Lesson 6 - Niches and Interrelationships Flashcards
Ecological Niche
Ecological niche - the habitat, resources, interactions, and conditions that enable an organism to survive.
The niche that an organism occupies is determined by two main factors:
The opportunities provided by the habitat
The adaptive features of the organism which enable it to take advantage of the opportunities.
Fundamental vs Realised Niche
Fundamental niche -
Where a species would live in an ideal world if we only consider the abiotic factors and what conditions the organism is adapted for. This assumes the absence of competition. It is the full extent of the ecological niche that an organism can occupy.
Realised niche -
When competition and predation (biotic factors) also affect the distribution of an organism and where it can live. This assumes that competitors are present to restrict a species to a smaller niche. This often produces patterns of species in an area (zonation).
Interspecific Relationships
Interspecific relationships are between an organism and another species, and they always benefit one party.
Interspecific relationships are very important because they affect essential processes such as food chains and nutrient cycles. Over time, convolution can occur in response to the way species interact.
Example of Fundamental vs Realised Niche - brown and blue barnacles
Fundamental niche -
Brown barnacles can occupy the entire intertidal zone. They have adaptations that allow them to survive long periods of aerial exposure in the high tide zone.
Realised niche -
Blue barnacles are more competitive than brown barnacles in the MTZ and LTZ, so brown barnacles can only survive in the HTZ (even though it is able to survive in all zones per abiotic factors).
Blue barnacle is the best competitor, however it is not as tolerant as the brown barnacle because it can only survive in the LTZ and the MTZ, whereas the brown barnacle can survive in all three zones. Blue barnacle has created a zonation pattern by pushing the brown barnacle strictly to the HTZ.
Brown barnacle is best adapted to the rocky shore because list abiotic factor and adaptations.
Gause’s Principle of Competitive Exclusion
Two species with overlapping ecological niches cannot coexist. One species will always outcompete the other—the species that loses will have to find a new niche or die out, i.e. species with similar needs for the same limiting resource cannot coexist in the same place.
