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Chapter 5 Populations

Chapter 5 Populations. 5-1 How Populations Grow. How Populations Grow. Characteristics of Populations Three important characteristics of a population geographic distribution Density growth rate. Geographic Distribution. Geographic Distribution

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Chapter 5 Populations

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  1. Chapter 5Populations 5-1 How Populations Grow

  2. How Populations Grow • Characteristics of Populations • Three important characteristics of a population • geographic distribution • Density • growth rate

  3. Geographic Distribution Geographic Distribution • Geographic distribution, or range, is a term that describes the area inhabited by a population.

  4. Geographic Range • @The area inhabited by a population is called its geographic range.@ • A population’s range can vary enormously in size, depending on the species.

  5. Geographic Range • A bacterial population in a rotting pumpkin may have a range smaller than a cubic meter, whereas the population of cod in the western Atlantic covers a range that stretches from Greenland down to North Carolina.

  6. Density and Distribution • An example of a population that shows random distribution is the purple lupine. These wild flowers grow randomly in a field among other wildflowers. The dots in the illustration represent individual members of a population with random distribution.

  7. Density and Distribution • An example of a population that shows uniform distribution is the king penguin. The dots in the illustration represent individual members of a population with uniform distribution.

  8. Density and Distribution • An example of a population that shows clumped distribution is the striped catfish. These fish organize into tight groups. The dots in the illustration represent individual members of a population with clumped distribution.

  9. Population Density • Population density is the number of individuals per unit area. • The population of ducks in a pond may have a low density, while fish in the same pond have a higher density

  10. Brainstorm • What are three ways population size can be affected?

  11. Populations Growth • Population Growth • Three factors can affect population size: • number of births • the number of deaths • the number of individuals that enter or leave the population. * Simply put, a population will increase or decrease in size depending on how many individuals are added to it or removed from it

  12. Birthrate and Death Rate • @A population can grow when its birthrate is higher than its death rate. @ • If the birthrate equals the death rate, the population may stay the same size. • If the death rate is greater than the birthrate, the population is likely to shrink.

  13. Word Origin • Immigration is formed from the Latin prefix in-, meaning “in,” and migrare, meaning “to move from one place to another. • If the Latin prefix e- means “out,” then which of the following means “migration out”? • A.) emigration • B.) migration • C.) Immigration

  14. Immigration & Emmigration • Immigration • the movement of individuals into an area, is another factor that can cause a population to grow. • Emigration • the movement of individuals out of an area, can cause a population to decrease in size.

  15. Exponetial Growth • Exponential Growth • If a population has abundant space and food, and is protected from predators and disease, then organisms in that population will multiply and the population size will increase.

  16. Exponential Growth Exponential growth occurs when the individuals in a population reproduce at a constant rate. @Under ideal conditions with unlimited resources, a population will grow exponentially.@

  17. Checkpoint Which of the following is NOT a condition for a population to reach exponential growth? A.) presence of unlimited resources B.) Absence of predation and disease C.) movement of individuals out of the population

  18. Logistic Growth • Logistic growth occurs when a population's growth slows or stops following a period of exponential growth. • @As resources become less available, the growth of a population slows or stops.@The general, S-shaped curve of this growth pattern, called logistic growth

  19. Phase 1: Exponential Growth • @During this phase, resources are unlimited, so individuals grow and reproduce rapidly.@

  20. Phase 2: Growth Slows Down. • In real-world populations, exponential growth does not continue for long. @At some point, the rate of population growth begins to slow down.@

  21. Phase 3: Growth Stops. • At some point, the rate of population growth drops to zero and the size of the population levels off.

  22. Carrying Capacity • Carrying Capacity  The number or the largest number of individuals that a given environment can support.

  23. List three characteristics that are used to describe a population. What factors can change a population's size? What is the difference between exponential growth and logistic growth?

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