
differentiation of ecological niches, enabling similar species to coexist in a community
temporal partitioning of common spiny and golden spiny mouse
- both normally nocturnal
- where they coexist, golden spiny becomes diurnal (active during day)
fundamental niche
niche potentially occupied by that species
realized niche
niche actually occupied by that spcies
character displacement
tendency for characteristics to be more divergent in sympatric populations of 2 species than in allopatric populations of the same 2 species
sympatric
occurring within the same geographical area - overlapping in distribution
allopatric
occurring in separate non-overlapping geographical areas
exploitation
any +/- interaction in which one species benefits by feeding on the other species
exploitative interactions include:
- predation
- herbivory
- parasitism
predation
interaction in which one species (predator) kills and eats the other (prey)
what do predators have adaptations for
finding, identifying, catching, and subduing prey
what adaptations do prey have
to avoid being eaten - behavioral defenses
aposematic coloration
bright warning coloring in animals w/ effective chemical defenses
cryptic coloration
camouflage - makes prey difficult to spot
Batesian mimicry
palatable/harmless species mimics and unpalatable or harmful model
Mullein mimicry
2+ unpalatable species resemble each other
what can mimicry do for predators
enable them to approach prey
herbivory
interaction in which an herbivore eats parts of a plant or algae
what are most herbivores
invertebrates
specialized adaptations of herbivores
- specialized teeth and digestive systems
plants defenses against herbivory
- toxic/distasteful chemicals
- mechanical defenses (spines/thorns)
parasitism
one organism (parasite) derives nourishment from another organism (host), which is harmed in process
endoparasites
parasites that live within body of their host
ectoparasites
parasites that live on the external surface of a host
life cycle of many parasites can involve what?
multiple hosts
why do some parasites change the behavior of their host?
to increase the likelihood that the parasite will be transmitted to the next host
what can parasites affect
survival, reproduction, density of host population
- directly/indirectly
positive interactions
at least one species benefits and neither is harmed
mutualism
positive interaction for both species involved
commensalism
positive for one species, neutral (neither harmed nor helped) for other species
2 fundamental features of community structure
- species diversity
- feeding relationships
in some cases, a few species in a community exert strong control on _____________
that community’s structure
species diversity
variety of organisms that make up the community
2 components of species diversity
- species richness
- relative abundance
species richness
number of dif species in the community
relative abundance
proportion each species represents of all ind. in the community
communities w/ higher diversity are:
- more productive - produce more biomass
- more stable
- can withstand/recover from environmental stresses
- more resistant to invasive species
invasive species
organisms that become established outside their native range
trophic structure
feeding relationships between organisms in a community
food chains
link trophic levels from producers to top carnivores
trophic level
position an organism occupies in a food chain
trophic levels from bottom to top
- primary producers
- primary consumers
- secondary consumers
- tertiary consumers
- quaternary consumers
food web
group of food chains linked together forming complex trophic interactions
does a species only play one role on one trophic level?
no - can play more
how can food webs be simplified:
- group species w/ similar trophic relationships
- isolate portion of community that interacts very little w/ rest of community
how long is each food chain in a food web
only a few links long
energetic hypothesis
length of food chain is limited by inefficient energy transfer
how much of energy stored in organic matter at each trophic level is converted to organic matter at the next trophic level?
10%
what can also limit the length of the food chain
carnivores tend to be larger at higher trophic levels
- can’t obtain enough food from small prey efficiently enough to meet metabolic needs
