28.6
Ecological Niches
An ecological niche describes the role of an organism within its environment. The niche includes all the biotic, or living, and abiotic, or nonliving, resources and conditions that the organism uses.
For example, the niche of a hare includes abiotic factors such as the climate where it can survive and the terrain that provides shelter and protection from predators.
Biotic factors include other hares with which it interacts, the plants it eats, and the predators that feed on it.
A fundamental niche is the full range of resources and environmental conditions that an organism could use. A realized niche is the narrower range of resources that a species actually uses.
Competition with other species often limits the size of the realized niche.
If competition from other species is reduced or removed, the species may begin to use more of the resources that it could potentially use. As a result, its realized niche can expand toward its fundamental niche.
While members of the same species often share some resources in the same area, two different species cannot occupy the same niche indefinitely. If they do, one would outcompete the other.
So how can similar species live in the same place without one driving the other out?
One way species avoid competition is by gradually dividing resources. This process is called resource partitioning. This division of limited resources allows species to coexist instead of competing directly.
Ecologically similar species may evolve to use different resources. They may also share the same resources but use them at different times or in different places.
A classic example of resource partitioning comes from Robert MacArthur's research on warbler species in the forests of New England.
MacArthur showed that although the warblers appear to use the same resources, live in the same trees, and consume the same insects, they actually occupy different areas of the trees.
This spatial partitioning of resources allows five species of warblers to coexist within the same trees.
All organisms have a position within an ecosystem. The complete set of living and nonliving factors—including food resources, climate, and terrain—that define the position of a given organism are collectively referred to as the organism’s ecological niche.
Multiple species cannot occupy the exact same niche within their habitat. If the niches of two or more species overlap to a large extent, the competitive exclusion principle dictates that one species will outcompete the other, forcing it to adapt or die out. However, flexibility in the resources an organism uses can allow similar species to coexist if they modify their realized niches to avoid competition.
Further, it appears that there is often a correlation between niche size and geographical range. Species with niches that are broader are generally found across a larger geographic area. Such larger distributions might give these species more flexibility in the realized niche, allowing them to adapt to environmental changes or the presence of competitors more easily than a species with a narrower niche and smaller geographic range.
Understanding how organisms function together in their ecosystem through their ecological niches can help guide conservation efforts for vulnerable areas and endangered species, as well as limiting the threat posed by invasive species.
An ecological niche describes the role of an organism within its environment. The niche includes all the biotic, or living, and abiotic, or nonliving, resources and conditions that the organism uses.
For example, the niche of a hare includes abiotic factors such as the climate where it can survive and the terrain that provides shelter and protection from predators.
Biotic factors include other hares with which it interacts, the plants it eats, and the predators that feed on it.
A fundamental niche is the full range of resources and environmental conditions that an organism could use. A realized niche is the narrower range of resources that a species actually uses.
Competition with other species often limits the size of the realized niche.
If competition from other species is reduced or removed, the species may begin to use more of the resources that it could potentially use. As a result, its realized niche can expand toward its fundamental niche.
While members of the same species often share some resources in the same area, two different species cannot occupy the same niche indefinitely. If they do, one would outcompete the other.
So how can similar species live in the same place without one driving the other out?
One way species avoid competition is by gradually dividing resources. This process is called resource partitioning. This division of limited resources allows species to coexist instead of competing directly.
Ecologically similar species may evolve to use different resources. They may also share the same resources but use them at different times or in different places.
A classic example of resource partitioning comes from Robert MacArthur's research on warbler species in the forests of New England.
MacArthur showed that although the warblers appear to use the same resources, live in the same trees, and consume the same insects, they actually occupy different areas of the trees.
This spatial partitioning of resources allows five species of warblers to coexist within the same trees.
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28.6 : Ecological Niches
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28.2 : Distribution and Dispersion
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28.7 : Symbiosis
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28.8 : Competition
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28.9 : Predator-Prey Interactions
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28.10 : Keystone Species
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28.11 : Ecological Disturbance
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28.12 : Ecological Succession
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