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.