1. What kind of plants do we see in a climax community?
Agenda for Tuesday Jan 27th
Population Notes

2. Why study populations?
Learn how organisms change over time, problems in an environment, and relationships between organisms

3. Population Growth Rate
Must know birthrate and mortality
Emigration – moving out of a pop.
Immigration – moving into a pop.
Immigration rate = emigration rate
Calculating growth rate
=(population at end – population at beginning)
Population at beginning

4. Exponential Growth Rate
Occurs when organisms have ideal conditions
More individuals = faster growth
Rarely happens
WHY?
Limiting factors

5. Logistical Growth Rate
Steady state
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
Slows
Lag
Exponential

6. 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?

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

8. Limiting Factors…
Anything that prevents the number, reproduction, distribution, growth of an organism
Abiotic
Biotic

9. Tolerance – ability of an organism to survive when subjected to limiting factors
Upper and lower limit = range

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

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

12. 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)

13. 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

14. 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.

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

16. Dispersion Pattern: Uniform

17. Dispersion Pattern: Clumped

18. Dispersion Pattern: Random

20. Reproductive strategies
R-strategy (rate strategists)
Produce as many offspring as possible in a short time
Little energy in raising young
K-strategists (carrying capacity strategy)
Few offspring that have a better chance of living
Expend a lot of energy raising young

21. Compare and contrast r and k reproductive strategies
Agenda for Wednesday Jan 28th 1. Invasive species project Quiz tomorrow

22. What is a density independent factor? A density dependent factor?
Agenda for Thursday Jan 29th
Go over HW
Quiz
Human populations

23. 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

24. Human Population Growth

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

26. Resource Consumption (6)
High consumption
Getting worse
Rate increase faster than population growth

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

28. 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…..

29. Biodiversity is in Danger
Humanity has spawned a species extinction to rival the 5 great extinctions of million years ago
Recovery times from the great extinctions 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

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+)

32. Why do some countries have a growing population while other countries have a declining population?

33. Concept Web Social, economic, envt
Positive, neutral, neg impacts on more people

34. What event in human history helped spark our population growth?
Agenda for Friday jan 31st
Quiz
Present

35. What concerns are there about the increase in human population?
Agenda for Monday Feb 3rd
Present
Biomes