1. Chapter 8 Population Change

2. Do Now What is Population Ecology?
What are some Principles of Population Ecology?

3. Principles of Population Ecology
Deals with the number of individuals of a particular species that are found in an area & how & why those numbers change over time.
Used in Forestry, agriculture, animal husbandry, and wildlife management.

4. Principles of Population Ecology
Population ecologists ask:
1) How many are in the population?
2) Are its numbers increasing / decreasing?
3) What is its pattern of reproduction?
4) What is its pattern of mortality?

5. Principles of Population Ecology
Population Density:
Not enough to know just how many.
Need to know per unit area.
20 / 100 m2
20 / 25 m2

6. Do Now: Principles of Population Ecology
How have immigration and emigration affected your local population?
HINT: consider impacts on education (K-postsecondary), housing, transportation, the workforce, social services, the local economy, and the local political climate,

7. Principles of Population Ecology
How Do Populations Change in Size?
On a global scale (closed system):

8. Principles of Population Ecology
How Do Populations Change in Size?
On a local scale (open system):

9. Principles of Population Ecology
How Do Populations Change in Size?
Global scale:
Death rate
Growth rate
r = b – d
Birth rate

10. Principles of Population Ecology
How Do Populations Change in Size?
Local scale:
Death rate
Growth rate
Emigration rate
r = (b – d) + (i – e)
Birth rate
Immigration rate

11. Hypothesize: : Your employer makes you this offer, Would you rather make:
0.01¢ a day that grows exponentially for 30 days
$75 an hour working 30 days 8 hours a day?

12. Hypothesize: Your employer makes you this offer, Would you rather make:
0.01¢ a day that grows exponentially for 30 days
$75 an hour working 30 days 8 hours a day?
$75/hour x 8 hours= $600/day x 30days = $18,000/30days

13. Hypothesize: Your employer makes you this offer, Would you rather make:
0.01¢ a day that grows exponentially for 30 days
Day $
Day $
,088.64
1,342,177.28
2,684,354
$5,368,709.12

14. Principles of Population Ecology
Maximum Population Growth-
under ideal conditions = intrinsic rate of increase (aka biotic potential)
J-shaped curve (exponential growth)

15. Do Now: Principles of Population Ecology
Explain why cockroach populations will not
expand indefinitely and take over the entire
world.
Include in your discussion appropriate
definitions of population growth terminology
such as: exponential growth, logistic
growth, carrying capacity, and resistant
factors.

16. Do Now: ANSWERS Principles of Population Ecology
Cockroaches populations exhibit exponential growth, that is accelerating population growth that occurs when optimal conditions allow a constant reproductive rate over a period of time.
When the cockroach population grows exponentially, the larger the population gets, the faster it grows (J curve).
However, environment resistance factors limit growth of the population.
These factors include such unfavorable environmental conditions as the limited availability of food, water, shelter, and other essential resources (resulting in increased competition) as well as limits imposed by disease and predation.
As the number of individuals in a population increases, so does environmental resistance, which acts to limit population growth. Because the environment sets limits, cockroach population growth is transformed from exponential growth into logistic growth.
In the logistic growth pattern, the population of roaches would level at the carrying capacity appropriate for the local environment. The carrying capacity is the maximum number of individual of a given species that a particular environment can support for an indefinite period, assuming thee are no changes in the environment.

17. Principles of Population Ecology
Environmental Resistance-
Exponential growth cannot occur forever.
The larger the population the faster it ____ ?
What factors prevent it from doing so?
Grows
S-shaped curve (logistic growth)

18. Principles of Population Ecology
Overshooting the carrying capacity can lead to a population crash.

19. Do Now: Reproductive Strategies
Please provide the 2 Life History Strategies.
List the their characteristics.

20. Do Now: Answers Reproductive Strategies
Life History Strategies
r-selected
K-selected
vs.
high growth rate
slow growth rate
small body size
large body size
early maturity
late maturity
short life span
long life span
large broods
small broods
little / no parental care
high parental care

21. Reproductive Strategies
Survivorship

22. Do Now: Reproductive Strategies
Identify the two most extreme types of reproductive strategies and make a distinction between the traits that would characterize these extremes.
Give an example of an organism that illustrates each strategy.

23. Do Now: Answers Reproductive Strategies
Populations described by r selection have traits that contribute to a high population growth rate.
Weeds, such as dandelions, and insects, such as mosquitoes, are examples of “r” strategists.
Distinguishing traits typical of r strategists include: small body size, early maturity, short life spans, large broods and little or no parental care of offspring.
These organisms live in unpredictable environments where the probability of long-term survival is low.
In populations described by K selection, traits maximize the chance of surviving in an environment where the number of individuals is near the carrying capacity of the environment.
Characteristics of K strategists include: long life spans with slow development, delayed reproduction, large body size, and a low reproductive rate with high parental obligations to offspring.
Tawny Owls, humans, elephants, and redwood trees are all examples of the “K” strategists.

24. Do Now: Principles of Population Ecology
Describe an example of a density- dependent and independent population factor.

25. Do Now: ANSWER Principles of Population Ecology
Describe an example of a density- dependent and independent population factor.
density-independent factors impact populations uniformly no matter the population density
these are usually abiotic, “natural disaster” phenomena such as freezes, heat waves, droughts, floods, severe fires or hurricanes
density dependent factors are those that influence low density populations differently from high density populations
d-d factors influence population growth by decreasing birth rates and / or increasing death rates
d-d factors include such things as disease, predation and / or competition for any resource necessary for that population
the impact of d-d factors is difficult to assess in a wild population because of the many variables that affect population growth

26. Factors that Affect Population Size
Density-Dependent Factors-
Factors that influence population growth when its density is high.
Predation, competition, disease.

27. Factors that Affect Population Size
Density-Independent Factors-
Regardless of population density, influences population growth.
Weather, fire.

28. Factors that Affect Population Size
Density-Dependence and Boom-or-Bust Population Cycles

29. Do Now: ANSWERS
Who was Thomas Malthus and what were his ideas about human population growth? Was he correct or not? Justify your answer.

30. Do Now: ANSWERS
Thomas Malthus was a 19th century British economist who was one of the first people to recognize that the human population cannot increase indefinitely.
He correctly pointed out human population growth is not always desirable because it can exceed the food supply resulting in famine, disease and war. Since Mathus’s time, the human population has increased from 1 to 6 billion.
Scientific advances have allowed food production to keep pace with population growth. Malthus may ultimately be correct in his ideas because we do not know if our increase in food production is sustainable.

31. Factors that Affect Population Size
Case-in-Point: Predatory Prey Dynamics on Isle Royale

32. Do Now: Factors that Affect Population Size
Discuss the factors that have regulated the moose population on Isle Royale. Your discussion should include the following terms: Predator-prey dynamics, density dependence, density independent factors.

33. Do Now: ANSWER Factors that Affect Population Size
On the island of Isle Royale, the moose population is preyed on by wolves. Prior to the introduction of predators on Isle Royale, the moose population was controlled by the supply of vegetation and viral diseases, which are both density dependent factors.
In addition, the density independent factor of severe winters killed the old and the young moose alike. When wolves were introduced, the predator – prey dynamics between the wolf and moose populations became the primary regulating factor of the moose population.

34. Factors that Affect Population Size
Case-in-Point: Predatory Prey Dynamics on Isle Royale

35. Factors that Affect Population Size
Case-in-Point: Predatory Prey Dynamics on Isle Royale

36. Factors that Affect Population Size
East end of island
West end of island

37. Factors that Affect Population Size
example of small annual growth
example of large annual growth

38. Factors that Affect Population Size

39. Factors that Affect Population Size

40. The Human Population
Human population size

41. The Human Population Current Population Numbers In 2004 = ~6.4 billion
Check out:

42. Question about Human Population
The world population increased by 82 million from Why has this occurred if the birth rate has declined during the past 200 years?

43. Question: ANSWER about Human Population
Due to advances in modern medical technologies; Vaccines, antibiotics, advances in medical facilities has led to a dramatic decrease in death rates.

44. The Human Population Current Population Numbers
Rapid growth primarily due to drop in death rates

45. The Human Population Projecting Future Population Numbers
When will zero population growth occur?

46. Do Now: Demographics of Countries
Describe at least three factors that determine whether a nation is classified as a developed or developing country?

47. Do Now: Answers Demographics of Countries
Describe at least three factors that determine whether a nation is classified as a developed or developing country?
life expectancy
health care system
educational system, esp. opportunities for women
amount of infrastructure
global vs local market economy
use of technology
degree of industrialization
standard of living
literacy rate
birth rate
death rate, esp. infant mortality rate
per capita GDP
degree of urbanization

48. Demographics of Countries
Most Populous Countries
Insert Table 8.1

49. Demographics of Countries
Developed vs. Developing Countries Demographics
Insert Table 8.2 (note reconstruction)

50. Demographics of Countries
Developed vs. Developing Countries Demographics
Insert Table 8.2 (note reconstruction)

51. Question: Demographic Stages???
To date, all highly developed and moderately developed countries with more advanced economies have gone through a progress or demographic transition.
Describe the four steps in this process in terms of the impact birth and death rates have on population growth.

52. Question: ANSWER Demographic Stages???
As countries become industrialized and urbanized, they go from having relative high birth and death rates to having relatively low birth and death rates.
There are four stages in this process:
the pre-industrial stage in which birth and death rates are high and the population grows at a modest rate. Famine plagues
Then as a result of improved heath care, better food and water supplies, the population enters the transitional stage characterized by a lower death rate. The population grows rapidly because the birth rate is still high. Increased water quality and reliable food production
3.The third demographic stage is the industrial stage characterized by a decline in birth rate, which slows the population growth despite a relative low death rate.
4.Finally, low birth and death rates characterized the last stage. This is the post industrial stage when people are better educated and more affluent and the population grows slowly or not at all in this stage. increased focus on education and smaller families

53. Demographics of Countries
Demographic Stages

54. Demographics of Countries
Age Structure of Countries
Generalized Age Structure

55. Demographics of Countries
Examples:

56. Do Now: Demographics of the US
How does the population growth of the United States compare to that of other countries, both highly developed and developing?
What factor(s) may account for the unique aspects of population growth seen in the U.S.?

57. Do Now:ANSWERS Demographics of the US
The U.S. has the largest population of all highly developed countries and one of the highest rates of population increase.
U.S. citizens have a high level of material well being compared to the global population.
Highly developed countries, such as the U.S. have the lowest birth rates in the world as well as low infant mortality rates. However, the unique aspect of population growth seen in the U.S. stems from immigration (authorized and unauthorized).
Immigration has a greater effect on population size in the U.S. than in other nations as more people from developing countries immigrate to the U.S. for a better life.

58. Demographics of Countries
Examples:

59. Demographics of Countries
Examples:

60. Demographics of Countries
Population Under Age 15:

61. Do Now: Demographics of the US
What is the environmental issue regarding current immigration policy in the U.S. and why is this issue controversial?

62. Do Now: Answers Demographics of the US
Adding immigrants (authorized and unauthorized) to the population of the U.S., given our current rate of consumption of resources has a global environmental impact.
The issue centers on allowing large number of immigrants to enter the U.S. without consideration for the altered forces placed on resource consumption.
The U.S. has space and room for more people, but the U.S. lifestyle is such that we are using between 6-50 times the resources of other countries per person.
The larger U.S. population contributes to pollution and resource depletion.

63. Demographics of the US
Case-in-Point: US Immigration

64. Demographics of the US