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• Studying Populations

• Mr. Schumaier

2. What is POPULATION DENSITY?

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3. The number of individuals in an area

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4. How do ecologists determine the size of a population?

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Direct Observations Counting one by one all members of a species in an area. 6.

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Indirect Observations Observing tracks or other signs rather than the organisms themselves. 7.

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Sampling Ecologists make an estimate. Count the number in a small area then multiply to find for a larger area 8.

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Mark-and-Recapture Animal is captured, marked, and then released into the environment.They are then recaptured and counted. 9. What is an ESTIMATE?

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10. An approximation of a number, based on reasonable assumptions.

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11. When is sampling used to estimate a population?

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12. Sampling is used when it is not possible to count every member of a population because there are too many, they are too spread out, or not all the members of the population can be found.

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13. What causes populations to change in size?

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14. New members enter the population or members leave the population.

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15. What do scientists mean by BIRTH RATE & DEATH RATE?

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16. Birth Rate Number of births in a population in a certain amount of time.

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Death Rate Number of deaths in a population in a certain amount of time. 17. What is IMMIGEATION?

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18. Moving into a population.

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19. What is EMIGRATION?

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20. Leaving a population

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21. What is a LIMITING FACTOR?

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22. An environmental factor that prevents a population from increasing.

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23. What factors limit population growth?

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24. Food Space Weather Conditions

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25. 26. What is an environments CARRYING CAPACITY?

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27. The largest population that an environment can support.

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28. 29. 30. How can space & weather limit population growth?

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31. Space If organisms are crowded, some will not be ale to reproduce or even survive.

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Weather Severe weather conditions can kill many members of the population. 32.

The End