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Notes: Populations

Learn different methods to determine population size, observe direct & indirect factors, analyze population changes, and understand density & limiting factors in ecology. Explore ways populations evolve and adapt.

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Notes: Populations

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  1. Notes: Populations Chapter 11 Section 2

  2. Ways to determine population size

  3. 1. Direct Observation • Count all the members.

  4. 2. Indirect Observation • Use tracks or other signs to determine population size.

  5. 3. Sampling • Counting the number of organisms in a small area and multiplying to estimate ( an approximation of a number based on reasonable assumptions) the number in a larger area

  6. 4. Mark and Recapture • Animals are first captured and marked and then released in the environment. Then another group is captured.

  7. Population Changes • Populations can change in size when new members join the population or when members leave the population.

  8. 1. Increase Size • Birth adds new members. The birth rate is the number of births per 1000 individuals for a given time period. • Immigration - members moving into a population

  9. 2. Decrease Size • Death - the death rate is the number of deaths per 1000 individuals for a given time period. • Emigration - individuals leaving a population

  10. Population Statement • If birth rate > death rate, population size increases. • If death rate > birth rate, population size decreases.

  11. A. Population Density • The number of individuals in a certain area. • Population Density is equal to #of individuals divided by the area.

  12. Limiting Factors • An environmental factor that causes a population to decrease.

  13. Examples of limiting factors 1. Food and water 2. Space3. Weather

  14. Carrying Capacity • The largest population that an environment can support.

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