1. Ecosystem Interactions
Lesson 7
September 1st, 2010

2. Biotic Interactions
Organisms in a community interact with one another in many ways. Three main ways are through symbiosis, predation, and competition.

3. Symbiotic Relationships (3 types)
Symbiosis is a close interaction between two different species in which members of one species live in, on, or near members of another species.
1. Commensalism
+ / 0 relationship
One partner benefits without significantly affecting the other
Example – Clown fish and anemone

4. Symbiotic Relationships (3 types)

5. Symbiotic Relationships (3 types)
2. Mutualism
+ / + relationship
Both organisms benefit
Example – Bees and flowers, crocodiles and dikkop birds

6. Symbiotic Relationships (3 types)

7. Symbiotic Relationships (3 types)
3. Parasitism
+/ - relationship
One organism, the parasite, harms the host
Example – Lamprey, tick

8. Symbiotic Relationships (3 types)

9. Predator – Prey Relationships
When one organism consumes a second organism
Example – Lions and Zebras
Some species use mimicry to avoid predators
one species looks like another species.
Monarch butterfly
Viceroy Butterfly

10. Predator – Prey Relationships

11. Competitive Relationships (2 types)
Where organisms compete for an important resource such as food, shelter or possibly mates.
May have negative effects on one another.
Actual fighting or exploitative competition
1. Intraspecific
Between members of the same species
Individuals may compete over food, water, light, space, safe sites, or mates.
Important factor limiting the population size of many species.

12. Competitive Relationships (2 types) 1. Intraspecific

13. Competitive Relationships (2 types) 2. Interspecific
Between 2 or more species
As the population of one species increases, it may limit the density of the competing species

14. Competitive Relationships (2 types) 2. Interspecific

15. page 74 – 76 # 3,4, 6 a-c