Organisms and Populations

Habitat and niche

  1. Ecosystem is segment of nature consisting of both biological community and its physical environment which exchanges and interacts chemical/materials as well as energy.
  2. A large regional unit restricted by a specific climate, having a particular major vegetation and its associated fauna, is called as a Biome.
  3. The major biomes are tropical rain forest, savannah, deserts, temperate grasslands, deciduous forest, Alpine (Taiga/Tandra).
  4. Grinnel in 1917 has termed niche (or) Ecological niche as a specific part of habitat occupied by individual of same species that is circumscribed by its range of tolerance, range of movement, types of food and its availability, shelter, type of predator and time of activity.
  5. Major abiotic factors that affect the behaviour, structure of the organisms are light, temperature, water, soil and wind.
  6. Megatherms – plants growing in high temperature. Eg: Tropical rainforest.
  7. Mesotherms – plants growing in alternate high/low temperature. Eg: deciduous vegetation.
  8. Microtherms – plants growing in low temperature. Eg: coniferous forest.
  9. Hekistotherms – plants growing in very low temperature. Eg: alpine vegetation.
  10. Organisms existing in a wide range of salinities are called Euryhaline (Eg. Salmon) but others are restricted to a narrow salinity range called as stenohaline (Eg. Shark).

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