Ecology

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Anonymous
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30829
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Ecology
Updated:
2010-08-22 21:24:56
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eco
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Eco
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  1. population
    group of individuals all of the same species living in the same area
  2. Community
    group of population living in the same area
  3. Ecosystem
    the interrelationships between the organisms in a community and their physical environment
  4. Biosphere
    all of the regions of the earth that contain living things
  5. Habitat
    where and organism lives
  6. Niche
    all the biotic (living) and abiotic (nonliving) resources in the environment used by an organism
  7. Population ecology
    study of the growth, abundance, and distribution of populations
  8. Size
    • represented by N
    • total number of individuals in the population
  9. density
    total number of individuals per unity area or volume occupied
  10. dispersion
    how individuals in a population are distributed
  11. age structure
    • description of the abundance of each age
    • horizontal bars are tiers of the diagram that represent the frequency of individuals in a particular age group
    • vertical line down divides each group into gender
  12. survivorship curve
    how mortality of individuals in a species varies during their lifetimes
  13. Type 1
    • describes most individuals survive to middle age
    • after middle age, mortality is high
    • ex. Humans
  14. Type II
    curve that describes organisms which length of survivorship is random
  15. Type III
    • describes that most individuals die young
    • only a little bit survive to become adults
  16. biotic potential
    max growth rate of a population under ideal conditions with unlimited resources and without any growth restrictions
  17. factors that contribute to biotic potential
    • age at reproductive maturity
    • clutch size (number of offspring produced at reproductive event)
    • frequency of reproduction
    • reproduction lifetime
    • survivorship of off spring to reproductive maturity
  18. carrying capacity
    maximum number of individuals of a population that can be sustained by a particular habitat
  19. limiting factors
    • elements that prevent a population form attaining its biotic potential
    • density-dependent-factors are those agents whose limiting effect becomes more intense as the population density increases. Ex. parasites nd diseases
    • density-independent-factors occur independently of the density of the population. ex. natural disasters, and extreme climates
  20. exponential growth
    • occurs whenever the reproductive rate is greater than zero
    • population size is plotted against time
    • plot of exponential growth rises quickly forming a J-shaped curve
  21. logistic growth
    • occurs when limiting factors restrict the size of the population to the carrying capacity of the habitat
    • S-shaped curve
    • population increases, its reproductive rate decreases until at carrying capacity size stabilizes
  22. population cycles
    fluctuations in population size in response to carrying effects of limiting factors
  23. r-selected species
    • exhibits rapid growth (Jshaped curve)
    • opportunistic species-quickly invade a habitat, quickly reproduce, and then die
  24. K-selected species
    • one whose population size remains relatively constant
    • produce a small number of large offspring that require extensive parental care until they mature
    • reproduction occurs repeatedly during their lifetimes
    • ex. humans
  25. factors that make exponential growth possible
    • increases in food supply-increase in food due to technological advances
    • reduction in disease-advances in medicine reduced the death rate and increased the birth rate
    • reduction in human wastes-water purification and sewage systems,health hazards from human waste were reduced
    • expansion of habitat-better housing
  26. community ecology
    concerned with the interaction of populations
  27. interspecific competition
    competition between different species
  28. competition is resolved by
    • competitive exclusion principle (Gause's principle)
    • resources partitioning
    • character displacement (niche shift)
    • realized niche
  29. competitive exclusion principle (Gause's principle)
    • when two species compete for exactly the same resources, one is likely to be more successful
    • one species outcompetes that other and eventually the second species is eliminated
    • no two species can sustain coexistence if they occupy the same niche
  30. resource partitioning
    • some species coexist in spite of apparent competition for the same resources
    • species that pursue slightly different resources or securing their resources in slightly different ways
    • individuals minimize competition and maximize success
  31. character displacement (niche shift)
    • result of resource partitioning, certain characteristics may enable individuals to obtain resources in their partitions more successfully
    • selection for these characteristics reduces competition with individuals in other partitions and leads to a divergence of features or character displacement
  32. realized niche
    • niche that an organism occupies in the absence of competing species is its fundamental niche
    • when competitors are present one or both species may be able to coexist by occupying their realized niche, that part of their existence where niche overlap is absent where they do not compete for the same resources
  33. predation

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