Populations and Resources

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Populations and Resources
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Population

• Is a group of organisms of one species that lives
  in the same place, at the same time, and can
  successfully reproduce.
• Example Elephants.

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Exponential Growth

• Accelerating growth that produces a J-like curve
  when the population is graphed.
• Only occurs for short periods in nature
• Usually when the organism has a lot of resources.

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Limiting Factors

• Exponential growth cannot be sustained in nature
  because no ecosystem has an unlimited supply of
  resources.
• These restrictions are called limiting factors.
• Abiotic limiting factors temperature, pH,
  oxygen, light, hiding places
• Biotic limiting factors food, etc.

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Carrying Capacity

• Is the size of a population that can be supported
  indefinitely by the resources and services of an
  ecosystem.
• When a population is maintained at its carrying
  capacity, it is at an equilibrium or balance.
• There is an equal amount of organisms being born
  or moving into the ecosystem as there are dying
  or leaving.

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Graphing Carrying Capacity
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Humans and Carrying Capacity

• Humans alter natural ecosystems often, causing a
  change to carrying capacities.
• Urban sprawl is the growth of relatively
  low-density development on the edges of urban
  areas.
• Human population in the Golden Horseshoe is
  expected to increase by 3.7 million between 2005
  and 2031. How do we make room for all these
  people without affecting other ecosystems?

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Ecological Niche

• As species go about their daily activities, they
  interact with other species.
• An ecological niche is the way an organism
  occupies a position in an ecosystem, including
  abiotic and biotic factors.

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Example brown bat

• Biotic niche insects that it eats, its
  competitors like the nighthawk, and its
  predators.
• Abiotic niche place for roosting and
  hibernation, the time of night it hunts, airspace
  it flies in, the temperature range it can live at.

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Population Regulation

• Predators organism that kills and consumes other
  organisms
• Prey is eaten as food by a predator
• Bottom-Up Population regulation a shortage of
  plant resource at the base of the food chain
  causes declines in the animals in the higher
  trophic levels.
• Top-Down Population regulation more rabbits in a
  population, lead to more coyotes to eat them,
  then more coyotes lead to fewer rabbits.

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Competition

• Competition occurs when 2 or more organisms
  compete for the same resource.
• Can limit size of population
• Can influence the ecological niche of an organism

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Symbiosis

• Mutualism 2 species benefit from the
  relationship
• Example algae lives in coral. The algae gives
  the coral energy and the coral gives the algae
  protection and carbon dioxide.
• Parasitism when an organism benefits at the
  expense of a different organism.

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