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Populations

Populations. 7 Billion – Videos 7 Billion – Agree or Disagree Intro to Populations - Notes. http://www.youtube.com/watch?v=sc4HxPxNrZ0. https:// www.youtube.com/watch?v=4B2xOvKFFz4 https://www.youtube.com/watch?v=VcSX4ytEfcE. Understanding Populations.

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Populations

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  1. Populations 7 Billion – Videos 7 Billion – Agree or Disagree Intro to Populations - Notes

  2. http://www.youtube.com/watch?v=sc4HxPxNrZ0 https://www.youtube.com/watch?v=4B2xOvKFFz4 https://www.youtube.com/watch?v=VcSX4ytEfcE

  3. Understanding Populations Population: all the members of a species living in the same place at the same time.

  4. 3 words to describe a population: • Size – (7 billion people on the planet) • Density – (people per square mile) • Dispersion – (distribution or arrangement of its individuals within a given amount of space) • Even • Clumped • Random

  5. Density

  6. Dispersion

  7. How Does a Population Grow? • Growth rate: change in the size of a population over a given period of time. • Positive (+): birth rate > death rate • Zero (0): birth rate = death rate • Negative (-) = birth rate < death rate Change in population size = Deaths - Births

  8. How Fast Can a Population Grow? • Reproductive potential: the maximum number of offspring that a given organism can produce. • Examples: • It would take elephants 750 years to produce 19 million descendents • It would take bacteria a few days to produce 19 million descendents. • What is another organism with a low reproductive rate?

  9. How Fast Can a Population Grow? • High reproductive potential when individuals… • Produce more offspring at a time • Reproduce more often • Reproduce early in life • Examples: • Insects – can reproduce when they are a few hours or days old • Humans – reproduce after a number of years

  10. How Fast Can a Population Grow? • Exponential Growth: when populations grow faster and faster • Occurs when a population has: • Plenty of food and space • No competition or predators

  11. What Limits Population Growth? • Carrying Capacity:the largest population that an environment can support in any given time

  12. What Limits Population Growth? • Limiting resources:a natural resource that is consumed at the same rate at which the ecosystem produces the resource • Example:

  13. Limiting Factors • Food • Water • Sunlight (producers) • Space • Disease • Competition • Predation

  14. Two Types of Population Regulation Density Dependent Density Independent Same species close together Disease spreads from one to the next Death occurs quickly Portion of a population dies regardless of population density Example: Natural disasters (hurricane)

  15. If humans have no natural predators, how is our population controlled?

  16. Human Carrying Capacity? • Current human population: approx 7.12 billion people • Ranges estimated from 4-16 billion people • Hard to estimate how many people this world can hold • Technological innovations • Medical breakthroughs • http://www.census.gov/popclock/

  17. What caused this rapid growth?

  18. What sparked our growth? • Industrial Revolution (~1750) • Modern medicine (20th century) • Death rates DROPPED due to better care • Agricultural Advances • Transportation Advances

  19. Human Population Growth Source: U.S. Census Bureau- World POPclock Projection

  20. What takes us out? Pair and Share (2 min): Humans are at the top of any food web resulting in no natural predators to keep our populations in check… • What are the limiting factors of the human population? • How are we different than other species in regards to population control?

  21. What’s our limiting factor? • Disease: Bubonic Plague, AIDS, Flu, Malaria • Access to food • Access to clean water • Competition (a.k.a. War)

  22. Populations Review • What is growth rate? • What is reproductive potential? • High reproductive potential? • Low reproductive potential? • What are the two reasons that cause a population to have exponential growth? • What is carrying capacity? • What is an example of a limiting factor?

  23. How Many People Can Live on Planet Earth? http://www.youtube.com/watch?v=dN06tLRE4WE • Human population growth • Water • Food

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