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all organisms within a particular area
Interspecific interactions include what 7 things?
define ecological niche.
the sum of a species use of the biotic and abiotic resources in its environment (how and where it makes its living)
what is the competitive exclusion principle?
2 species cannot occupy the same ecological niche
how does competition allow the competitive exclusion principle to exist? (4)
- a superior competitor may drive other species to extinction
- competition may limit a species to a more limited niche than it might otherwise occupy.
- species with similar niches may come to subdivide the niche
- direct competition may push sympatric populations of 2 species to become diff
what is resource partitioning?
species with similar niches may come to subdivide the niche
what is character displacement? what is an example?
- direct competition may push sympatric populations of 2 species to become different
- ex. diff bird beaks reflect diff seed sizes
what is predation? what can it drive?
- one species kills the other and eats it
- can drive evolutionary "arms race"
how have predators evolved? (4)
- good sensory systems
how have prey evolved? (6)
- hiding behaviour
- cryptic colouration
- mechanical defenses
- group defenses
- chemical defenses
how may defenses of predator and prey advertised?
aposematic colouration (warning)
describe the 2 different types of mimicry.
- Mullerian mimicry: several dangerous species resemble each other
- Batesian mimicry: a harmless species resembles dangerous one
what is herbivory?
when plant or algae is partially consumed
what are some plant adaptations to herbivory?
- spines or hairs, cuticle, thick bark fro grittiness (physical defence)
- toxic, distasteful (secondary compounds)
what are some herbivore adaptations to herbivory?
- ability to detect plant (smell, colour, shape)
- ability to overcome host defences
what is parasitism?
parasite harms the host (doesn't kill right away)
Describe the 2 types of parasites. what are some examples?
- ectoparasites: found on outside of the host ex. leeches, lice
- endoparasites: feed inside of host ex. flukes, tapeworms
what is the lifecycle of flukes? (6)
- fluke eggs (in bird feces) land in water
- snails eat feces
- flukes exit snails into water
- flukes frill into fish
- fish eaten by birds
- fluke eggs in bird feces
what is the fluke lifecycle consequence to crabs? (5)
- infected snails grow slow and reproduce less= less snails
- less algae eaten by snails=more algae
- more cover for remaining snails
- harder for crabs to find snails= less crabs
what is diseases? what can it cause?
- mostly due to microscopic pathogens: viruses, bacteria, fungi, protists
- can cause decline of susceptible host species
what is mutualism? what is an example?
- evolved interactions that favour both species
- flowering plants and pollinators
what is commensalism?
one species benefits; other neither gains nor loses
Most of the preceding interactions have been shaped through ____________.
what is species diversity? what are the 2 components?
- variety of diff kinds of organisms
- 2 components= species richness (# of species) and relative abundance of each species (variety)
Energy and nutrients flow through __________ or _________.
Are there limits to food chain lengths? why?
- limited length because energy transfer between trophic levels is usually <20% efficient therefore not enough energy to support many trophic levels
what are the 4 community characteristics?
- species diversity
- feeding relationships
- the role of one or two key species (species with large impact)
- response to disturbance
what is a dominant species?
- are most abundant or have greatest biomass
- influence with other species, can survive there
what are keystone species?
need to be abundant but act to maintain diversity
what are ecosystem engineers? what is an example?
- ecosystem engineers cause physical changes that affect community structure
- beavers building dams and termites
what is ecological succession?
gradual, predictable change in community structure after a disturbance
what is primary and secondary succession?
- primary succession= gradual, predictable change in community structure after a disturbance that begins from bare rock
- secondary succession= gradual, predictable change in community structure after a disturbance that begins from intact soil
why does succession occur?
each stage creates conditions that favour the next stage or inhibits members of current stage
Is a finals Climax community ever reached?
yes to an extent
community diversity is affected by _____________________.
There is greater diversity in ________ habitats. why? (2)
- more energy and maybe a more stability
- more species in bigger communities
what does they island equilibrium model predict?
predicts that species number is related to "island" size and distance to a "mainland"
More species on an island, lower __________________________. why?
lower the arrival rate of new species because most of these species are already on the island; and more extinctions (of new arrivals) because more competitive exclusion
what are the implications for conservation? (3)
- immigration and extinction rates
- effect of island size
- effect of distance from mainland
what are the 2 hypothesis that suggest why certain communities exist and not others?
Individualistic hypothesis: plant species there simply have similar ecological requirements
Integrated Hypothesis: community is an association of ecologically-linked species interact in some way