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population - group of single species living in a certain place

  • size, density, dispersion, demographics
  • population range - area throughout which a population occurs
    • no population occurs in all habitats around the world
    • changes as the environment changes
  • dispersion - how organisms are spaced
    • randomly spaced - when organisms don’t interact much
    • uniformly spaced - due to competition for resources
    • clumped spacing - most common form, due to strong social interaction or important resource in a certain area
    • human effect - humans altering the environment changes dispersion
  • metapopulations - networks of distinct populations that exchange individuals
    • occurs where suitable habitats separated by unsuitable habitats
    • source-sink metapopulations - organisms sent from better areas (source) to bolster worse areas (sink)
  • population growth - will exceed resources if unchecked
    • sex ratio - number of births directly related to number of females
    • generation time - average interval between birth of individual and its offspring
    • cohort - group of individuals of the same age
    • survivorship - percentage of original population that survives to given age
  • biotic potential - rate population will grow if no limits exist
  • sigmoidal growth curve - shows limits of population growth due to carrying capacity
  • density-dependent factors - based on the number of organisms
    • population increases >> mortality increases or birth rates decline (negative feedback)
    • Allee effect - where growth rate actually increases as population increases
    • resources, disease, increased aggression, hormonal changes
  • density-independent factors - natural disasters

r strategy - rapid population growth

  • suited for populations far below carrying capacity
  • small, short-lived growth phase
  • reproduces rapidly w/ large litters

K strategy - low rate of growth

  • suited for populations near carrying capacity
  • takes longer to get to carrying capacity (K)
  • longer generations, smaller litters
  • extended parental care
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