Populations and Ecosystems

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Populations and Ecosystems
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Resources and exponential growth

• A population a group of organisms of one species
  that lives in the same place and the same time
  and can successfully reproduce.
• Growth occurs at a rate higher than what is
  needed to replace individuals that have left or
  died.
• Exponential growth in populations
• Typically short term, in new habitat with lots of
  resources, or when pressures are removed such as
  species protection

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Exponential Growth
. protection
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Exponential Growth and re-introduction

• Cases where habitat has been destroyed in the
  past can deplete a species. Ex. Deforestation
• When the habitat is reinstated it is possible to
  reintroduce the species and as long as the
  resources remain available exponential growth
  will occur.
• Ex. Wild turkeys went from 4400 to 70,000 in 20
  years.

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Limiting Factors

• Exponential growth cannot be sustained naturally
• As the population increases the individuals have
  access to fewer resources
• Abiotic factors also play a huge role

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Carrying Capacity

• Carrying capacity is the size of the population
  that can be supported indefinitely but the
  available resources and services of an ecosystem.
  
• When a population is maintained at carrying
  capacity it is at an equilibrium (Balanced)
• When a resource is being used at a rate that
  exceeds carrying capacity the population will
  drop in relation.
• This resource could be food, but may also be
  abiotic.

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Human Activity and Carrying Capacity

• Urban Sprawl-the spreading of city area across
  natural habitats results in habitat loss. This
  affects the carrying capacity of many species.
• Intensification, building up as opposed to out is
  one solution to prevent habitat loss.

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Interactions Among Species

• Ecological Niche
• The way that an organism occupies a position in
  an ecosystem, including all the necessary biotic
  and abiotic factors.
• Ex. Biotic niche of brown bat
• Insects it eats
• Competitors (common Nighthawk)
• Predators
• Abiotic niche of brown bat
• Places for roosting and hibernation
• Time of night it hunts
• Airspace it flies
• Temperature range it can tolerate