Ecology

Ecology, or ecological science, is the scientific study of the distribution and abundance of living organisms and how the distribution and abundance are affected by interactions between the organisms and their environment. The environment of an organism includes both physical properties, which can be described as the sum of local abiotic factors such as solar insolation, climate and geology, as well as the other organisms that share its habitat. The term oekologie was coined in 1866 by the German biologist Ernst Haeckel, although it seems that Henry David Thoreau had already invented it in 1852; the word is derived from the Greek οικος (oikos, «household») and λόγος (logos, «study»); therefore «ecology» means the «study of the household [of nature]". The word «ecology» is often used in common parlance as a synonym for the natural environment or environmentalism. Likewise «ecologic» or «ecological» is often taken in the sense of environmentally friendly.

Ecology is usually considered a branch of biology, the general science that studies living organisms. Ecology is a multi-disciplinary science. Because of its focus on the higher levels of the organization of life on earth and on the interrelations between organisms and their environment, ecology draws heavily on many other branches of science, especially geology and geography, meteorology, chemistry, and physics. Agriculture, fisheries, forestry, medicine and urban development are among human activities that would fall within explanation of the definition of ecology: «where organisms are found, how many occur there, and why».

As a scientific discipline, ecology does not dictate what is «right» or «wrong». However, ecological knowledge such as the quantification of biodiversity and population dynamics have provided a scientific basis for expressing the aims of environmentalism and evaluating its goals and policies. Ecology is a broad discipline comprised of many sub-disciplines. A common, broad classification, moving from lowest to highest complexity, where complexity is defined as the number of entities and processes in the system under study, is:

§ Physiological ecology and Behavioral ecology examine adaptations of the individual to its environment.

§ Population ecology studies the dynamics of populations of a single species.

§ Community ecology focuses on the interactions between species within an ecological community.

§ Ecosystem ecology studies the flows of energy and matter through the biotic and abiotic components of ecosystems.

§ Landscape ecology examines processes and relationship across multiple ecosystems or very large geographic areas.

Ecology can also be sub-divided according to the species of interest into fields such as animal ecology, plant ecology, and so on. Another frequent method of subdivision is by biome studies, e.g., Arctic ecology (or polar ecology), tropical ecology, desert ecology, etc.

The primary technique used for investigation is often used to subdivide the discipline into groups such as chemical ecology, genetic ecology, field ecology, statistical ecology, theoretical ecology, and so forth. Note that these different systems are unrelated and often applied at the same time; one could be a theoretical community ecologist, or a polar ecologist interested in animal genetics.