ECOLOGY
Ecology ‘Oikos’ meaning home or place to live in and ‘logos’ meaning study. Literally it is the study of the home of nature.
Ecology is defined “as a scientific study of the relationship of the living organisms with each other and with their environment.”
It deals with the ways in which organisms are moulded by their environment, how they make use of environmental resources including energy flow and mineral cycling.
1.1. HISTORY OF ECOLOGY
The roots of ecology lie in Natural History, which is as old as human civilization itself. Since early history, man has indulged in ecology in a practical sort of way, knowingly and unknowingly. In primitive societies every individual was required to have an intimate knowledge of his environment for their survival, i.e., about the forces of nature and of plants and animals around him/her.
Our ancient Indian texts have references to ecological principles. The classical texts of the Vedic period such as the Vedas, the Samhitas, the Brahmanas and the Aranyakas-Upanishads contain many references to ecological concepts. The Indian treatise on medicine, the Charaka-Samhita and the surgical text Sushruta-Samhita, show that people during this period had a good understanding of plant and animal ecology.
These texts contain classification of animals on the basis of habit and habitat, land in terms of nature of soil, climate and vegetation; and description of plants typical to various localities. Charaka- Samhita contains information that air, land, water and seasons were indispensable for life and that polluted air and water were injurious to health.
1.2. ENVIRONMENT AND ITS COMPONENT
Everything that surrounds or affects an organism during its life time is collectively known as its environment.
The environment is defined as ‘the sum total of living, non-living components; influences and events, surrounding an organism.
All organisms (from virus to man) are obligatorily dependent on the other organism and environment for food, energy, water, oxygen, shelter and for other needs.
The relationship and interaction between organism and environment are highly complex. It comprises both living (biotic) and non-living (abiotic) components.
The environment is not static. Both biotic and abiotic factors are in a flux and keeps changing continuously.
Components of Environment | |
Abiotic | Biotic |
Energy Radiation | Green plants Non-green plants Decomposers Parasites Symbionts Animals |
Temperature & heat flow Water Atmospheric gases and wind Fire Gravity Topography Soil Geologic substratum | Man |
For instance: Let’s take the environment of a fish in the pond.
External environment of fish
♤ Its environment consists of abiotic components such as light, temperature, including the water in which nutrients, oxygen, other gases and organic matter are dissolved.
♤ The biotic environment consists of microscopic organisms called plankton which it assume as well as aquatic plants, animals and decomposers.
Internal environment of fish
♤ It is enclosed by the outer body surface.
♤ The internal environment is relatively stable as compared to the external environment.
♤ However, it is not absolutely constant. Injury, illness or excessive stress upsets the internal environment.
♤ For example, if a marine fish is transferred to a fresh water environment, it will not be able to survive.
1.3 LEVELS OF ORGANISATIONS IN ECOLOGY
The main levels of organisation of ecology are six and are as follows.
