Biodiversity - Ecosystems and Niches

This section defines key terms related to biodiversity: ecosystem and niche. Understanding these concepts is fundamental to comprehending how organisms interact with each other and their environment.

Ecosystem

Definition

An ecosystem is a community of living organisms (plants, animals, and microorganisms) interacting with each other and with their physical environment (abiotic factors) such as soil, water, air, and sunlight.

Components of an Ecosystem

Ecosystems are composed of two main components:

• Biotic Factors: The living organisms within the ecosystem. This includes producers (plants), consumers (animals), and decomposers (bacteria and fungi).
• Abiotic Factors: The non-living components of the ecosystem. Examples include temperature, rainfall, sunlight, soil type, and water availability.

Types of Ecosystems

Ecosystems can vary greatly in size and type. Some common examples include:

• Forests
• Grasslands
• Deserts
• Aquatic ecosystems (freshwater and marine)
• Coral reefs

Ecosystem Processes

Several key processes occur within ecosystems:

• Energy flow: The transfer of energy from the sun to producers and then to consumers.
• Nutrient cycling: The movement of essential elements (like carbon, nitrogen, and phosphorus) through the biotic and abiotic components of the ecosystem.
• Food chains and food webs: The feeding relationships between organisms within the ecosystem.

Niche

Definition

A niche describes the role and position of a species within an ecosystem. It encompasses all the biotic and abiotic factors that affect a species' survival and reproduction.

Components of a Niche

A niche includes:

• Habitat: The physical environment where a species lives.
• Food source: What the species eats.
• Interactions with other species: Competition, predation, symbiosis, etc.
• Environmental conditions: The range of temperature, humidity, light, etc., that the species can tolerate.

Types of Niches

There are different types of niches:

• Fundamental niche: The full range of environmental conditions and resources a species *could* potentially use.
• Realized niche: The portion of the fundamental niche that a species *actually* uses due to competition and other limiting factors.

Niche Overlap and Competition

When two or more species have overlapping niches, they may compete for resources. This can lead to one species outcompeting the other, or to the development of niche partitioning (where species evolve to use different resources or habitats).

Table summarizing Ecosystem and Niche

Feature	Ecosystem	Niche
Definition	Community of interacting organisms and their physical environment.	Role and position of a species within an ecosystem.
Components	Biotic (organisms) and Abiotic (environment) factors.	Habitat, food source, interactions, environmental conditions.
Scale	Can vary greatly in size (e.g., a pond, a forest).	Specific to a species.
Focus	Interactions between all organisms and their environment.	How a species fits into the ecosystem.