Ecology - Unit 9

Introduction to Ecology

• Definition: Ecology is the study of interactions between living things and their physical environment.
• Levels of Organization:
  • Organism: Individual living being (e.g., an alligator).
  • Population: Group of the same species in an area (e.g., alligators in a swamp).
  • Community: Different species living in one area (e.g., alligators, turtles, birds in the Everglades).
  • Ecosystem: Organisms plus climate, soil, water, rocks, nonliving components.
  • Biome: Collection of ecosystems with similar climates and plant communities.
  • Biosphere: Earth's crust, waters, and atmosphere supporting life.

Biotic vs. Abiotic Factors

• Biotic: Living things affecting the environment.
• Abiotic: Non-living factors affecting populations; can limit types of organisms.

Carrying Capacity

• Maximum number of organisms an area’s resources can support.
• Limited by available abiotic and biotic resources.

Biodiversity

• Variety of living things in an ecosystem.
• Greater biodiversity leads to increased ecosystem stability.

Energy in Ecosystems

• Producers (Autotrophs): Obtain energy from nonliving resources, make own food.
• Consumers (Heterotrophs): Obtain energy by eating other organisms.
  • Herbivores: Eat plants.
  • Carnivores: Eat meat.
  • Omnivores: Eat both plants and meat.
• Decomposers: Break down organic matter, return nutrients.

Food Chains and Food Webs

• Food Chain: Sequence linking species by feeding relationships; energy flows up.
• Trophic Levels: Levels of nourishment in a food chain.
  • Energy transfer between levels is about 10%.
• Food Web: Complex network of feeding relationships within an ecosystem.

Symbiotic Relationships

• Symbiosis: Close association between organisms.
• Mutualism: Both organisms benefit (e.g., oxpecker and rhino).
• Parasitism: Parasite benefits, host harmed (e.g., fleas on dogs).
• Commensalism: One benefits, the other is unaffected (e.g., barnacles on whales).

Cycling of Matter

• Matter cycles in and out of ecosystems.
• Water Cycle: Pathway of water through the ecosystem.
• Carbon Cycle: Movement of carbon between environment and organisms.
• Nitrogen Cycle: Conversion of nitrogen gas to usable forms by bacteria.
• Phosphorus Cycle: Phosphorus moves through food web, no atmospheric portion.

Interactions in an Ecosystem

• Habitat: All biotic and abiotic factors where an organism lives.
• Niche: Role or way an organism lives in its habitat.
• Predation: One organism preys on another.
• Population Density: Number of individuals in a defined space.
• Factors affecting population growth: Immigration, births, emigration, deaths.

Ecological Succession

• Primary Succession: Development of ecosystem in previously uninhabited areas.
• Secondary Succession: Reestablishment of a damaged ecosystem.

Human Impact

• Population Growth: Increases pressure on natural resources.
• Pollution: Undesirable factors added to environment.
• Greenhouse Effect: Gases like CO2 and methane contributing to global warming.
• Importance of preserving biodiversity for ecosystem health and human advancement.