Ecology: Understanding Ecosystems and Environmental Factors

Key Ecological Concepts

Ecology is the science that studies the relationships between living beings, and also between them and their surrounding environment.

• Population: A group of individuals of the same species living together in a given area.
• Community: A group of populations living together in a specific area.
• Biotope: The physical environment or habitat occupied by a community.
• Ecosystem: The combination of the community and the biotope in which they live, including the ways in which individuals interact with one another and with their surrounding environment to reproduce and form a stable system.

Environmental Factors

The environment is influenced by various factors:

• Biotic factors: Factors that result from the presence and activities of other living beings.
• Abiotic factors: Factors that are not dependent on living beings, although the activity of organisms can modify them.

Optimal Conditions and Tolerance Limits

• Optimal: The environmental conditions where a species grows most rapidly, leaves more offspring, and survives best.
• Limit of tolerance: The range of environmental conditions beyond which the survival of the species is impossible, and the population may disappear.
• Limiting Factors: Factors that hinder the growth of a species. Some factors may be limiting for one species while fostering the growth of another.
• Zones:
  • Lethal: Below -8°C and above +38°C
  • Optimal: +18°C to +28°C
  • Tolerance: +8°C to +38°C

Life in Terrestrial Environments

Temperature: Temperature is related to biological activity. When temperatures are low, some organisms enter a period of lethargy.

• Homeotherms: Organisms whose body temperature does not depend on the environment (e.g., birds and mammals).
• Poikilotherms: Organisms whose body temperature depends on external sources of heat (e.g., reptiles, amphibians, and fish).

Humidity: The amount of water vapor in the atmosphere. Living things contain a high percentage of water that they need to stay alive.

• Terrestrial animals: They lose water through evaporation or waste disposal and may compensate for the loss through eating and drinking.
• Plants: They lose water through aerial parts and absorb water from the soil through their roots.

Life in Aquatic Environments

Salinity: Most aquatic species live only in either fresh or salt water, and only some can tolerate variations in salinity and survive in both environments.

Light: There are three zones based on light penetration:

• Euphotic: Receives sufficient light for plants to perform photosynthesis.
• Oligophotic (or twilight zone): Receives limited light.
• Aphotic (or midnight zone): Receives no light, resulting in total darkness.

The Threat of Climate Change

Climate change: Pollution in all its forms greatly affects biodiversity. However, the greatest threat is the increasing possibility of climate change due to greenhouse gases.