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Life scientists generally define a biological niche as the status of an organism in its environment, both biotic and abiotic. The niche that an organism occupies is comparable with its habitat, but incorporates ecological variables such as position in space and time, and interaction with other organisms. Thus the habitat of a bird may be a particular type of woodland, whereas its niche describes the role which it plays within that habitat; what and where it eats, where it nests, etc. Implicit in the term niche is the conclusion that without the bird the woodland is different. Differences between niches can be subtle, but, by definition, only one species can occupy a given niche. The occupying species is, however, likely to experience competition from other species living in similar niches this is known as the competitive exclusion principle. The idea of the niche is thus rooted in speciation and natural selection, and is therefore dynamic. Where similar habitats are geographically isolated, each may contain similar niches occupied by very different species these are termed ecological equivalents. RB
See also ecosystem; fitness. |
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