1. 13.1 How Populations Change in Size
Unit 13: Population Growth
May 11, 2009
Sanders

2. Unit 13: Population Growth
Human Populations
Human population is currently, 7.3 billion people.
It is estimated by the mid twenty-first century, there will be 9 billion people.
July 1, 2019
Unit 13: Population Growth

3. Equation for Population
Number of Births Number of deaths
>
Number Number
of Immigrants of Emigrants
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Unit 13: Population Growth

4. Unit 13: Population Growth
Herring
A herring can lay a million eggs in a single year.
If all of the eggs hatched and the offspring survived, the Earth would be covered with herring.
July 1, 2019
Unit 13: Population Growth

5. Human Population Growth
It is estimated that the human population will grow at a rate of 94 million people per year.
July 1, 2019
Unit 13: Population Growth

6. How Fast Can a Population Grow?
Each population has a characteristic maximum growth rate.
Biotic potential
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Unit 13: Population Growth

7. What Limits Population Growth?
Populations are limited by habitat constraints.
Habitats have limitations
Food
Water
Shelter
July 1, 2019
Unit 13: Population Growth

8. Unit 13: Population Growth
Limiting Factors
Limiting resources are resources that limit population.
For animals
Food
Water
Shelter
Nesting sites
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Unit 13: Population Growth

9. Unit 13: Population Growth
Limiting Factors
Limiting factors for plants include:
Water
Sunlight
Mineral nutrients
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Unit 13: Population Growth

10. Environmental Resistance
All combined factors to limit resources are the environmental resistance.
What is limiting the fish population?
July 1, 2019
Unit 13: Population Growth

11. Unit 13: Population Growth
Carrying Capacity
Populations will ceases to grow as it reaches and sometimes exceeds its carrying capacity.
Carrying capacity is the maximum population that an environment can support.
July 1, 2019
Unit 13: Population Growth

12. Unit 13: Population Growth
July 1, 2019
Unit 13: Population Growth

13. Unit 13: Population Growth
Carrying Capacity
At first the population increases according to its biotic potential. Environment resistance slows the population’s growth as it approaches its carrying capacity.
Changes in weather and other natural resources cause the population to continue fluctuating over time.
July 1, 2019
Unit 13: Population Growth

14. Carrying Capacity
The graph shows the growth of a population over time. At first the population increases according to its biotic potential. Environment resistance slows the population’s growth as it approaches its carrying capacity. Changes in weather and other natural resources cause the population to continue fluctuating over time.