1. How would you describe a relationship between a tick and a dog? Why?
Objectives:
SWBAT distinguish between the different types of symbiotic relationships.
SWBAT explain the importance of symbiotic relationships in population control.
Do Now:
How would you describe a relationship between a tick and a dog? Why?
How would you describe a relationship between a human and a dog? Why?
Agenda:
Species Interactions
Ecosystem Simulation
Life’s Work:
Read chapter 2 and study for quiz on Tuesday

2. How Do Species Interact?
Symbiosis: interaction between 2 or more species
Predation
Competition
Parasitism
Mutualism
Commensalism

3. Parasitism:
when one species (parasite) feeds on part of another species (host) by living on or in it

4. Although parasites can harm their hosts, they can promote community biodiversity.
Some parasites live inside host (micro-organisms, tapeworms)
Some parasites live outside host (fleas, ticks, mistletoe, sea lampreys)
Some have little contact with host (dump-nesting birds like cowbirds, some duck species)

5. when both species benefit
Mutualism:
when both species benefit

6. when one species benefits without harming or benefiting the other
Commensalism:
when one species benefits without harming or benefiting the other

7. when one species (predator) feeds off of another (prey)
Predation:
when one species (predator) feeds off of another (prey)

8. The predator and prey cycle, when graphed, is often called a “Sawtooth Curve.”

9. Why is predation important?
Predators usually kill the sick, weak or aged.
Genetic stock is improved because the weaker animals are killed first.
The surviving prey get greater access to limited resources.

10. when two or more species compete for limited resources
Competition:
when two or more species compete for limited resources

11. Factors That Affect Competition
Increasing Competition
Anything that increases the population, because the more organisms there are, the scarcer the resources
Examples: increased birth rates, decreased death rates, increased food supply
Decreasing Competition
Anything that decreases the population, because the fewer organisms there are, the greater the resources
Examples: increased death rate (from temperature, drought, disease, predators, etc.)

12. Your Turn
Watch the following video clips and classify the type of relationship between the species.