Chapter 4

1. Biotic and abiotic factors. 2. The niche 3. Community interactions 4. Ecological succession

 Living factors that influence an ecosystem are called biotic factors. ◦ All the organisms and their interactions.  Nonliving factors that influence an ecosystem are called abiotic factors. ◦ Sunlight, temperature, humidity, average rainfall, soil composition, rock structure…

 How an organism interacts within its environment is called its niche. ◦ What it eats ◦ How it obtains food ◦ When and how it reproduces ◦ If and how it cares for its young ◦ How it modifies its environment  No two species can occupy the same niche.

Bay-Breasted Warbler Feeds in the middle part of the tree Yellow-Rumped Warbler Feeds in the lower part of the tree and at the bases of the middle branches Cape May Warbler Feeds at the tips of branches near the top of the tree Spruce tree Section 4-2 Figure 4-5 Three Species of Warblers and Their Niches

 Organisms interact constantly in their community and help shape the ecosystem. ◦ Competition ◦ Predation ◦ Symbiosis

 Competition ◦ Organisms compete for the same resources.  Water, food, shelter, mates…

 Predation ◦ The interaction when a predator captures and feeds on a prey.

 Symbiosis ◦ Two different species live in close association with each other and at least one benefits.

 Mutualism – both benefit; lichens

 Commensalism – one benefits; shark and remora

 Parasitism- one benefits; one is harmed

 Ecosystems change over time until a climax community is established. ◦ This is called ecological succession.

 Primary succession ◦ Occurs on surfaces where no soil exists. ◦ Bare rock ◦ Lichens and moss.

 Secondary succession occurs when a disaster (natural or man-made) destroys an original community. ◦ Ecosystems tend to return to their climax community unless human activity prohibits this.