1. What Shapes an Ecosystem?

2. Review of Biotic and Abiotic Factors • Ecosystems are influenced by a combination of biological and physical factors. • Biotic factors • include all the living things with which an organism might interact. • Abiotic Factors • Physical, or nonliving, factors that shape ecosystems.

3. Habitat and Niche • Habitat • all aspects of the area in which an organism lives (includes both biotic and abiotic). • Habitats may change or disappear due to natural causes or interference by man.

4. Habitat and Niche • Niche • the role or place and position a species has in its environment. • An ecological niche includes all of the factors that a species needs to survive, stay healthy, and reproduce. • food • abiotic conditions • behavior

5. Habitat and Niche • Why do you think no two species can share the same niche. • One species is better suited to the niche and the other will either be pushed out or become extinct.

6. Community Interactions • When organisms live together in ecological communities, they interact constantly. • Community interactions include: • Competition • Predation • Symbiosis

7. Community Interactions • Competition: • occurs when two organisms fight for thesame limited resource. • Direct competition in nature often results in a winner and a loser—with the losing organism failing to survive.

8. How species avoid Competition • The distribution of these warblers avoids direct competition, because each species feeds in a different part of the tree.

9. Community Interactions Predator • Predation: • occurs when one organism captures and eats another. Prey

10. Community Interactions • Symbiosis: • Any relationship in which two species live closely together • Includes: • mutualism • commensalism • parasitism

11. Community Interactions • Mutualism: • both species benefit from the relationship.

12. Commensalism Human Our eyelashes are home to tiny mites that feast on oil secretions and dead skin. Without harming us, up to 20 mites may be living in one eyelash follicle. Ø Demodicids Eyelash mites find all they need to survive in the tiny follicles of eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope. + Ø + Organism is not affected Organism benefits Community Interactions • Commensalism • one member of the association benefits and the other is neither helped nor harmed.

13. Braconid wasp Braconid larvae feed on their host and release themselves shortly before reaching the pupae stage of development. 0 Parasitism + _ Hornworm caterpillar The host hornworm will eventually die as its organs are consumed by wasp larvae. _ Organism benefits Organism is not affected 0 Community Interactions • Parasitism • one organism lives on or inside another organism and harms it.

14. Ecological Succession • Succession occurs following a disturbance in an ecosystem and regenerates or creates a community after a disturbance. • a sequence of biotic changes • damaged communities are regenerated • new communities arise in previously uninhabited areas

15. Ecological Succession • There are two types of succession. • primary succession — started by pioneer species

16. Ecological Succession • There are two types of succession. • secondary succession — started by remaining species