1. Intro to Ecology

2. What is ecology?
the study of the interactions between living things and their environment

3. Ecology-related terms:
Biology - the study of how and why living things work
Ecosystem - all the parts that make up a biological community and its environment

4. All living things require some form of energy to survive
Life forms use energy to create the materials (building blocks) and food that they need
If the energy source runs outcan’t make/get the food it needs life form dies

5. Virtually all life on Earth gets its energy
from the light energy of the sun
The sun burns Hydrogen in a process called fusion
Some life forms on Earth can use this energy directly to make food (ie. Plants)
Some life forms on Earth can use this energy indirectly by eating other organisms (ie. Animals)
The relationships between the organisms that harness the suns energy is analyzed when studying trophic levels

6. Trophic Levels
A trophic level represents a specific level of a food chain
a series of organisms that show predator – prey relationships
We will look at 4 distinct levels

7. Producers (1st level) ‘bottom’ of the food chain
can use energy from the sun directly
they can make the food they need

8. Consumers (2nd-4th levels)
get energy from what it eats
Fall into 1 of 3 levels:
Primary consumers - eat plants
Ex. Herbivores
Secondary consumers - eat small animals
Ex. Small carnivores
Tertiary consumers - eat larger animals, ‘top’ of the food chain
Ex. Large carnivores

9. ‘Kinds’ of Consumers Herbivore: an organism that eats only plants
Ex. Caterpillars
Carnivore:
an organism that eats only animals
Ex. A robin
Omnivore:
an organism that eats both plants and animals
Ex. Human Beings

10. an organism that consumes any remaining dead plant and animal matter
Detritivore:
an organism that eats the bodies of smaller dead animals, dead plant matter and animal dung
Ex. Earthworms
Decomposer:
an organism that consumes any remaining dead plant and animal matter
Ex. Fungi (Mushrooms)
Ex. Bacteria

13. Trophic Cascades
Trophic cascades occur when predators in a food web suppress the abundance or alter the behavior of their prey, thereby releasing the next lower trophic level from predation (or herbivory if the intermediate trophic level is a herbivore).

16. How Wolves Change Rivers

17. Types of Pyramids

18. Pyramid of Numbers
A simple idea that describes why some organisms are rare while others are very common
Can be explained looking at trophic levels:
Big animals eat small animals
The number of small animals available limits the number of big animals that can survive
Small animals eat herbivores
The number of herbivores available limits the number of small animals that can survive (etc, etc)

19. There are (usually) more organisms at lower levels of the food chain than the higher up.
Question: Can you think of an example when this isn’t the case?

20. Pyramid of Biomass
Refers to how much (mass) of a particular organism is available
In a defined area the biomass of producers is (usually) greater than the biomass of primary consumers
The biomass of primary consumers is (usually) greater than the biomass of the secondary consumers
This trend continues as you move up the food chain

22. Pyramid of Energy Flow Energy can be stored in an organism
Ex. Like a battery that stores electrical energy
Most of the energy that is stored in an organism is located in body tissue
When an organism (higher on the food chain) eats another organism (lower on the food chain) the amount of energy transferred to the next trophic level is between 5 – 20%
This means that 80-95% of the stored energy is lost
Most is lost as waste
Some is lost as heat

23. When you eat something, only around 10% of the energy available is used by your body
This fact reveals the pyramid of energy flow
The chemical energy available decreases as the trophic level increases
Explains why most food chains have only 4 links