Bio 1215- Chapter 17

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  1. define community.
    all organisms within a particular area
  2. Interspecific interactions include what 7 things?
    • competition
    • predation
    • herbivory
    • mutualism
    • disease
    • commensalism
    • parasitism
  3. 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)
  4. what is the competitive exclusion principle?
    2 species cannot occupy the same ecological niche
  5. 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
  6. what is resource partitioning?
    species with similar niches may come to subdivide the niche
  7. 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
  8. what is predation? what can it drive?
    • one species kills the other and eats it
    • can drive evolutionary "arms race"
  9. how have predators evolved? (4)
    • speed
    • good sensory systems
    • camouflage
    • mimicry
  10. how have prey evolved? (6)
    • speed
    • hiding behaviour
    • cryptic colouration
    • mechanical defenses
    • group defenses
    • chemical defenses
  11. how may defenses of predator and prey advertised?
    aposematic colouration (warning)
  12. describe the 2 different types of mimicry.
    • Mullerian mimicry: several dangerous species resemble each other
    • Batesian mimicry: a harmless species resembles dangerous one
  13. what is herbivory?
    when plant or algae is partially consumed
  14. what are some plant adaptations to herbivory?
    • spines or hairs, cuticle, thick bark fro grittiness (physical defence)
    • toxic, distasteful (secondary compounds)
  15. what are some herbivore adaptations to herbivory?
    • ability to detect plant (smell, colour, shape)
    • ability to overcome host defences
  16. what is parasitism?
    parasite harms the host (doesn't kill right away)
  17. 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
  18. 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
  19. 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
  20. what is diseases? what can it cause?
    • mostly due to microscopic pathogens: viruses, bacteria, fungi, protists
    • can cause decline of susceptible host species
  21. what is mutualism? what is an example?
    • evolved interactions that favour both species
    • flowering plants and pollinators
  22. what is commensalism?
    one species benefits; other neither gains nor loses  
  23. Most of the preceding interactions have been shaped through ____________.
  24. 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)
  25. Energy and nutrients flow through __________ or _________.
    • food chains
    • food webs
  26. 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
  27. 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
  28. what is a dominant species?
    • are most abundant or have greatest biomass
    • influence with other species, can survive there
  29. what are keystone species?
    need to be abundant but act to maintain diversity
  30. what are ecosystem engineers? what is an example?
    • ecosystem engineers cause physical changes that affect community structure
    • beavers building dams and termites
  31. what is ecological succession?
    gradual, predictable change in community structure after a disturbance
  32. 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
  33. why does succession occur?
    each stage creates conditions that favour the next stage or inhibits members of current stage
  34. Is a finals Climax community ever reached?
    yes to an extent
  35. community diversity is affected by _____________________.
    biogeographic features
  36. There is greater diversity in ________ habitats. why? (2)
    • tropical
    • more energy and maybe a more stability
    • more species in bigger communities
  37. what does they island equilibrium model predict?
    predicts that species number is related to "island" size and distance to a "mainland"
  38. 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   
  39. what are the implications for conservation? (3)
    • immigration and extinction rates
    • effect of island size
    • effect of distance from mainland
  40. 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
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Bio 1215- Chapter 17
2014-04-10 23:55:57
community ecology

Community Ecology
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