Transcript Community Ecology (Ch. 20)

Community Ecology
Species Interactions
Major types of interactions:
1. Predation
2. Competition
Symbiotic Relationships:
3. Parasitism
4. Mutualism
5. Commensalism
1. Predation
Predators vs. Prey
-Who eats whom and how. Why?
-Regulates population size.
-Variations lead to natural selection.
-Natural Selection leads to ‘Survival’…carry on the
species!
Predator Adaptations
-sensory
-physical (teeth, web’s, striped coloration)
Prey Adaptations
Animals:
1. being able to flee….
2. camouflage
3. deceptive markings
4. chemical & physical defenses
5. bright colors
6. mimicry (Batesian & Mullerian)
Plants:
1. Physical Defenses
2. Secondary Compounds
Which snake is poisonous?
The nonvenomous king snake (right), for
example, closely mimics the color pattern of
the venomous coral snake.
Polyohemus Moth: deceptive markings!
Physical Defense:
Thorns and spines.
Chemical Defenses & Bright Colors
Secondary Compounds…Poison
Ivy!
2. Competition
Interspecific Competition: one species is eliminated because of
competition for the same resources.
Competition can lead to:
1. Character Displacement: Natural selection at work;
Darwin’s Finch case study…beak shape. A benefit to reduce
competition…increases survival; reduces niche overlap.
2. Resource Partitioning: Increased competition
between species because they require the same
resources. When coexistance occurs, each species only
uses part of the available resources…reduction in
competition…increases survival!
3. Parasitism:
Parasite vs. Host
Ectoparasites vs. Endoparasites
4. Mutualism:
Both species benefit.
5. Commensalism:
One species benefits, the other is not affected.
Ch. 20-2…Properties of Communities
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Species Richness- the number of species the community has.
Species Evenness- the relative abundance of each species.
Patterns of Species Richness:
1. Latitude
2. Habitat Size
3. Interactions and Species
4. Community Stability
Successional Changes in Communities
Ecological Succession- growth of a species in a given area.
1. Primary (very slow process)
-pioneer species
2. Secondary (quick return of organisms)
Climax Community