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ECOLOGY
The term ‘Ecology’ was coined by Reiter in 1865.
The knowledge of the sum of the relations of organisms to the surrounding outer world, to organic and inorganic conditions of existence (Ernst Haeckel, 1886).
Krebs (1985) defined ecology in simple modern comprehensie way as “ecology is the scientific study of the interactions that determine the distribution and abundance of organisms”.
Scope of Ecology. Ecology plays an important role in ariculture (crop rotation, weed contrd etc), management of gross lands, forestry, biological surveys, pest control, fishery biology, conservation of soil wildlife, forest, water supplies etc. The international problem of environmental pollution also needs ecological assistance.
Level of Organisation Basic division of Biology
Organic molecules Biochemistry
Subcellular organelles Cell biology
Cells
Tissues Histology
Orgas Organ system Anatomy, Physiology
Organism
Populations Communities Ecology
Ecosystems
Important Term of Ecology
i. Population is a group of individual organisms of the same species in a given area.
ii. Community is a group of populations of different species in a given area.
iii. Diversity is a combination of the number of species and the number of individuals of species in a community.
iv. Ecosystem is the whole biotic community in a given area plus its abiotic environment.
The biotic components of any ecosystem are linked as food chains. Food chains are interlinked to form complex food webs. Food webs are the basic units of ecosystem ecology.
v. Species is generally defined as “a uniform interbreeding population spread over time and space”.
vi. Vegetation The collective and continuous growth of plants in space is called vegetation.
vii. Adaptation Any feature of the organism of its parts which is of definite significance in allowing that organism to exist undr the conditions of its labitat is thus called adaptation.
viii. Ecads An ecad of a plant species is a population of individuals which although belong to the same genetic stock, but differ markedly in vegetative characters such as size, shape, number of leaves, stems etc.
ix. Ecotype is a population of individuals of a species, which are genetically different.
x. Biological Clocks Plant species possess physiological mechanisms that indicate particular seasons of the year, and thus plant species are known as biological clocks.
xi. Ecotone There is generally a zone of transition, presenting a situation of special ecological interest between two different types of communities, which is known as an ecotone.
xii. Biological Spectrum The percentage disribution of species among the various life forms of a flora is called the bidogical spetrum of that place.
xiii. Ecological Succession is a natural process by which different groups or communities colonize the same area over a period of time in a definite sequence.
xiv. Climax In the natural process of succession, one community continues to follow another, until a stage comes when a type of community cannot be displaced under the prevailing environmental conditions. This final, terminal community that can maintain itself more or less indefinitely in equilibrium with the prevailing environment, is known as the climax community and the stage is said to be the climax.
xv. Ecological Niche of an organism includes the physical space occupied by it, its functional role in the community.
xvi. Ecological Equivalents Organisms that occupy the same or similar ecological niches in different geographical regions are known as ecological equivalents.
xvii. Autecology ecology of individuals, where we study the relotion of individual species to its environment.
xviii. Synecology ecology of community is known as synecology.
xix. Bione Several types of communities maintained under more or less similar climatic conditions is known as a bione.
Abiotic Components The abiotic components of the ecosystem comprise both climatic and edaphic factors.
Climatic Factors include temperature humidity, rain and snowfall.
Edaphic Factors comprise the soil and substratum. The ability of organisms to utilize, tolerate or combat the various abiotic factors are different and it may limit their disribution, behaviour and relationship with other organisms. Some of the moist important abiotic factors are given below
