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Organisms and Populations

Organisms and Environment

  • Ecology deals with interactions among different organisms and their environment.

  • Organisms get adapted to their environment for their survival and reproduction.

  • The rotation of the earth about its axis brings about changes in the environment, leading to different seasons. This leads to the formation of various biomes such as desert, grassland, etc.

  • Life not only exists in favourable habitats, but also in harsh and extreme conditions.

​Habitat and niche

  • It is a physical space occupied by an organism.
  • It is a set of environmental conditions according to which an organism adapts to survive.
  • There are several abiotic factors like temperature, rainfall, types of soil and sunlight which determine the presence of a particular species in an area.
  • A habitat consists of several niches.
  • Habitat is not species-specific, which means any type of species can occupy the same habitat and thrive together.
  • Examples of habitats are desert, ocean, mountain, forest, grassland, etc.  
  • It is an ideology of how an organism lives or survives in the provided environmental conditions. 
  • Ecological niche involves both physical space occupied by an organism and functional role played by the particular species in its community.
  • It also describes how a species contributes to the energy flow of a system.
  • Niche is species-specific, which means only one type of species can occupy a niche at a particular time.
There are three aspects of an ecological niche-
  • Spatial or habitat niche- It is the physical space within a habitat occupied by a species. No two species can occupy the same habitat.
  • Tropic niche- It explains the trophic position or functional status of a species in a food chain. It explains how different species share the same habitat but occupy different trophic niches.
  • Hypervolume or multidimensional niche- It explains the relationship between a species and the environmental gradient. A large number of abiotic and biotic factors affects the functioning of the population. 

For every species, there is a fundamental niche and a realized niche.

  • Fundamental niche- It is the niche in which an organism survives and reproduces in the absence of competitors or any kind of limiting factors.
  • Realized niche-  It is the actual space which an organism inhabits in the presence of interspecific competition. It is more realistic in nature. 

The environment of an organism can be divided into:

  • Abiotic factors

  • Biotic factors

Abiotic Factors

  • Some of the major abiotic factors that interact with the organisms are:

    • Temperature − It is the most relevant abiotic factor since all organisms require an optimum temperature for their metabolism and other body functions. Depending upon their ability to tolerate temperatur…

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