Ecological Niche and Habitat: Meaning, Difference, Narrow and Broad Niche
Ecological niche of an organism is the physical space occupied by it, its functional role in the community i.e. tropic position, its position in environment and the conditions of existence.
Difference between Niche and Habitat
A niche describes how an organism makes its living and responds to the distribution of resources and competitors. The ecological niche involves both the place where an organism lives as well as the roles that an organism does in its habitat. For example, various habitats of house sparrow include woodlands, grasslands, and deserts; houses, factories, warehouses, zoos etc. However, when we talk about its niche, it would include – eating insects, grains, seeds etc.; making nests in houses, trees and shrubs etc. Thus, niche is a broader concept than habitat and its focus is on functional role played by the species rather than only the place it needs to live. For any organism, the niche includes both the physical habitat and how it has adapted to life in that habitat.
In summary, Habitat is “address” while Niche is “profession”.
Organisms that occupy the same or similar ecological niches in different geographical regions are known as Ecological Equivalents. For examples, owls and cats, both feed on mice; but owls are found in deserts or forests while cats are around human habitations. In this context, owls and cats are ecological equivalents in terms of their feeding role. Similarly, Kangaroos of Australia perform the same functions (herbivores) as antelopes or Bison of North America. Both live in similar habitats of different regions but have similar profession of herbivores.
Can two species share the same niche?
Each species has one Niche; no two species can share the same niche for long because then the competition for resources will drive the inferior species out. This is called character displacement or niche shift or niche displacement. Further, please note that competition for food, light and space is most severe between two closely related species occupying same niche.
Narrow Niche and Broad Niche
When an organism is adapted various kinds of environmental conditions for its survival, it has a generalized or broad niche. Such organisms are called generalists. On the other hand, if the organism needs specific set of conditions for its survival, it has a specialized niche or narrow niche. Such organisms are called specialists.
There are many species of plants and animals which can survive only a narrow range of climatic or environmental conditions. For example, Giant Panda has a very specialized niche because 99% of its food is bamboo plants. The destruction of bamboo in China has led the Giant Panda to reach stage of near extinction. Thus, narrow niche is one of the reasons behind the extinction of species.
- Examples of Narrow Niche: Giraffes, Lemurs, Ganges River Dolphin etc.
- Example of Broad Niche: Humans, Rodents, House Sparrows etc.