1. What is a population? Agenda for Monday Jan 30th Populations notes
Population worksheet

2. Basic characteristics of a population:
Why study populations?
Learn how organisms change over time, problems in an environment, and relationships between organisms
Population has group and not individual characteristics
Basic characteristics of a population:
Density (no/area; no/vol)
Size (numbers)
Age Structure (based on age distribution)
Dispersion (the spread of individuals in relation to one another)

3. What causes populations to change?
Birth Rate
Death Rate
Number of individuals that enter and/or leave
Immigration – into
Emigration – out
(Birth rate + immigration) – (death rate + emmigration)

4. Survivorship Curves

5. Exponential Growth Rate
Ideal conditions
More individuals = faster growth
Rarely happens
WHY?
Limiting factors

6. Logistical Growth Rate
Populations go through different growth phases
Lag Phase – slow growth
Exponential growth – rapid growth, few die, many reproduce
Population growth slows down
Steady state – population levels, birth rate = death rate

7. Carrying Capacity
Maximum number of individuals that an environment can support
Measured in winter

8. Questions
The human population is currently growing at an exponential rate. What does this mean about our birth and death rates?
The Mantled Howler Monkey is currently considered an endangered species. What does this mean about its birth and death rates?

9. Population Density # of organisms per area
Dispersion – pattern of spacing of populations
3 types
Uniform
Clumped
Random

10. Dispersion Pattern: Uniform

11. Dispersion Pattern: Clumped

12. Dispersion Pattern: Random

14. Population Ranges Species are limited to where they may exist
Abiotic conditions
Temperature Humidity
Rainfall Sunlight
Biotic conditions
Predators
Competitors
parasites

15. Limiting Factors…
Tolerance – ability of an organism to survive when subjected to limiting factors
Upper and lower limit = range

16. Density independent factors
affects the size of a population regardless of the population density
Abiotic
Weather, Water, Fire, Sunlight, temperature
Humans – dams, pollution

17. Density Dependent Factors
A factor whose effects on the size or growth of population vary with the population density
Biotic factors
Predation, disease/parasites, competition
Food, water, shelter (resources)

18. Disease/Parasites
Outbreaks of disease tend to occur when population size has increased
Disease is transmitted faster
True for humans as well as animals
Parasites increase at higher densities

19. Questions
Imagine a population of skunks. Imagine that the skunks are reproducing at a very high rate, and the skunk population is growing rapidly. a) List a possible density-independent factor that could stop the skunk population’s growth. b) List a possible density-dependent factor that would limit the skunk population’s growth.

20. Reproductive strategies
R-strategy (rate strategists)
Reproduce quickly with many offspring
Little energy in raising young
Short life span
Small in size
K-strategists (carrying capacity strategy)
Few offspring
Expend a lot of energy raising young
Long life span
Larger organisms

22. Human Population Growth
It took all of human history up to the early 1800s for world population to reach 1 billion people
until 1960 to reach 3 billion
Today, the world gains 1 billion people every 11 years
The current population is almost 8.5 times larger than the population of 760 million at the beginning of the Industrial Revolution
At current growth rates, the world population could double in as little as 58 years

27. What’s Behind Population Growth
Animal Domestication and Agriculture
Provided for a few to feed many
Industrial Revolution
Growth of Cities and Infrastructure
Water
Energy
Transportation
Increased Productivity
Nutrition
Sanitation
Medicine
Leads to
Increased Fertility
Lower Infant Mortality
Increased Longevity

28. Human Carrying Capacity
Technology has allowed us to raise Earth’s carrying capacity
Tool-making, agriculture, and industrialization each enabled humans to sustain greater populations

30. Human Population Growth
Zero population growth
birth rate + immigration rate = death rate + emigration rate
Age structure
# of males and females in three age groups
Pre-reproductive (0-19), reproductive (20-44), and
post –reproductive (45-80+)

31. Having many individuals in young age groups results in high reproduction and rapid population growth

32. Why do some countries have a growing population while other countries have a declining population?
Male
Female
Expanding Rapidly Guatemala
Nigeria
Saudi Arabia
Expanding Slowly United States Australia
China
Stable
Japan
Italy
Greece
Declining
Germany
Bulgaria
Russia
Prereproductive ages
0–14
Reproductive ages
15–44
Postreproductive ages
45–85+

33. Four Stages of Demographic Transition

34. Water consumption
Carbon emissions

35. Resource Consumption

36. Our ‘Commons’ are in Danger
Atmospheric pollution and climate change
Water pollution, including ground aquifers
Deforestation and loss of oxygenation
The oceans, coral reefs and their bounty
National parks, wildernesses and wetlands
Nonrenewable natural resource depletion
Fossil fuels, mineral ores, topsoil…..

37. Biodiversity is in Danger
Humanity has spawned a species extinction to rival the 5 great extinctions
Recovery times took 10’s of millions of years
Biodiversity is essential to life on Earth and holds untold treasures for the future
An ecological ethic is emerging

38. Concept Web write the “7 Billion People and Growing” in the middle
draw arrows to any of the other concepts that form a cause and effect relationship
Social, economic, envt impacts
Positive, neutral, neg impacts on more people

40. Why do developing countries have a growing population while developed countries have a stable population?
Agenda for Friday Nov 4th
Population questions
Go over populations worksheet
Biodiversity

41. Quick Questions What is a density independent factor?
List 1 example
What is a density dependent factor?
Why do populations rarely exhibit an exponential growth rate?
When populations level out in logistical growth rate, what is it called when they level out?
5. A population is at carrying capacity. What does that mean about its birth rates and death rates?

42. 6. The Mantled Howler Monkey is currently considered an endangered species. What does this mean about its birth and death rates? 7. What are some limiting factors that would put a population at its carrying capacity? 8. What type of growth are humans experiencing? 9. What major factors (3) have contributed to human population growth? 10. What is a characteristic of an r-strategy reproducing organism?