1. Species Interactions

2. Predation- when members of one species eat members of another species
Predator (eats) - Prey (is eaten)
What happens to predator population when prey population increases?
What happens to predator population when prey population decreases?

3. C. Symbiosis- 2 or more organisms of different species living together
Mutualism (+/+) both organisms benefit
Sea Anemone on the back of a hermit crab. The anemone adds protection for the crab and the crab gives movement and a better opportunity for food to the anemone.

4. Commensalism (+/0) one organism benefits, the other is unaffected
Clown fish gains protection from predators; anemone gets no benefit
Parasitism (+/-) one organism benefits, the other is harmed
Heart worms benefit and dog is negatively affected

5. Competition (-/-)
the attempt of 2 or more organisms (or species) to use the same resource.
Exploitation competition- tries to use up all of a limited resource to prevent others from using it
2. Interference competition- harms others to prevent them from using a resource.
Organisms always try to avoid competition!

6. How do species avoid competition?
Niche- an organism’s role in an ecosystem.
Only 1 species can occupy a particular niche at a time.

7. Limiting Factors – anything that prevents a population from growing any larger
ex. Any limited resource
Density-independent – population size doesn’t matter. EX: Seasonal climate changes, Natural disasters, and human activity.
Density-dependent – population size does matter. EX: Living space (crowding and stress), disease, competition and predation