Ecology – types and levels

The term ecology is derived from Greek words oikos, meaning the “family household”, and logy. meaning “to study”. This term was formed by the German zoologist Ernst Haeckel in 1866. He called it oecologic. Ecology is defined as the study of the relationship of organisms to their environment. This relationship, includes interactions with the physical world and w ith members of other species and the same species. The organisms are directly affected by the,., environment. Similarly activities of organisms try to change the environment.


The physical and biological conditions under which an organism lives is called environment. The environment may organic or inorganic. Organic environment includes all the living organisms. Inorganic environment includes light. temperature. soil fire, wind etc.

The scope and development of ecology

Ecology is the study of distribution and abundance of organism. It includes the study of factors vi Inch control the number and location of the organisms. There are different levels of ecology. Interactions of the organism and environment take place in each level. These levels are:

  1. Organismal ecology

It is also called autecology or physiological ecology. It is concerned with the behavioural, physiological and morphological ways of living of an organism. Each organism has certain limits of tolerance: These limits determine the habitat of the organism.

  1. Population

The group of inter-breeding individuals belonging to same species and living in a common geographic area is called population. Population is the next level of  ecology .The various kinds of organisms that inhabit an ecosystem make up populations: The populations of plants and animals do not function independently in an ecosystem. Some populations compete with other populations for resources such as food, water, or space. In some cases. one population is the food resources for another. Two populations may mutually benefit each other. A population can be described in terms of member, growth rate, and age distribution.

Ecological Hierarchy

  1. Community

All populations within an ecosystem are known as a community. The populations in a community are interconnected to one another. The individuals of these populations interact among themselves and with individuals of other species to form a community. The interactions are predation, competition, parasitism, commensalisms, mutualism and grazing.

  1. Biomes

The major regional ecological community of plants and animals are called biomes. Each biome consists of different combinations of plants and animals. These plants and animals fully developed to form climax community. Each biome is characerized by a uniform life form of vegetation such as grass or coniferous trees. There are six major terrestrial bionics: Forest. Gras land, Wood land, Shrub land, Semi desert shrub and Desert.

  1. Ecosystem

A biological community bigether with the associated abiotic environment is called ecosystem. The ecosystem is a major unit of ecology. Organisms interact with their environment within an ecosystem. The eco part of the word related to the environment and the system.part means a collection of related parts functioning as a unit. The study of ecosystem includes energy Bow and cycling of the chemicals between biotic and abiotic components. The ecosystem consists of two basic interacting components:

(a) Biotic component: Biotic components consist of animals, plants. fungi, micro-organisms etc. and

(b)Abiotic components: Abiotic components are atmosphere. climate. soil, and water.

Types of ecology

  1. Autecology

The study of relationship of a single population to its environment is called autecology. For example. one person is studying the effect of water pollution on 50 to 100 plants of soybean on their growth and yield. As he is studying the single or one population of soybean plant,so this is autecology.

  1. Synecology

The study of relationship of different communities or group of population to their environment is called synecology or community ecology. Growth responses of individua1 plant to environment are a complex factor. One factor increases the affect of other factor. These factors interact With one another. Complexity of environment depends on the combination of various factors. Following factors are studied in synecology:



(i)      The various aspects of community like the origin. structure and composition of the community are studied in synecology.

(ii)     The history of community.

(iii)The dynamics of community because community. is not a fixed entity. But different changes occur at different time.

(iv) Three levels of integration are studied in the community. These are: individual, population and community.


A thin layer of earth in which all living organism exist is called biosphere. Organisms within the biosphere are adapted to the environment. These organisms also interact to modify and control chemical and physical conditions of the tiosphere. An organism lives in a habitat..

An organism responds to a variety of environmental factors. It can inhabit a location when all the environmental factors arc within the range of its tolerance. Biosphere is characterized by two terms:

  1. . Habitat

The place where an organism lives is called its habitat. Habitat may be aquatic or terrestrial. Aquatic habitat may be marine or fresh water. Some organisms are parasites or symbionts. They live on other organism.

2. Ecological Niche

The basic role or profession of an organism in a community is called ecological niche. Niche is a distributional unit. The physical structure and physiological limitations keep species in this distributional unit. The study of :tick includes: What an organism does in a community. What it does fir living community. What are its relationship with its food and enemies? The niche’ is related to a profession or job of an organism. Thus the niche is particularly concerned with the:

(i)          Feeding habits

(ii)         The role of a particular species within an ecosystem

(iii)        All aspects of its interaction with the living and non-living environment.

(iv)       Ecological niche within a habitat also specifies Low the organism gets its supply of energy and materials. For examples, predators-prey relationship of organ isms and competition.

v) Its behaviors and interactions in environment

(vi) Niche also includes all the physical environment factors necessary for survival, such as range of temperature, amount of humidity. the pH of the water and soil.

Ecology as an Experimental Science

The humans always remain interested in other organisms and their environments. The prehistoric people were hunters. .1They had to learn where animals and plants were found. Many natural historians from Aristotle to Darwin observed and described organisms in their natural habitat. Thus the old natural history formed the basis of ecological science.

Ecology has a long history of being descriptive science. But most modem ecologists are skilled scientists. They perform different experiments. For example: There is question: the squirrels eat acorns plants. How does it

affect the distribution’ and abundance of oak trees? Experiments are required to answer this question. These experiments require a large area of land from which squirrels can he removed. Another. •large area is required for controls It also requires a long period of time in which to observe results.

Thus there is a great difficulty for conducting experiments in ecology. Rut still many creative ecologists are testing hypotheses in the laboratory. They are also experimentally manipulating populations and communities in the field.

Many ecologists also use mathematical models to answer ecological questions. Important variables and their relationships are described through mathematical equations. Computer is also used in the study of ecology. This is very useful approach. It allows the ecologists to conduct experiments in laboratory.


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