Ecological Niches

Definition of Niche:
- Role of a species in its ecosystem.
- Considers environmental conditions, interactions with other species, activity patterns, and resource availability.
Niche Components:
- Physical & environmental tolerances
- Intra- and interspecific interactions
- Temporal activity patterns
- Resource acquisition (e.g., temperature, competition)
Types of Niches:
- Fundamental Niche: All the resources and habitat a species could theoretically utilize.
- Realized Niche: Actual resources and habitat a species uses due to competition.
Competitive Exclusion Principle:
- No two species can occupy the same niche for extended periods.
- One species will adapt and thrive while the other may face extinction or migrate.
Niche Partitioning:
- Similar species coexisting by utilizing different resources within the same habitat (spatial, morphological, or temporal).
Natural Selection and Niches:
- Species can evolve to have broad (generalists) or narrow (specialists) niches.
- Specialists are less adaptable and more likely to face extinction under changing conditions.
Adaptations:
- Species adapt structurally, physiologically, and behaviorally to fit their niche.
Factors Affecting Distribution:
- Biotic: Competition, predation, symbiosis.
- Abiotic: Climate, soil pH, temperature, water availability.
Keystone Species:
- Species that have a disproportionate effect on their ecosystems; their removal can lead to significant changes in community structure.
- Example: Pisaster ochraceus study showing how its removal drastically reduced species diversity.
Autotrophs vs. Heterotrophs:
- Autotrophs (Producers): Create organic compounds from inorganic sources (e.g., plants, some bacteria).
- Heterotrophs (Consumers): Obtain energy and nutrients by consuming other organisms (e.g., animals, fungi).