Question

Define fundamental niche and realized niche. How do these concepts help us to understand the effects of competitors?

Short answer

Fundamental niches are the potential conditions a species can inhabit, while realized niches are the actual conditions it inhabits due to competition, which helps us understand competitive impacts on species interactions.

Step-by-step solution

Define Fundamental Niche

The fundamental niche of a species refers to the full range of environmental conditions and resources that a species can theoretically use, without considering other species' influence. It is determined by the species' physiological tolerance limits and specific resource needs.

Define Realized Niche

The realized niche is the actual range of environmental conditions and resources that a species uses in nature. It is usually narrower than the fundamental niche due to interactions with other species, such as competition, predation, and symbiosis, which restrict a species' ability to fully occupy its fundamental niche.

Understanding Effects of Competitors

Competitors affect the realized niche of a species by limiting the resources available to it or by occupying part of the environmental conditions that are part of its fundamental niche. This means that in the presence of competitors, a species typically utilizes a reduced set of conditions and resources, resulting in a smaller, realized niche. This concept helps ecologists understand how species distribution and interactions can change in an ecosystem.

Key concepts

Fundamental Niche

The fundamental niche of a species represents the full spectrum of environmental conditions and resources it can potentially use. Imagine it as the ideal living situation for the species where no other organisms interfere. This niche considers factors like:

• Temperature
• Humidity
• Food availability
• Any other resource the species might need

These factors are dictated purely by the species' physiological and genetic characteristics. For example, a plant has a fundamental niche that includes all climates it can survive and grow in, assuming there are no competing plants. Understanding a species' fundamental niche helps us grasp its potential role and distribution in an ecosystem if it were completely isolated.

Realized Niche

While the fundamental niche is all about potential, the realized niche refers to what actually happens in nature. This concept highlights the real-world scenarios where species interactions come into play. Due to interactions with other organisms like:

• Competition
• Predation
• Mutualism or symbiosis

The realized niche is generally smaller than the fundamental niche. For instance, a bird might not occupy all the forests in its fundamental niche because of a predator that inhabits some of these areas. Therefore, the realized niche reflects the actual conditions the species lives in, taking into account these ecological interactions.

Species Interactions

Species interactions play a pivotal role in defining the realized niches. These interactions can be various and have different effects on the species involved:

• Competition: Occurs when species vie for the same resources, affecting their ability to thrive fully.
• Predation: When one species preys on another, it can limit the prey’s realized niche.
• Symbiosis: Includes mutualism, commensalism, and parasitism, each altering the niche in unique ways.

Interaction dynamics shape who lives where and how resources are distributed among species in a community. They provide insight into why two species might partition environments differently or why one might displace another over time.

Ecological Competition

Ecological competition is a major force that limits the expansion of fundamental niches into realized niches. This competition can be:

• Intraspecific: Occurs within the same species; individuals compete for resources like food, mates, and habitat.
• Interspecific: Occurs between different species; competing species might limit each other's niche by occupying overlapping environments.

Competition results in niche differentiation or resource partitioning, where species adjust to use different parts of the resource spectrum to minimize competition. This adjustment is crucial in maintaining biodiversity and stability within ecosystems, as it allows multiple species to coexist by reducing direct competition.