1. 4-2 Niches and Community Interactions

2. The Niche Niche – Where and How something lives; its role
Habitat is the organism’s address
Niche is the organism’s occupation

3. Community Interactions
Competition
Organisms compete for resources
Ex: Food, Mates, Shelter
Competitive Exclusion Principle – no 2 organisms occupy same niche at same time.
Predation
One organism (predator) captures and feeds on another (prey).
Battle at Kruger Lake

4. Community Interactions
Symbiosis
Mutualism – both benefit
Ex: Flowers & insects
Egrets & Alligators
Clown Fish & Sea Anemone
Commensalism – one benefits, the other is not helped nor harmed
Ex: Barnacle & Whale
Parasitism – one benefits, other is harmed
Ex: tapeworms, fleas, ticks, lice

5. Otters and Kelp Dung Beetle
Keystone Species – essential to the balance of an ecosystem, change in their population can cause a dramatic change in the community.
Dung Beetle
Otters and Kelp 5

6. Ecological Succession
Ecological Succession - change in an ecosystem
Primary Succession – no soil (volcanic eruption or bare rock)
first to appear are “pioneer species” Ex: Lichens
Secondary Succession – Soil Exist (wild fires, clear cutting, plowed for farming)
Succession in a Marine Ecosystem – happens when a large whale dies and sinks to the bottom
Climax Community – fairly stable, mature, dominant community established after succession.