Chapter 9: ORGANISMS AND ENVIRONMENT - I

The two main components, organisms and their environment, are very much complex, dynamic, interdependent, reactive and interrelated.

The term ecology was coined by combining two Greek words as Oikos (house or dwelling place) and logos (study).

Ecology is a branch of biology which deals with the interactions among living organisms (biotic) and between the organisms and their physical (abiotic) environment.

It is also called environmental science.

An ecosystem is a functional unit of nature, where organisms interact with each other and their surroundings. 

9.1 Habitat and niche

There are many external forces, substances or conditions, which can affect the living organism in one or the other way.

They are considered as factors. The sum of all such factors forms the environment (can be better referred as environmental complex).

The place where a particular organism lives is called Habitat.

Ecological niche

Though the term niche was first used by Grinnel (1971) to explain microhabitats, it should not be confused with habitats.

The ecological niche is an inclusive term which involves not merely the place occupied by the organism but also its functional role in the community.

There are three aspects of ecological niche as

1. Spatial or habitat niche - The physical space occupied by the organism.

2. Trophic niche - The trophic position of the organism and its functional role.

3. Multidimensional or hyper volume niche - Position of the organism in the environmental gradients

Thus the ecological niche helps in understanding

1. How organism transforms energy, behaves, responds to and modifies its physical and biotic environment

2. How it is constrained by other species.

 The concept of ecological niche is thus significant in ecology to understand the differences between the species at same physical place or at different places or the same species at more than one location.