ECOLOGY

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).

Taylor (1936) defined ecology as “the science of all the relations of all organisms to all their environments”.  “The study of the structure and function of ecosystems” by Odum 1969.

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