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POPULATIONS

SC STANDARD B-6. 2: Students will demonstrate an understanding of the way populations are affected by density-dependent factors & density-independent factors. POPULATIONS. CN page Topic: Populations EQ: What factors affect population size?. How do Populations Grow?.

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POPULATIONS

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  1. SC STANDARD B-6. 2: Students will demonstrate an understanding of the way populations are affected by density-dependent factors & density-independent factors. POPULATIONS

  2. CN page • Topic: Populations • EQ: What factors affect population size?

  3. How do Populations Grow? • 3 important characteristics of a population are its : • geographic distribution • density • growth rate

  4. Geographic Distribution • is the range or area where the organism is found

  5. Hooker’s Manzanita • found in maritime chaparrel (threatened habitat due to development) • Central California (Monterrey County)

  6. Franklin’s Bumble Bee • Most restricted geographic distribution of any known bee • Between Pacific coast & Sierra Nevada in Oregon & northern California

  7. Density • population density: the # of individuals per unit area • Density is one of the main characteristics that describes a natural population.

  8. Growth Rate • 3 factors affect population growth: • 1. # of births • 2. # of deaths • 3. # of individuals that immigrate or emmigrate • Immigration: movement of individuals into an area • Emmigration: movement of individuals out of an area

  9. EXPONENTIAL GROWTH • growth pattern in which the individuals in a population reproduce at a constant rate • Under ideal conditions with unlimited resources, a population will grow exponentially

  10. LOGISITIC GROWTH • growth pattern in which a population’s growth rate slows or stops following a period of exponential growth • carrying capacity: largest # of individuals of a population that a given environment can support

  11. Carrying Capacity Graph

  12. Limiting Factors to Growth • In respect to populations a limiting factor is anything that causes population growth to decrease. • Limiting factors are either: • Density-Dependent • Density-Independent

  13. Density-Dependent Limiting Factors • limiting factor that depends on population size • become limiting only when population density reaches a certain level • Include: • 1. competition • 2. predation • 3. parasitism & disease

  14. 1. Competition When populations become crowded members of same or different species compete for food, shelter, mates, space, sunlight

  15. 2. Predation • Predator-Prey relationships mechanism of population control

  16. 3. Parasitism & Disease • Parasites take nourishment from their host  host weakens  does not usually die

  17. Density-Independent Factors • affect all the populations in similar ways, regardless of #’s • Forest fires • Floods • Seasonal cycles • Human interference (clear-cutting, damming river)

  18. Human Population Growth • Population of humans on Earth increases with time

  19. Patterns of Population Growth • Birth rates, death rates, & the age structure of a population help predict why some countries have high growth rates while other countries grow slowly.

  20. The Demographic Transition • the change in a population from high birth & death rates to low birth & death rates

  21. Complete concept map from page 134 of book on page of notebook (landscape)

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