This document discusses key concepts related to studying populations. It defines population density as the number of individuals in an area. It explains that ecologists estimate population sizes through direct observation like counting, indirect observation of signs, or sampling a small area and extrapolating. An estimate is an approximation based on reasonable assumptions. Sampling is used when counting every member is not possible. Populations change size due to new members entering or leaving through birth, death, immigration, and emigration. Birth rate is the number of births and death rate is the number of deaths over a period of time. Limiting factors prevent population growth, such as food, space, and weather conditions. Carrying capacity is the largest population an environment can support.

1. Studying Populations Mr. Schumaier

2. What is POPULATION DENSITY? 1

3. The number of individuals in an area 1

4. How do ecologists determine the size of a population? 2

5. 2 Direct Observations Counting one by one all members of a species in an area.

6. 2 Indirect Observations Observing tracks or other signs rather than the organisms themselves.

7. 2 Sampling Ecologists make an estimate. Count the number in a small area then multiply to find for a larger area

8. 2 Mark-and-Recapture Animal is captured, marked, and then released into the environment. They are then recaptured and counted.

9. What is an ESTIMATE? 3

10. An approximation of a number, based on reasonable assumptions. 3

11. When is sampling used to estimate a population? 4

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. 4

13. What causes populations to change in size? 5

14. New members enter the population or members leave the population. 5

15. What do scientists mean by BIRTH RATE & DEATH RATE? 6

16. Birth Rate Number of births in a population in a certain amount of time. 6 Death Rate Number of deaths in a population in a certain amount of time.

17. What is IMMIGEATION? 7

18. Moving into a population. 7

19. What is EMIGRATION? 8

20. Leaving a population 8

21. What is a LIMITING FACTOR? 9

22. An environmental factor that prevents a population from increasing. 9

23. What factors limit population growth? 10

24. Food Space Weather Conditions 10

26. What is an environments CARRYING CAPACITY? 11

27. The largest population that an environment can support. 11

30. How can space & weather limit population growth? 12

31. Space – If organisms are crowded, some will not be ale to reproduce or even survive. 12 Weather – Severe weather conditions can kill many members of the population.

32. The End