1. Interactions of Organisms

2. Make two lists: Living and Nonliving

3. What is Ecology?
Study of interactions between organisms and their environments
Many factors affect the interactions of organisms:
Abiotic Factors (nonliving factors)—water, temperature, light, nutrients
Biotic Factors (living factors)—other organisms living in the same environment

4. 4 Levels of Ecological Study
Population
Group of individuals of the same species living in a particular area
Community
All the organisms living in a particular area
Ecosystem
A community along with all abiotic (nonliving) factors in a particular area
Biome
Major terrestrial area and their ecosystem

5. Example of organization…
Population
Coyote Population
Community
All the organisms living in the desert
(coyotes, snakes, cacti, sage brush, hawks, etc)
Ecosystem
community + the abiotic factors (water, air, soil, etc)
Biome
The complete Desert Biome

6. Size of a Population Size can be affected by:
Birth Rate (natality)
Death Rate (mortality)
Immigration: movement into an area
Emigration: movement out of an area
Stable Population…population with no overall growth
Births + Immigration = Deaths + Emigration

7. Name two factors that can cause a population to grow.
What is the difference between emigration and immigration?
What term is used to represent all the living organisms in an area?
What is meant by abiotic factors?

8. Interactions Within a Community
Competition
Predation
Symbiosis

9. Competition Competing for… Interspecies Competition
Food, water, shelter, homes, space
Interspecies Competition
Competition BETWEEN different species
Intraspecies Competition
Competition WITHIN the same species

10. Predation: Predator-Prey Interaction
Interaction between species when one organism is the resource (food) of the other
What is it?
The size of the population of each is dependent on the other
Lots of prey….increase in predators
Lots of predators…..decrease in prey

11. Symbiosis Interaction of two organisms living together
Mutualism
Both Benefit
Commensalism
One benefits—One unaffected
Parasitism
One benefits—One harmed

12. 1. Mutualism Both organisms benefit from the interaction Examples:
Flowering plants & Insects
Nitrogen-fixing Bacteria & Legume plants

13. 2. Commensalism
An interaction when one benefits while the other is neither harmed nor benefited
Usually physical attachment of the benefiting organism to the other (host)
Barnacles & Sea Animals
Protection
Food Source
Tropical Fish & Sea Anenomes
Protection
Not affected by the stinging tentacles of the sea anenome

14. 3. Parasitism
An interaction when one benefits while the other is harmed
Benefiting organism: parasite
Harmed organism: host
Examples:
Lice
Tapeworms