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Bellringer

Explore the reasons behind population decrease, including density-dependent and density-independent limiting factors such as deforestation, predation, disease, natural disasters, competition, parasitism, and severe weather events. Engage in a creative writing exercise to understand the impact on populations.

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Bellringer

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  1. Bellringer • List 3 reasons why a population might decrease in size

  2. Population • Limiting Factor: A factor that causes population growth to decrease • 2 Types: • 1. Density-dependent: Factors that depend on the size of the population • Only become limiting when the population density becomes very high • Effects are intensified as the pop. Density increases • 2. Density-independent: Factors that do not depend, or are independent, of the size of the population • Are limiting regardless of the size of the population • Affect allpopulations in similar ways

  3. Limiting Factors

  4. Deforestation • Density-Independent • Human activities • Deforestation; over-hunting/fishing • Effects are harmful on population regardless of size

  5. Predation • Density-Dependent • Predation • The effect of predation intensifies as the population density of predators increases.

  6. Disease • Density-Dependent • Disease • High population densities make the spread of disease easier to transmit

  7. Natural Disasters • Density-Independent • Natural Disasters • Hurricane, tornado, flood, severe drought • Equally devastating to populations regardless of size

  8. Competition • Competition: • More members of a population = Less Available resources = More competition • Less members of a population = More available resources = Less competition

  9. Parasitism • Density-Dependent • Parasitism • High densities make it easier for parasites to find hosts, and spread diseases

  10. Severe frost • Density-Independent • Weather • Extremely hot/cold temperatures; frost • Adversely effects all populations regardless of their size.

  11. Creative Writing • Each group will work together to develop the beginning of a story. • Introduce your characters, setting, problem (limiting factor), and size of population in that characters community • Pass your story to the next group 2. Each group will read the introduction of the their new story, and: • Explain how the characters are being affected by the problem introduced in Part 1 (what fears/concerns does this organism have for his/herself and his population • Pass your story to the next group 3. Each group will read their new story, and write its ending: • Explain what happened to the character and his/her population as a result of the problem; will they be doing anything to re-build their population? • Explain the impact this problem had on the overall population size?

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