1. Shaping an Ecosystem

2. Biotic and Abiotic Factors Ecosystems are influences by living and non living Biotic factors: all biological factors in an ecosystem (living) Abiotic: all physical or non living factors in an ecosystem Biotic and Abiotic factors determine the levels of survival and growth of organisms in an ecosystem

3. Community Interactions Community interactions such as competition, predation, and various forms of symbiosis can powerfully affect an ecosystem. Competition: occurs when organisms use the same resources at the same time and the same place.

4. Community Interactions Predation: an interaction when one organism captures and feeds on another organism Symbiosis: means “living together”, any relationship in which two species live closely together Three main classes: mutualism, commensalisms, parasitism

5. Community Interactions Mutualism: Both species benefit from the relationship –Flowers provide insects with food, insects in turn pollinate the flowers Commensalism: one member of the association is helped, and the other one is neither helped nor harmed. –Barnacles on a whale, do not hurt the whale, but the movement through water brings them food

6. Community Interactions Parasitism: one organism lives on or in another organism and harms it. –Parasites generally weaken, but do not kill their host –Tapeworm, fleas, ticks, lice.

7. Ecological Succession Ecosystems are constantly changing in response to natural and human disturbances Ecological succession: a series of predictable changes that happen over time

8. Ecological Succession Primary succession: successions that occur on land where no soil exists The first species to populate an area is called a pioneer species –Lichens are often a pioneer species as they help break up rock

9. Ecological Succession Secondary Succession: after a disturbance such as fire or farming, an ecosystem attempts to return to its original state Succession is a natural process: some plants are so adapted to forest fires, they will not drop their seeds unless exposed to high heat. Ecosystems cannot always recover from large human disturbances