ECOLOGY: ORGANISM AND ITS ENVIRONMENT NEET

13.1 ORGANISM AND ITS ENVIRONMENT 

• Ecology (Oikos = house, logous = study of) is the study of interaction between living organism and their environment (surroundings).
• the term Ecology is coined by Ernst Haeckel (1866), some says Reiter (1865).
• Odum (1971) defined ecology as "study of structure and function of nature".
• Now a days ecology is also called as Environmental biology. 
• Ecology at the organismic level is essentially physiological ecology which tries to understand how different organisms are adapted to their environments in terms of not only survival but also reproduction. 
• Autecology: Interrelationship of species and its environment. 
• Synecology (community ecology): Interrelationship of entire community and its environment.
• Habitat: In ecology, a habitat is the type of natural environment in which a particular species of organism lives. (aquatic, terrestrial, fresh water, marine etc)
• In ecology, a niche is the match of a species to a specific environmental condition. 
• Niche: (the physical position and functional role of a species within the community) describes how an organism or population responds to the distribution of distribution of resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey).
• You may have learnt in earlier classes how the rotation of our planet around the Sun and the tilt of its axis cause annual variations in the intensity and duration of temperature, resulting in distinct seasons. 
• These variations together with annual variation in precipitation (remember precipitation includes both rain and snow) account for the formation of major biomes such as desert, rain forest and tundra.

                             

Biome	Mean temperature in (0C)	Mean precipitation in (cm)
Arctic and alpine tundra	0 to -10	0 to 130
Desert	5 to 23	0 to 50
Conifer forest	0 to 14	50 to 250
Temperate forest	9 to 23	75 to 225
Grass land	0 to 25	30 to 100
Tropical forest	20 to 25	150 to > 400

• Regional and local variations within each biome lead to the formation of a wide variety of habitats. 
• On planet Earth, life exists not just in a few favourable habitats but even in extreme and harsh habitats – scorching Rajasthan desert, perpetually rain-soaked Meghalaya forests, deep ocean trenches, torrential streams, permafrost polar regions, high mountain tops, boiling thermal springs, and stinking compost pits, to name a few. 
• Even our intestine is a unique habitat for hundreds of species of microbes. 
• Major biomes of India : (a) Tropical rain forest; (b) Deciduous forest; (c) Desert; (d) Sea coast
• Temperature, water, light and soil are the most important  key elements that lead to so much variation in the physical and chemical conditions of different habitats. 
• We must remember that the physico-chemical (abiotic) components alone do not characterise the habitat of an organism completely; the habitat includes biotic components also – pathogens, parasites, predators and competitors – of the organism with which they interact constantly. 
• We assume that over a period of time, the organism had through natural selection, evolved adaptations to optimise its survival and reproduction in its habitat. 

Think/Answer

1. why do an organism adopt their environment?

2. Arrange different bioms in order of increasing mean precipitation.

3. Arrange different bioms in order of increasing mean temparature.

4. What are the key elements that lead to so much variation in the physical and chemical conditions of different habitats? 

5. Differentiate between habitat and niche.
6. what are the major bioms of India?