Ecology Interactions: Population, Community, Symbiosis, and Cooperation, Slides of Biology

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Interactions:

Populations and

Communities

Population Interactions

• A population of organisms has properties that are different from those individuals that make up the population
• Cooperation and competition between individuals contribute to these properties

Community Interactions

• Classified by whether they help, harm or have no effect on the species involved
• Species interactions strongly influence the structure of communities
• Community : A group of populations of different species in an area

Examples of Community Interactions

• Interspecific competition (-/-)
• Predation (+/-)
• Herbivory (+/-)
• Symbiosis
  • Parasitism (+/-)
  • Mutualism (+/+)
  • Commensalism (+/0)

Interspecific Competition (-/-)

• Individuals of different species compete for a resource that limits their growth and survival

Predation (+/-)

• An interaction in which one organism captures and feeds on another organism
• Predator and prey
• What are some advantages of predation? (Think!)

Herbivory (+/-)

• Interaction in which an organism eats parts of a plant or alga

Plant Defenses Against Herbivory

• Chemical defenses – produce chemicals that are toxic or taste bad
• Mechanical defenses – prickles, thorns, spines or trichomes
• Thigmonasty – responses to touch, leaves curl up or close
• Leaf shedding or warning coloration

Symbiosis – Commensalism (+/0)

• A symbiotic relationship in which one organism benefits and the other organism is neither helped nor harmed

Symbiosis – Mutualism (+/+)

• A symbiotic relationship in which both organisms benefit

Community Interactions

Ecosystem Stability

Food Chain Stability

Food Web Stability