fv9 - trophic levels

AP Environmental Science: Unit 1 – The Living World: Ecosystems

Topic: 1.9 Trophic Levels

Overview of Trophic Levels

  • Energy Management in Ecosystems

    • Ecosystems regulate energy usage through trophic levels.

    • Lower trophic levels (e.g., plants) have higher populations than higher levels (e.g., predators).

  • Types of Organisms

    • Autotrophs/Producers

      • Plants capture glucose and convert it into energy.

      • They create their own food and do not rely on other organisms.

    • Heterotrophs/Consumers

      • Organisms that consume food created by autotrophs.

      • Primary Consumers: Eat autotrophs.

      • Secondary Consumers: Eat primary consumers.

      • Tertiary Consumers: Eat secondary consumers.

  • Food Chains vs. Food Webs

    • Food chains are inadequate to represent feeding habits due to multiple types of consumers.

    • Food Web: A complex network of interconnected food chains representing various feeding relationships.

Energy Transfer and Loss

  • Energy Loss in Trophic Levels

    • Less than 10% of energy remains as one moves up each trophic level.

  • Role of Decomposers

    • Decomposers, scavengers, and detritivores are crucial for nutrient cycling.

    • They prevent the buildup of dead organic matter and recycle nutrients back into the ecosystem.

Types of Consumers

  • Scavengers

    • Consume dead animals before decomposition (e.g., raccoons, vultures).

  • Detritivores

    • Break down dead tissues and waste (e.g., dung beetles).

  • Decomposers

    • Convert organic matter into simpler substances (e.g., worms, fungi, bacteria).

Ecological Relationships

  • Types of Interactions

    • Mutualism: Both organisms benefit (e.g., bees and flowers).

    • Commensalism: One organism benefits, the other is unaffected (e.g., barnacles on whales).

    • Parasitism: One organism benefits at the expense of the other (e.g., tapeworms).

    • Predator-Prey Relationship: One organism kills and consumes another, limiting population growth.

  • Defensive Mechanisms in Prey

    • Prey may develop behavioral, morphological, or chemical defenses against predators.

Competition and Resource Sharing

  • Competition for Resources

    • Occurs when organisms share limited resources (e.g., food, water, shelter).

  • Resource Partitioning

    • Species can coexist by dividing resources (e.g., different parts of a plant).

    • Overlapping resource use can lead to population declines.

Key Terms to Review

  • Community Ecology: Study of species interactions within a habitat.

  • Consumers: Organisms that obtain energy by consuming others.

  • Decomposers: Break down dead organic matter, releasing nutrients.

  • Detritivores: Consume detritus, aiding in decomposition.

  • Food Web: Represents multiple feeding relationships in an ecosystem.

  • Law of Thermodynamics: Energy cannot be created or destroyed, only transformed.

  • Mutualism: Both species benefit from the interaction.

  • Natural Selection: Traits become more or less common based on survival and reproduction.

  • Niche: The specific role of an organism in its ecosystem.

  • Predator-Prey Relationship: Dynamic interaction where one organism hunts another.

  • Scavengers: Feed on dead or decaying organic matter.

  • Secondary Consumers: Feed on primary consumers.

  • Tertiary Consumers: Feed on secondary consumers.

  • Trophic Levels: Different levels in a food chain or web where organisms obtain energy.