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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.
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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.
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 • 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