Ecology and the Interdependence of Life on Earth

Definition of Ecology

• Ecology: Study of relations of organisms to one another and their physical environment.
• Focuses on interactions and dependencies among living and non-living components.

Interdependence

• Species depend on both living organisms and non-living components.
• Example: Humans need plants for oxygen; plants need carbon dioxide from humans.

Ecological Models

• Due to complexity, ecologists use models to describe ecological systems.
• Ecosphere: The largest ecological model, representing all of Earth's components.
• Biosphere: Earth's thin layer where life exists, from atmosphere to ocean depths.

Ecosystems

• Definition: All organisms and their non-living environment in a specific place.
• Example: Pond ecosystem includes fish, turtles, aquatic plants, etc., and non-living factors like pH and oxygen levels.

Levels of Organization

1. Biosphere: Entire Earth where life exists.
2. Ecosystem: All living and non-living components in a specific area.
3. Community: All interacting organisms in an area (excludes non-living factors).
4. Population: All organisms of one species in an area.
5. Organism: An individual entity of a species.

Habitats and Niches

• Habitat: The place where an organism lives (includes biotic and abiotic factors).
• Niche: An organism's role or job in its environment.
• Habitat Example: Foggy coastal area.
• Niche Example: Converting sun energy into sugar (photosynthesis by redwood trees).

Biotic and Abiotic Factors

• Biotic: Living parts of the habitat (e.g., plants, animals).
• Abiotic: Non-living parts of the habitat (e.g., rocks, sunlight, temperature).

Generalists vs. Specialists

• Generalists: Organisms that eat various foods, adaptable to multiple habitats (e.g., pigs).
• Specialists: Organisms with specific dietary needs, higher extinction risk (e.g., pandas).