Ecosystem Interactions: Competition, Predation, and Symbiosis

Organismal Relationships

• Organisms interact in various ways within an ecosystem.

Interactions Between Organisms

• Interactions often arise from:
  • Competition for food and resources (e.g., during famine).
  • Mating (e.g., fights over females).
  • Defense against attackers.
  • Asserting dominance within a group.

Types of Interactions

• Competition: Individuals or groups vie for resources.
  • Example: Two cheetahs competing for a piece of meat; the most fit cheetah wins.
• Predation: One organism consumes another for energy.
  • Example: A barracuda eats a fish.
• Symbiosis: Organisms cooperate to survive.
  • Example: A clownfish and sea anemone work together.

Detailed Look at Competition

• Territoriality:
  • Common among male animals of the same species.
  • Establishes dominance and domain in an area.
  • Involves:
    • Fighting.
    • Sounds (e.g., elk bugles).
    • Scent marking (e.g., animals urinating to mark territory).
• Aggression: Attack behavior between two animals.
  • Example: Two seagulls fighting over a limited resource.

Predation Explained

• Predator-Prey:
  • One organism (predator) consumes another (prey) for energy.
  • Example: Barracuda eating a fish.
• Herbivory:
  • An herbivore eats a plant.
  • Considered predation even though the plant cannot escape.
• Parasitism:
  • A parasite feeds off another organism (host) but doesn't immediately kill it.
  • Example: Tomato hornworm eating a tomato plant.

Symbiotic Relationships (Preview)

• Clownfish and Sea Anemone:
  • Clownfish lives in sea anemone.
  • Both benefit from the relationship; they cooperate and survive together.
• Shark and Remoras:
  • Remoras follow sharks and benefit, while the shark is unaffected.
• Tapeworm:
  • Tapeworm lives off a host by consuming its nutrients.