1. Do Now: Bird migration What are some observations you can make of bird populations during winter, spring, fall, & summer?

2. Population, Dynamics, & Growth

3. What is a Population? –A group of individuals of the same species living in the same area at the same time Characteristics of Populations Birth Rate Death Rate Age Structure Survivorship (predator-prey) Immigration Emigration Chapter 4-1

4. Population Density Number of organisms per unit of area

5. How to measure population size? Mark Recapture (goldfish lab) Random Sampling (sunflowers) –In most cases, it is impractical or impossible to count all individuals in a population

6. Mark-recapture –Animals are trapped, marked, and then recaptured after a period of time –Total Population Size: N=MC/R

7. Random sampling Collect data by taking “random” samples in different areas Sunflower activity! Crab activity! Lab activity!

8. Why Use These Techniques? Because individuals within a population are dispersed differently Three dispersion patterns –Clumped –Uniform –Random

9. Clumped There is physical protection There are a lot of nutrients The initial position is close to the parents Most common in nature

10. Clumped

11. Uniform equal space between individuals –Trees in an orchard –Seeds in a garden

12. Random patternless, unpredictable way

13. Some populations exhibit both clumped and uniform dispersion patterns, but on different scales

14. Dynamics & Growth Two growth curves Known as population Growth Curves –J-shaped –S-shaped

15. Do Now: Population Dynamics 1.If some cattle wandered off, would they still be considered part of the population? 2. If a new herd came by, would they be part of the existing population?

16. Population, Dynamics, & Growth

17. Unlimited resources Exponential Growth Model: Ideal Environment (J-shaped curve)

18. Population Growth Curves logistic growth (S-shaped curve) population growth levels off at the carrying capacity (K) Logistically

19. Populations grow exponentially for a while But the population-limiting factors restrict population growth –Lack of food –Lack of Space –Competition –Disease –Predation The Logistic Growth Model: Reality of a Limited Environment

20. Population, Dynamics, & Growth

21. The logistic growth model –Population growth is slowed by limiting factors

22. These factors are known as… Density Dependent Factors Density Independent Factors

23. Density-dependent factors –Food, light, nutrients, water –Increase a population’s death rate –decrease a population’s birth rate

24. Density-independent factors –Includes events seasonal freezing Volcanic eruptions other natural disasters

25. density- independent factors limit population size before density- dependent factors become important Exponential growth Sudden decline

26. What is going on here…

27. Predator-Prey Cycles Low # predators = high # prey As # prey increase, # predators increases High # predators = low # prey As # prey decrease, # predators decrease

29. Do Now: Snowshoe Hare & Lynx Prey Predator Discuss: What is happening to the populations?

30. Do Now: Industrial Revolution How/why did this lead to a population explosion? 1800

31. Do Now: WWII How did this lead to a population decline? 1939-1945

32. Do Now: Medicine & Sanitation How did this lead to a population increase?

33. Demography Study of human population size, density, distribution, movement, birth and death rates Ch.4-2

34. Human Population Growth Rate  Human population growth rate has slowed.  Why? Population Ecology

35.  Human population growth is not the same in all countries.

36. Population Ecology  A population’s age structure is the number of males and females in each of three age groups: pre-reproductive, reproductive stage, & post-reproductive

38. Population Ecology  Concerns about exceeding the carrying capacity  Resources?

39. Survivorship Curves

40. 1. Type I - mortality occurs among the elderly –(e.g., humans in developed countries) 2. Type II - mortality is not dependent on age –(e.g., many species of large birds, squirrels, and fish) 3. Type III - juvenile mortality is extremely high –(e.g., plant and animal species producing many offspring of which few survive, underdeveloped countries)

41. Survivorship

42. Rapid growth Kenya MaleFemale Percentage of population Primary reproductive ages Slow growth United States Female Percentage of population Zero growth/decrease Italy MaleFemale Percentage of population Male Age Structure and Population Dynamics These age structure diagrams indicate that less developed countries such as Nigeria have a much higher percentage of young people than highly developed countries. As a result, less developed countries are projected to have greater population growth than highly developed countries.