The niche

The Ecological Niche

Definition

  • The ecological niche refers to the functional role of a species within a community, including its activities and relationships.

Fundamental Niche

  • Defined as the total range of environmental conditions under which a species can survive.

Resource Utilization and Environmental Factors

Key Factors

  • Environmental aspects contributing to niches include:

    • Temperature

    • Humidity

    • Salinity

  • These factors create varying optimal conditions for different species.

Temperature Preferences

  • Different plant species have varying optimum temperatures for photosynthesis based on their origin:

    • Temperate lowland: 80-250 m

    • Mountain valley: 530-900 m

    • High mountain communities: 2500-2600 m

Dimensions of Niches

One-Dimensional Niche

  • Species inhabit niches based on a single resource dimension, such as temperature.

Two-Dimensional Niche

  • Species distribution across two environmental factors, displaying limits for individuals versus populations:

    • Zones where populations thrive, such as optimal range, compared to limits of tolerance.

Coexistence of Species

Resource Utilization Curves

  • Illustrates relationships of species along a resource spectrum, demonstrating niche overlap:

    • Narrow niches with limited overlap lead to less interspecific competition.

    • Broader niches result in intense competition.

Practical Example

  • Feeding positions of bat species in coniferous forests are another instance showing niche utilization and concentration in certain zones.

Realized Niche

  • Realized niches are influenced by competition, which may limit species distribution and population dynamics:

    • Example: Barnacle species Cthamalus and Balanus illustrating zonation in distribution due to competition.

Competitive Release

  • Refers to niche expansion that occurs when interspecific competition is reduced, allowing species to utilize resources previously beyond reach.

Specialized and Changeable Niches

  • Niche characteristics can be both specialized and adaptable to environmental shifts, seen in mobile sand dune ecosystems.

Limits to Niches

Ecological Constraints

  • Altitudinal and latitudinal limits apply to many niches, affecting species distribution and adaptation.

  • Ecotones are transitional areas between different community types, indicating shifts in niches.

Phenotypic Variation

  • Physical expression of a characteristic of an organism, determined by both genetic constitutions and environment

  • Example: Achillea lanulosa exhibits growth variations due to environmental constraints, showcasing the relationship between phenotype and niche adaptation.

  • The morphology of birch trees differs between coastal and inland environments, affecting their growth forms due to environmental stressors.

Biomes

  • Defined as biological subdivisions reflecting specific physiological and ecological characteristics of plant life, broader than individual niches.

  • Plant communities are classified based on temperature and precipitation:

    • Ranges from Tropical Rainforest to Tundra based on environmental factors.

Climate Change Implications

  • Current discussions include how climate change might affect existing niches and biomes.

Summary of Key Concepts

  • Fundamental Niche: Total environmental range suitable for survival.

  • Realized Niche: Actual niche exposed to competition.

  • Resource Utilization Curves: Graphical representation of resource use and competition.

  • Competitive Release: Expansion of niche due to decreased competition.

  • Environmental factors like altitude and latitude define limits to niches.

  • Different environments can produce varying phenotypes from single genotypes.

References

  • Acknowledgements to various ecological studies and texts that informed this material.