Overview
This lecture introduces ecosystems, focusing on the distinction between living (biotic) and non-living (abiotic) factors, and explains how to identify each within an environment.
Ecosystems and Their Components
- An ecosystem consists of living organisms and their physical (non-living) environment.
- Ecosystems vary in size, from small (a log) to large (Yellowstone National Park).
- All ecosystems include both biotic (living) and abiotic (non-living) factors.
Biotic (Living) Factors
- Biotic factors are organisms that possess all seven characteristics of life.
- Characteristics of living things: have cells, consume energy, regulate systems (homeostasis), grow, sense and respond to stimuli, organized structure, reproduce.
- Examples of biotic factors: trees, grass, birds, squirrels, mushrooms, moss, earthworms, bacteria.
Abiotic (Non-living) Factors
- Abiotic factors lack one or more characteristics of living things.
- Rocks cannot reproduce or have cells, so they are abiotic.
- Clouds, while moving and changing, do not have cells or grow independently, so they are abiotic.
- Other abiotic examples: wind, water, fire, oxygen, temperature, sunlight.
Interaction in Ecosystems
- The interaction between biotic and abiotic factors forms complex, interconnected ecosystems.
- Living organisms rely on non-living components to survive.
Key Terms & Definitions
- Ecosystem — a community of living organisms and their physical environment interacting together.
- Biotic Factor — a living component of an ecosystem, such as plants or animals.
- Abiotic Factor — a non-living component of an ecosystem, like sunlight or water.
- Homeostasis — an organism’s ability to regulate its internal environment.
- Phototrophism — growth of plants toward sunlight.
Action Items / Next Steps
- Practice identifying biotic and abiotic factors in your local environment.