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Ecology, or ecological science, is the scientific study of the distribution and abundance of and how the distribution and abundance are affected by interactions between the organisms and their . The environment of an organism includes both physical properties, which can be described as the sum of local factors such as (sunlight), , and , as well as the other organisms that share its . The term oekologie was coined in 1866 by the German biologist , although it seems that Henry David Thoreau had already invented it in 1852 [1] ; 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.
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Ecology is usually considered a branch of , the general science that studies living . Organisms can be studied at many different levels, from and (in and ), to (in ), to individuals (in , , and other similar disciplines), and finally at the level of , communities, and , to the as a whole; these latter strata are the primary subjects of ecological inquiries. 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 , ecology draws heavily on many other branches of science, especially and , , , , and . Thus, ecology is considered by some to be a , one that over-arches older disciplines such as biology which in this view become sub-disciplines contributing to ecological knowledge.
Agriculture, fisheries, forestry, medicine and urban development are among human activities that would fall within Krebs' (1972: 4) explanation of his 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 and have provided a scientific basis for expressing the aims of and evaluating its goals and policies. Additionally, a of nature is stressed in both ecology and environmentalism.
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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:
- (or ecophysiology) and examine adaptations of the individual to its environment.
- (or autecology) studies the dynamics of populations of a single species.
- (or synecology) focuses on the interactions between species within an ecological community.
- studies the flows of energy and matter through the biotic and abiotic components of .
- 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, insect ecology, and so on. Another frequent method of subdivision is by biome studied, 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 plant community ecologist, or a polar ecologist interested in animal genetics.
Ecology can also be studied at several levels: level (individuals of the same species), level (or community of species), level, and level.
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The first principle of ecology is that each living organism has an ongoing and continual relationship with every other element that makes up its environment. An can be defined as any situation where there is between organisms and their environment.
In an ecosystem, the connections between species are generally related to and their role in the . There are several categories of organisms: Producers -- usually plants which are capable of but could be other organisms such as bacteria around ocean vents that are capable of ; Consumers or animals, which can be primary consumers (), or secondary or tertiary consumers ().
which can affect dynamic change in a or in a given ecology or environment are usually divided into two groups: abiotic and biotic.
Ecosystems are not isolated from each other, but are interrelated. For example, may circulate between ecosystems by the means of a or . Water itself, as a liquid medium, even defines ecosystems. Some species, such as or freshwater move between marine systems and fresh-water systems. These relationships between the ecosystems lead to the concept of a ; a homogeneous ecological formation that exists over a large region as or . The comprises all of the Earth's biomes -- the entirety of places where life is possible -- from the highest mountains to the depths of the oceans.
The biosphere may also be divided into , which are very well defined today and primarily follow the continental borders. The ecozones are themselves divided into , though there is not agreement on their limits.
Generally, an occurs when the of a species or a population evolves in a way unfavourable to that species survival.
For more on fundamental principles and subfields of ecology, see the submenu, below:
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[1] , by Michel Serres, in Ctheory, May 11, 2006