Community Ecology

A. What is a community?

1. assemblage of populations in a common area

-Alpine Forest in Snowy Range, Medicine Bow Mountains, Wyoming

-mighty fortress tree

2. What are the properties of a community?

insects in Texas prairies

-species richness

-relative abundance

B. Interspecific Interactions

1. What types of interactions occur?





2. Competition

-Competitive Exclusion Principle

G.F. Gause

-experiments with Paramecium species:

P. aurelia

P. caudatum

-if two species compete for the small resources one will become extinct

-What is the niche?

resource partitioning in lizards

3. Predation

-What are the types of predation?

Examples of predator adaptations

-acute vision in falcons

-heat sensing in rattlesnakes

Examples of prey adaptations:

-cryptic coloration

-aposematic coloring

-Batesian mimicry

3. Commensalism and Mutualism

-cattle egrets

C. Trophic Structure of a Community

1. What does "trophic" mean?

2. What are food chains?

What is the pattern of trophic levels in the food chain?

3. What is a food web?

4. What limits the length of a food chain?

-the impact of thermodynamics on energy conversion

D. Disturbances and Community Structure

1. Are communities stable or do they change?

Is there a "balance of nature"?

2. What is the impact of routine disturbances?



3. What is the impact of major disturbances?

-role of ecological succession

a. primary succession

-newly formed volcanic islands (Surtsey)

-Mt St. Helens

-retreating glaciers

-steps of primary succession:

succession pattern of vegetation

changes in soil nitrogen

b. secondary succession

-Yellowstone fires Yellowstone in 2006