Population Ecology

• Exponential growth


  When a population's per capita growth rate stays the same regardless of the population size, making it grow faster and faster
• Carrying capacity


  Limit on population size of a population imposed by limited resources in the environment
• Logistic growth

  When a population's per capita growth gets smaller and smaller as it reaches its carrying capacity
• Population growth rate


  dN/dT = rN
• Biotic potential


  dN/dT = rmaxN
• Biotic potential


  The maximum population growth rate of a speices
• Intraspecific competition


  Competition between members of the same population caused by limited resources, influences carrying capacity
• Density dependent limiting factors


  As there are more individuals in a population, the amount of resources decreases per capita until it is no longer able to support everyone properly, leading to limitations on the size of the population
• Density dependent limiting factors examples:

  • Competition within the population
  • Predation (when bigger populations attract predators)
  • Waste accumulation (when too much waste is produced, which becomes toxic and starts killing organisms off)
• Density independent limiting factors

  • Natural disasters
  • Severe weather
  • Pollution
• Density independent limiting factors


  Kills of chunks of a population regardless of size and are often sporadic. Can wipe out entire small populations, and tend to last less long
• Dispersion


  The pattern of spacing among individuals within the boundaries of a population
• Competition


  In crowded populations, increasing population density means less resources available which may cause a decrease in population size