Environmental Factors, Ecosystems, and Populations

Environmental Factors and Their Influence

Environmental factors are characteristics of the environment that affect living things. These can be categorized as:

• Abiotic factors: Physical and chemical conditions.
• Biotic factors: Organisms that share the same natural environment.

Limiting Factors and Adaptation

Limiting factors are environmental conditions that restrict the growth and abundance of a population within an ecosystem. Adaptation is the evolutionary process where organisms become better suited to survive in a specific environment.

Population Dynamics

A population is a group of organisms of the same species that live in the same territory and can reproduce together. Within populations, we can observe different structures:

• Colonies: Resulting from asexual reproduction, individuals are genetically identical.
• Families: Characterized by relationships between parents and their offspring.

Communities and Ecosystems

A community is a group of populations that live in the same area and interact with each other. An ecosystem encompasses all the living organisms and their interactions within a specific environment. Key components include:

• Biotope: The physical environment where living things reside.
• Biocenosis: The communities that inhabit the biotope.
• Ecotone: A transitional area between two ecosystems where they meet and integrate.

Matter and Energy Flow

Sources of matter include chemical elements and inorganic molecules from the abiotic environment, which are transformed into organic molecules by living things. Chemical elements are constantly recycled. The primary source of energy is the Sun, which is converted into chemical energy used by living organisms. Unlike matter, energy is not reusable.

Biogeochemical cycles describe the movements of chemical elements in nature, involving both organic and inorganic matter.

Trophic Levels and Ecological Interactions

A food chain is a linear representation of how matter and energy are transferred from one organism to another. This transfer occurs in a single direction.

Biomass refers to the total amount of matter in an organism, a population, a trophic level, or an ecosystem. Productivity is the relationship between net production and biomass at any trophic level. Ecological pyramids visually represent the different trophic levels in an ecosystem.

Population Growth and Sustainability

Carrying capacity is the maximum number of individuals in a population that a specific environment can support. Species can exhibit different growth strategies:

• R-strategists: Species that utilize environmental resources efficiently and can grow rapidly.
• K-strategists: Species that are well-adapted to their environment, with stable populations and controlled growth.

Survival curves are graphs that illustrate the relationship between the survivors of a population and the average age of the species. Population sizes can change due to:

• Fluctuations: Non-periodical changes, often caused by natural phenomena.
• Cyclical changes: Caused by seasonal variations or interactions between different species.