1. Ecology: Everything Else 

2. Communities
(From 4/23) A group of interacting populations that occupy the same area at the same time.
Living things only
Organisms adapt to the conditions under which they live.
What factors might influence tropical fish community?

3. Limiting Factors and Tolerance
A limiting factor restricts the…of organisms
Number
Reproduction
Distribution
Could be biotic (e.g. competition for food) or abiotic (e.g. temperature)
Range of tolerance – upper and lower limit of a particular limiting factor
Example: steelhead trout live in a temperature range of 9-25 °C
Conditions under which they can live (might not necessary thrive)

4. Ecological Succession
How might an ecosystem respond to a drastic change in biotic/abiotic factors?
Example: forest fire

5. Primary Succession
The establishment of a community in an area of exposed rock that does not have any topsoil
Example: Solidified lava flow
First step: Lichens (a mutualistic relationship between a fungus and an algae) and mosses
As they die, they make first layer of soil
Example of a Pioneer species
Later: weedy plants (grasses and ferns)
Much later: shrubs and trees

7. Secondary Succession
A process that occurs after a disturbance has taken place, but the soil remains
Example: forest fires
What’s different about the time scale?
Thought question: notice the species at the start and at the finish

8. When does succession “end?”
Unclear. (hard to tell)
Climax community – when a stable community has formed
What role
might humans
play?

9. Population Ecology Chapter 5

10. Species Occur in Groups Called Populations
Population density – the number of organisms per unit area
Species distribution (dispersion patterns)
Based on the availability of resources (food)
Examples in the notes section of PowerPoint
Pattern of spacing within an area (based on the organism’s needs). Examples
Clumped – American bison
Uniform – black bears
Random – White-tailed deer

11. Population-limiting Factors
Both of these types control population numbers, but in different ways
Density-independent factors – do not depend on the number of organisms per unit area
Abiotic factors – weather events like drought, flooding, extreme temperature, or tornadoes
Forest fires – crown v. controlled fires

13. Density-dependent factors
Any factor that depends on the number of members per unit area
Usually biotic factors
Disease – outbreaks occur when population density is high
Parasites – can limit the population size when population density is high
Competition – increases when population density is high

14. Lemmings – Competition
Population grows exponentially until food become limited and the population sizes decreases significantly

15. Population Growth
Population growth rate explains how fast a population grows
Birth rate
Death rate
Emigration – moving away from a population
Immigration – moving into a population

16. Exponential Growth – J-Shaped
No limits placed on a population by its environment
Numbers
Time

17. Logistic Growth – S-shaped
Most populations
Growth slows when the carrying capacity is approached
The maximum number of individuals that an environment can support in the long-term
Determined by energy, water, oxygen, and nutrients available

19. Reproductive Patterns
r-strategy – resources fluctuate
Carrying capacity varies
Produce as many organisms as possible to take advantage when resources are high
Insects
k-strategy – resources are constant
Carrying capacity is constant
Produce only a few offspring that have a better chance of surviving
Large mammals

20. Human Populations
Click the link below for a quick video on human population!

21. Demography
Study of human population size, density, distribution, movement, and birth/death rates
Why is the human population increasing more
rapidly now than
it did in the past?
Technological
advances
Modern
medicine

22. Age Structure in Human Populations
Number of individuals in age groups
No or negative growth. Think about why these different countries would have different kinds of growth!

23. Human Carrying Capacity
Can we increase our carrying capacity forever?
How much time do we have?
Population ecologists predict a global population of 8.110.6 billion people in 2050
Estimate – billion
How can we manage the use of our resources? Sustainability! (look it up)

24. Biodiversity and Conservation
Chapter 5

25. Biodiversity
Variety of life as determined by the number of different species in a given area
Three types
Genetic diversity – variety of genes or inheritable characteristics
Species diversity – number and abundance of different species in a community
Ecosystem diversity – variety of ecosystems in the biosphere

26. Genetic diversity in a vole population
Species diversity in a coastal redwood ecosystem
Community and ecosystem diversity across the landscape of an entire region

27. Why is Biodiversity Important?
Direct economic value – food, energy, clothing, energy, medicine, and shelter.
Indirect economic value – green plants provide oxygen, cycles provide clean drinking water (New York City, 1990)
Aesthetic and scientific value
6 billlion on water filtration, or 1.5 billion on cleaning up watersheds!