NH

Lecture Notes on The Niche

The Niche

Historical Context

  • Joseph Grinnell (1917)

    • Concept introduced: Niche as the physical habitat requirements of a species

    • Key variables: Abiotic conditions (temperature, moisture, geography, etc)

    • Significance: The Grinnellian niche is still used in species distribution modeling

  • Charles Elton (1927)

    • Concept expanded: Niche as “what it does,” encompassing

      • Species' place in the community

      • Relations to food and enemies

      • Impact on energy flow

    • Distinction made:

    • Grinnell’s niche: A species’ home

    • Elton’s niche: A species’ profession

  • George E. Hutchinson (1957)

    • Advanced definition: Niche as an n-dimensional hypervolume that describes how a species fits into its ecosystem

    • Defined two niche types:

      • Fundamental niche: The ideal conditions and resources for species survival

      • Realized niche: The actual conditions under which species exist, accounting for interactions like competition and predation

Defining the Niche

Grinnell's Niche

  • Definition: Physical habitat requirements of a species

  • Parameters considered:

    • Abiotic factors such as temperature, moisture, and geography

  • Application: Utilized in various environmental modeling processes

Elton's Niche

  • Key statement: Niche reflects a species' role within a community

  • Aspects evaluated:

    • Trophic role and position in the food chain

    • Movement of nutrients and energy (how resources turn into biomass)

    • Community interactions (what a species eats and what eats it)

Hutchinson's Concept

  • Definition of niche as an n-dimensional hypervolume

  • Dimensions defined:

    • Biotic dimensions (interactions with other species)

    • Abiotic dimensions (physical habitat characteristics)

  • Importance: Provides a comprehensive understanding of ecological interactions and energy flow

Fundamental and Realized Niche

Fundamental Niche

  • Definition: The n-dimensional hypervolume of biotic and abiotic parameters where an organism can survive and reproduce

  • Characteristics: Involves ideal conditions without interference from other species

Realized Niche

  • Definition: The actual conditions where a species exists considering interactions such as competition and predation

  • Implication: Organisms generally do not occupy the entirety of their fundamental niche due to interspecies dynamics

Competitive Exclusion Principle

  • Definition: Proposed by Georgyi Gause in the 1930s, indicating that two species competing for the same limiting resource cannot coexist indefinitely in a stable environment

    • Empirical Evidence:

    • Example: Growth of two species of Paramecium when grown separately and in combination illustrates this principle; one species outcompetes and leads to extinction of the other

  • Applications: Understanding this principle is vital in ecology for predicting species interactions and community structure

Implications of Niche Dynamics

Health and Disease

  • Connection to microbiota balance:

    • Impact of antibiotics, diet, tobacco, and lifestyle on gut microbiome and its associated niches

  • Dysbiosis: Alters intestinal niche leading to proliferation of opportunistic bacteria and associated health risks