Chapter 44: Community Interactions

Community: All the interacting populations in an ecosystem

Competition
Predation
Symbiosis

The Ecological Niche - A species way of life, each species in an ecosystem occupies its own niche

Fundamental niche - the set of resources a population is theororetically capable of using under ideal circumstances
Realized niche - the set of resources the population actually uses (due to competition and resource partitioning)

Compare the following fish eating birds that live near a lake

Heron- wades in water, spears fish on the shoreline
Kingfisher - perches and nests in trees, hunts by swooping and spearing prey
Loon - a duck-like bird that paddles and dives to catch fish

Each bird lives in the same ecosystem, eats the same food, but occupies a different NICHE

Competitive Exclusion Principle - no two species can occupy the same niche. If two species with the same niches are places together, they will be forced to compete, one will survive.

Resource Partitioning - species with similar requirements coexist but occupy smaller niches than they would if they lived alone.

Other examples of interspecific competition and resource partitioning

5 species of warblers hunt for food in different areas of a tree
2 species of barnacles occupy deeper and shallower areas of a shoreline

Tutorial: Competition in Action (Niches)