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Community Interactions

• What is a community?

Community Interactions

• Competition

• Predation

• Symbiosis– Mutualism– Commensalism– Parasitism

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Competition

• Competitive Exclusion—4 results:

– G.F. Gause (P. caudatum & P. aurelia)

– Connell (barnacles) – niche partitioning

– Resource partitioning – ex. warblers

– Character displacement -- evolutionary

Predation—Animal Adaptations

• Mimicry

– Batesian mimicry — Harmless species imitates a dangerous species

– Mullerian mimicry — two or more dangerous species look similar

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Predation—Plant Adaptations

• Physical Defenses– Spines

– Sticky hairs

– Tough leaves

• Chemical Defenses– Poisonous

– Irritating

– Bad-tasting

Secondary compounds

Symbiosis

• Mutualism—both organisms benefit

• Commensalism—one organism benefits & the other neither benefits nor is harmed

• Parasitism—one organism benefits & the other is harmed (host)

– 2 types of parasites

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Mutualism

Commensalism

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Parasitism

Ectoparasite Endoparasite

Ecological Succession

• Primary Succession (No soil present)– No soil exists (newly exposed areas)– Occurs after volcanic activity– Begins with pioneer species (lichens)

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Ecological Succession

• Secondary Succession (Soil present)– Occurs after the existing community has been disturbed w/o removing soil

– Occurs after wildfires, plowing land

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