Ecology
Some Definitions An ecosystem – all the living things in an area plus the physical or abiotic factors. A habitat – the place or environment in which specific organisms live. A species - a group of similar organisms that normally interbreed in nature to produce fertile offspring.
Ecological Niche
Ecological Niche REMEMBER The habitat is an organism’s address. The ecological niche is its profession. A limiting factor is any variable environmental factor that limits the activity of an organism or population.
Explain More the niche is the “role” the species plays in the community of interacting species. This includes: Where it lives What it eats How it responds to stress What limits its population growth. It is the whole of the organism’s use of the biotic and abiotic resources in its environment.
Ecological Niche Gause’s Principle Simply put the niche is a description of the opportunities provided by the habitat and the adaptations of the organism to make the most of those opportunities. Gause’s Principle No two species with identical ecological niches can coexist for long in the same place.
Fundamental Niche This refers to the resources a population could theoretically use in an ideal situation.
Realised Niche This refers to the resources a population can actually use (remember it is affected by all the interactions with other organisms).
Example 2 species of barnacle grow on the rocky shore. Balanus balanoides and Chthamalus stellatus C. stellatus, which are smaller, live at the top of the rocks, while the B. balanoides, the larger, live lower down. The bigger barnacles can’t stand the period of dryness when the tide goes out, the small barnacles can.
Example If you remove all the B. balanoides from lower down, the smaller ones, C. stellatus, move quickly in and are very happy there. It’s just that they normally can’t stand the competition from the bigger barnacles. The fundamental niche for the small barnacle is the whole of the rock, but its realised niche is the upper layers of the rock.
Barnacles