Fundamental Ecological Concepts and Interactions

Core Ecological Definitions

Population: A group of individuals of the same species that lives in a determined area.

Biotope: The place or physical environment occupied by a community.

Ecosystem: The combination of the community (biocenosis) and the biotope where it lives.

Ecology: The science that studies the interactions between living beings and with the physical environment around them.

Habitat: The type of place where an organism has the necessary conditions to live. It has two types of factors:

• Biotic factors: Emerge as a consequence of the presence of other living beings, such as the struggle for food or space, or mutual help.
• Abiotic factors: Are not directly dependent on living beings, although their activity can modify them (e.g., light, moisture).

Life in the Aerial Environment

Temperature

The temperature of the atmosphere is highly variable. In one place, it varies depending on the day or night and the seasons. Changes in altitude and latitude are accompanied by changes in temperature. Organisms are classified according to the sources of their body heat:

• Ectotherms: Their body temperature depends on external sources of heat, such as solar radiation.
• Endotherms: They can control their body temperature by producing heat internally.

Humidity

Humidity is the amount of water vapor present in a given volume of air.

Abiotic Factors of the Soil

Soil Texture

Soil texture is determined by the size of the mineral particles that compose it. There are:

• Sandy soils
• Clay soils
• Mixed soils

Water and Air

Soil pores are filled with air or water. The water needs are not the same for all organisms living in the soil. For example, water-loving plants like the bulrush require a lot of water, while xerophytic plants like the cactus do not. Air fills the soil pores that are not occupied by water and are connected with the atmosphere.

Soil Salinity and pH

Salty soils have a particular flora and fauna. Neutral soils are usually preferred by most plants.

Life in the Aquatic Environment

Salinity

Freshwater has less than 5 g/L of dissolved salts, while the saltwater of the seas has between 33 and 37 g/L.

Light

Water absorbs more light radiation than air. According to the illumination, three zones are distinguished:

• Euphotic Zone: Receives enough light for photosynthesis.
• Oligophotic Zone: Receives minimal light.
• Aphotic Zone: Receives no light.

Temperature

In the aquatic environment, temperature variations are much less pronounced than in the air. Even so, they play an important role.

Biotic Factors: Interspecific Relationships

Predation

Predation is an interspecific relationship in which a predator eats other living organisms (prey). There are various types:

• True predators: Kill and consume their prey.
• Grazers/Browsers: Attack a large number of prey but may not kill them outright.
• Parasites: A special type where the organism lives on or in a host, causing it harm.

Mutualism and Commensalism

These are interspecific relationships in which none of the species involved are harmed.

• Mutualism: Brings benefits to both organisms.
• Commensalism and Inquilinism: One species benefits while the other is unaffected.