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Ecology and Ecosystems

Trophic Levels

  • Definition: Trophic levels represent the hierarchy of organisms in an ecosystem based on their feeding relationships.

    • Levels:
    • 1. Producers: Create their own food (e.g., plants, algae, some bacteria).
    • 2. Primary Consumers: Herbivores that consume producers (e.g., caterpillars).
    • 3. Secondary Consumers: Carnivores that eat primary consumers (e.g., birds).
    • 4. Tertiary Consumers: Top predators that eat secondary consumers (e.g., birds that eat smaller birds).

  • Decomposers: Break down waste and dead organisms (e.g., earthworms, bacteria, fungi).

Food Chain

  • Definition: A linear representation of how energy flows through an ecosystem.
    • Example: Grass → Caterpillar → Bird.
    • Key Point: One-way flow of energy.

Food Web

  • Definition: A complex network of feeding relationships among various organisms in an ecosystem.
    • Example Organisms: Blue whales, seals, penguins, krill, phytoplankton, and various fish species.

10% Rule

  • Definition: Energy transfer between trophic levels is inefficient; only about 10% of energy at one level is available to the next level.

  • Energy Flow:

    • Producers: 100% energy
    • Primary Consumers: 10% of producers' energy
    • Secondary Consumers: 1% of producers' energy
    • Tertiary Consumers: 0.1% of producers' energy

Producers/Autotrophs

  • Definition: Organisms that can produce their own food through photosynthesis or chemosynthesis.
    • Examples: Plants, algae, some bacteria, phytoplankton.

Consumers/Heterotrophs

  • Definition: Organisms that acquire energy by consuming other organisms.
    • Examples: Animals, fungi, most protozoa, most bacteria.

Detritivores & Decomposers

  • Detritivores: Organisms that feed on dead organic matter (e.g., earthworms).
  • Decomposers: Organisms that break down dead organisms and waste (e.g., bacteria and fungi).

Limiting Factors

  • Definition: Conditions that limit the growth of a population.
    • Categories:
    • Density Dependent: Factors that depend on population size (e.g., competition, predation).
    • Density Independent: Factors that affect populations regardless of size (e.g., natural disasters).

Symbiosis

  • Definition: Close relationships between two species, where at least one benefits.
    • Types:
    • Mutualism: Both species benefit (e.g., pollinators and flowering plants).
    • Parasitism: One organism benefits, and the other is harmed (e.g., ticks on mammals).
    • Commensalism: One organism benefits, and the other is unaffected (e.g., barnacles on whales).

Fitness

  • Definition: An organism's ability to pass its genetic material to its offspring.
    • Higher fitness = More offspring, lower fitness = Fewer offspring.

Niche

  • Definition: The role an organism plays in its ecosystem, including its habitat, resource use, and interactions with other organisms.
    • Example: Different warblers feeding at various heights in a tree.

Carrying Capacity

  • Definition: The maximum number of individuals that an environment can sustainably support, influenced by resources and conditions.

Biodiversity

  • Definition: The variety of living organisms in an ecosystem, crucial for resilience and stability.

Biotic and Abiotic Factors

  • Biotic Factors: Living components of an ecosystem (e.g., plants, animals, bacteria).
  • Abiotic Factors: Non-living components of an ecosystem (e.g., air, water, temperature).

Ecosystem

  • Definition: A community of living organisms and their interactions with the abiotic environment.

Competition

  • Definition: The struggle for limited resources among organisms in the same habitat.

Population Density

  • Definition: The number of individuals per unit area in a habitat.

Adaptation

  • Definition: An inherited trait that enhances an organism's ability to survive and reproduce in its environment.

Water Cycle

  • Description: The continuous movement of water through evaporation, condensation, precipitation, and runoff.

Carbon Cycle

  • Description: The flow of carbon through the atmosphere, organisms, and back, involving processes like photosynthesis and respiration.

Nitrogen Cycle

  • Description: The transfer of nitrogen between the atmosphere, soil, and living organisms, involving processes like nitrogen fixation and denitrification.