All ecological factors work not everyone in itself, and the whole complex. Action of one of them depends on the level of the others. The organism reacts to influence of ecological factors the adaptive reactions called adaptation, and allowing it to live and exist in new conditions.
1. The ecological factors making impact on the world around, a set. They unite in three groups: abiotic, biotic and anthropogenic. Carry the factors of inanimate nature directly or indirectly influencing organisms to the first: light, temperature, humidity, chemical composition of the soil and air, etc. In other words, it properties of the environment which do not depend on activity of biological objects. Biotic factors represent forms of influence of living beings at each other, for example, impact of microorganisms on plants, plants on animals and vice versa. Anthropogenic are different types of human activity which lead to change of conditions of dwelling of organisms or affect their existence.
2. The nature of influence of these factors can be established. Any organism lives in conditions of a certain environment and can exist only in the established limits of its convertibility. The most favorable level of an ecological factor is called optimum. At its excessive influence the vital activity falls. The area of tolerance, or range of action, an ecological factor is limited to points of a maximum and a minimum. Beyond their limits the existence of an organism is impossible. The limits are characteristic of each being, for example, the room fly lives at air temperature from 7 to 50 degrees, and an ascarid – only at a temperature of a human body.
3. It is necessary to consider that any living organism is influenced by a complex of factors, but only one is limiting (limiting). For example, distribution of some animal species and plants from the South on the North is limited to a lack of heat, and as the factor in the south limiting for the same plants the shortage of moisture can serve.
4. In size of range of action of a factor you can judge endurance of organisms. Biological objects which exist in various environmental conditions are called evribiontny. It is possible to carry the brown bear living in conditions of a warm and frigid climate, in damp and dry areas, using both vegetable, and animal food to them. Stenobiontny organisms adapt to life in the narrow range of change of environmental conditions. For example, the trout lives only in clear water of the cold mountain rivers.