1. 5/9/12
Objective: Understand the levels of ecological organization and how energy flows through an ecosystem
Warm-Up: Describe one way that species might interact in an ecosystem

2. Ecology Vocabulary
Ecology—the study of the interactions among organisms and their environment
Environment—all of the living and non-living factors in an organism’s surroundings
Biotic Factors—living things in an organism’s environment
Examples: plants, fungi, bacteria, etc
Abiotic factors—nonliving things in an organism’s environment
Examples: temperature, water, sunlight, climate, soil, etc

3. Ecological Organization
Organism—the smallest unit of ecological study; one specific living thing
Population—a group of organisms of the same species living in the same place at the same time
Community—all of the populations in a particular location

4. Ecological Organization
Ecosystem—all of the communities and all of the abiotic factors within a particular area
Emphasizes interactions between different populations and the abiotic environment
Biosphere—all of Earth’s ecosystems

5. Biosphere
Ecosystem
Community
Population
Organism

6. Niche and Adaptation
An organism’s niche can be defined as how it makes a living in its ecosystem—different organisms are adapted to use different resources/habitats in an ecosystem
For example: the niche of an earthworm is to break down organic matter in the soil.
Organisms can reduce competition by specializing in a particular niche

7. Niche and Biodiversity
Biodiversity is a measure of how many different species are found in a particular area
Ecosystems with higher biodiversity tend to have fewer “empty niches,” meaning that more of their resources are being taken advantage of by organisms
As a result, higher biodiversity generally results in more productive ecosystems
What is the relationship between natural selection/adaptation and niches?

10. In your notes, create a food web using the following organisms:
Rabbit Hawk (carnivorre)
Deer Mouse
Mountain Lion Shrubs (produces leaves and berries)
Grass Squirrel
Grasshopper Oak tree
Snake Robin (eats insects, berries)

11. 5/10/12 Objective: Understand energy flow in an ecosystem
Warm-Up: What determines a biome?

12. Trophic Levels “Trophic” comes from the Greek word for energy
Organisms in an ecosystem can be classified into different trophic levels based on how they obtain their energy
Producers (autotrophs): obtain energy from inorganic sources (photosynthesis, chemosynthesis)
Always at the base of the food web
They bring energy into an ecosystem
Plants (terrestrial ecosystems), bacteria (terrestrial/aquatic), phytoplankton/algae (aquatic)

13. Trophic Levels…
Primary Consumers: herbivores; organisms that feed on producers
Secondary Consumers (omnivores/carnivores): feed on primary consumers/producers
Tertiary Consumers (carnivores): feed on secondary/primary consumers
Quaternary consumers (carnivores): feed on tertiary/secondary/primary consumers
All consumers are heterotrophs

14. Trophic Levels…
Decomposers are generally placed in a category separate from consumers
They are heterotrophic organisms who get their energy from breaking down dead organic matter
Earthworms, fungi, bacteria: these organisms not only get energy from organic waste, they participate in nutrient recycling
Scavengers (i.e., vultures, hyenas) are not the same as decomposers

15. Given…
One mountain lion eats approximately 1,125 pounds of venison each year as well as numerous smaller animals. However, the mountain lion will eat only 50% of each deer he/she kills.
One deer averages 150 lbs in weight
One deer eats approximately 3,650 pounds of vegetation each year in the form of grasses, nuts and berries.
One square mile of deer habitat produces 760 pounds of deer food each year.
How many deer does a mountain lion need to eat in a year?
How much land is needed to support one deer for a year?
How much land is needed to support one mountain lion for a year?

17. Food Webs, Trophic Levels, and the Energy Pyramid
Sort the organisms from your food web into an energy pyramid and consider the following questions: Which population will be larger in this ecosystem— grasshoppers or mountain lions? Why? Which level of the pyramid has the highest amount of available energy?

18. The 10% Rule: In an ecosystem, only 10% of the available energy in one trophic level gets transferred to the next trophic level

21. Species Interactions Competition
Organisms in an ecosystem compete for limited resources
Interspecific competition occurs between two individuals from different species (ex: squirrels and chipmunks compete for acorns)
Intraspecific competition occurs between two individuals of the same species (ex: two young oak trees compete for light)

22. Species Interactions Predation: predator eats prey
Symbiosis: broad term referring to organisms from different species living together
There are three different categories of symbiosis
Mutualism (+/+): a relationship in which both of the organisms involved have a fitness benefit from the interaction
Example: Ants and acacia trees The ants live in the thorns of the tree, live off of the tree’s nectar, and attack herbivores

23. Symbiosis…
Commensalism (+/0): a symbiotic relationship in which one organism gains a fitness benefit and the other organism is unaffected
Ex: Egrets (birds) and cattle (cows) As cows move and graze, they disturb insects. Egrets follow the cows and feed on the insects.
Parasitism (+/-): a symbiotic relationship in which one organism gains a fitness benefit by harming another organism
Ex: Leeches and mammals A leech will attach itself to a mammal’s skin and take blood from the mammal.

24. Chemical Cycles in Ecosystems
Matter is not created or destroyed, just converted into different forms and recycled!
Within ecosystems, chemical compounds cycle in predictable ways
“Sources” refer to locations/organisms/processes that produce a particular compound
Ex: cellular respiration is a source of carbon dioxide
“Sinks” or “reservoirs” refer to locations/organisms/processes that store a particular compound
Ex: Polar ice caps are reservoirs of fresh water

25. The Hydrologic Cycle (Water Cycle)

26. The Carbon Cycle

27. The Nitrogen Cycle

28. The Nitrogen Cycle Organisms need nitrogen to build proteins
Atmospheric nitrogen (free nitrogen), N2, cannot be used directly by most organisms
Some species of bacteria “fix” nitrogen into compounds that can be used by plants
Some of these nitrogen-fixing bacteria live in the root system of some plants in a mutualistic relationship
There are also denitrifying bacteria; these microorganisms convert nitrogen compounds into free nitrogen