1. Unit 3 Population Biology Ms. AJ

2. What is a Population?  Group of organisms, all of the same species that live in a same area.  Examples: Herd of cattle Town of people Pride of Lions

3. Populations can do one of 3 things:  Get Bigger  Get Smaller  Stays the same (constant)

4. Populations can change due to different “factors”  What factors will cause a population to change? Disease Competition for food, water, shelter, and space Reproduction Natural Disasters

5. What is density?  Density of a population: The number of individuals in a PARTICULAR AREA.  Which country do you think that’s the highest population density?

6. What is density?  Mexico– 63 people  Japan-349 people  Kenya-78 people  Russia-5 people  United States-35 people

7. What is Density? Which state do you think has the highest population density? New Jersey– 1210 people/mi Which state has the lowest population density? Alaska—1.3 people/mi Wyoming-4.5 people/mi

8. What makes a Population Change?  Populations change based on the number of individuals entering or exiting a population at any given time. If the population is getting larger (GROWING) If the population is getting smaller (DECLINING) Births exceed deathsDeaths exceed births Immigration (in) exceeds emigration (out) Emigrations exceed Immigrations

9. Population Math  If Birth rate is Greater (>) than Death rate → Population Increases ↑  If Death rate is Greater (>) than Birth Rate → Population Decreases ↓  If Birth rate Equals (=) Death Rate → Population Stays the same

10. On the graph, at what points is birth rate more than death rate?

11. At what point is birth rate less than death rate?

12. Where are birth rate and death rate equal?

13. Population Math At the spot marker “I” – the BIRTH RATE is greater (>) than the DEATH RATE

14. Population Math Which of the following best describes the spot marker II? A.BR>DR B.DR>BR C.DR=BR D.All of these are true

15. Population Growth: A Closer Look  Populations do not increase in a straight line; they increase in a J-shape.  Increase is slow at first because there are only a few reproducing individuals, then grows faster because there are more reproducing individuals.

16. Population Growth: A closer look  This type of curve shows EXPONENTIAL growth: as a population gets larger, it also grows at a faster rate

17. Population Growth: A closer look  Populations do not increase forever

18. Population Growth: A closer look  Eventually population levels out due to limited resources, food, space, and mates.  This leads to an “S” Shaped curve (logistic growth) for population growth.

19. Carrying Capacity  The number of organisms of one species than an environment can support.

20. Carrying Capacity  When a population is developing in an environment, there are more BIRTHS than DEATHS and the population increases until the carrying capacity is reached or passed.

21. Where is the carrying capacity of this population? Question?  During which years is the population experiencing exponential growth?

22. Where is the carrying capacity of this population? Question?  During what year did this population reach carrying capacity?

23. Where is the carrying capacity of this population? Question?  What is the carrying capacity for the population at the left?

24. Where is the carrying capacity of this population? Question?  What is the carrying capacity for the population at the left?

25. Where is the carrying capacity of this population? Question?  What are some possible reasons that the population drops after the point shown by the arrow?

26. Population Density  Population Density: The number of individuals in a given area.

27. Limiting Factors  A limiting factor is any biotic or abiotic factor that restricts the existence, numbers, reproduction, or distribution of organisms.

28. There are two types of limiting factors  Density-Independent Factor reduces a population regardless of the population’s size.  Severe Weather  Floods  Fire  Density-Dependent Factor reduces a population which occurs with increasing population density.  Food Shortages, Predation  Lack of Living Space  Disease

29. What affects population density (population size)?  Population density: the number of individuals in a give area  Density dependent factors: environmental factors that affect the size of a population and DEPEND on the size of the population 1. Competition (Food, water, mates) 2. Predation-more predators 3. Diseases (parasites) 4. Stress from overcrowding 5. Limited food and water

30. What affects population density (population size)?  Density Independent factors: environmental factors that affect the size of a population but does NOT depend on the size of that population 1. Weather (polar vortex)-temperatures 2. Natural disasters: hurricanes, droughts, fires, volcanic eruption, floods 3. Pesticides 4. Garbage in ocean

31. Density Independent (DI) or Density Dependent (DD)? A flood occurs and some rabbits drown DI There is a shortage of grass to feed the deer population DD A pesticide in the water causes bird eggs to crack when the mother sits on them to incubate DI A volcanic eruption wipes out 3 acres of palm tree in Hawaii DI More coyotes are present in a forest causing the rabbit population to decrease DD Certain seabirds cannot find any space on to lay their eggs DD

32. STOP AND THINK A B C At which point has the population reached carrying capacity?

33. STOP AND THINK A B C At which point has the population have unlimited resources?

34. STOP AND THINK A B C Describe point “C” in terms of birth rate or death rate.

35. STOP AND THINK A B C Give one density DEPENDENT limiting factor that would explain the drop in the size of population at time “C”

36. STOP AND THINK A B C Give one density INDEPENDENT limiting factor that would explain the drop in the size of population at time “C”