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Bioscience Topics



Ecology, or ecological science, is the branch of biology that studies the relationship of plants and animals to their physical and biological environment. The physical environment includes light and heat or solar radiation, moisture, wind, oxygen, carbon dioxide, nutrients in soil, water and atmosphere. The biological environment includes organisms of the same kind as well as other types of plants and animals.

Ecology can be considered a subfield of environmental science, for which it often is confused. Although both are multidisciplinary sciences that focus on the interactions of populations of organisms, environmental science also addresses interactions of purely physical parameters that do not involve biological systems. Ecology also is confused with environmentalism, which focuses on human-caused damage to the natural environment. Likewise, ecologic or ecological are used as synonyms for “environmentally friendly.”

Although ecology is considered one of the newer sciences, having only become prominent in the second half of the 20th century, studies of animal populations and their environments can be traced back to the Greek philosopher Aristotle and his student Theophrastus. Theophrastus described interrelationships among animals and between animals and their environment as early as the fourth century B.C.E. The field began to blossom with the 1850 publication of Charles Darwin’s The Origin of Species and the work of his contemporary and competitor Alfred Russel Wallace. Wallace recognized the interdependence of animal and plant species and grouped them into communities of living beings, or biocoenosis. In 1875, Austrian geologist Eduard Suess proposed the term biosphere to encompass the variety of conditions that together promote life on Earth.

Since the 19th century, environmentalists and other conservationists have used ecology and other sciences to support their advocacy positions. Environmentalist views often are controversial for political or economic reasons. As a result, some scientific work in ecology directly influences policy and political debate; these in turn often direct ecological research. An example of an influential conservationist advocacy organization is the National Audubon Society, whose public policy office is in Washington, D.C., and deals with Congress, the executive branch of the federal government and the media to try to promote environmental conservation.

The primary principle of ecology is that each living organism has an ongoing and continual relationship with every other element that makes up its environment. An ecosystem can be defined as any situation where there is interaction between organisms and their environment. Within the ecosystem, species are connected by food chains or food webs. Energy from the sun, captured by primary producers (plants) via photosynthesis, flows upward through the chain to primary consumers (plant-eating animals, or herbivores) and then to secondary and tertiary consumers (meat-eating animals, or carnivores), before ultimately being lost to the system as waste heat. In the process, matter is incorporated into the decomposers (such as mushrooms and bacteria), which degrade nutrients and return them to the ecosystem.

The concept of an ecosystem can apply to units of variable size, such as a pond, a field or a piece of deadwood. A unit of smaller size is called a microecosystem. For example, an ecosystem can be a stone and all the life under it. A mesoecosystem could be a forest, and a macroecosystem a whole ecoregion.

An ecological crisis can occur when the environment of a species or a population evolves in a way unfavorable to that species’ survival. The crisis may begin with a change in the climate (such as increased temperature or decreased rainfall), an extraordinary event (such as an oil spill), increased activity of predators feeding on prey (such as overfishing) or explosive growth in the population of the species that can’t be supported by the ecosystem. Over the last few centuries, the actions of humans seriously has affected many ecosystems by reducing the amount of the Earth’s forests (deforestation), by increasing the amount of land devoted to agriculture as well as to buildings and roads and by polluting ecosystems.

Subdisciplines of Ecology

Physiological Ecology (or Ecophysiology) and Behavioral Ecology

These examine adaptations of the individual to its environment.

Population Ecology (or Autecology)

This studies the dynamics of populations of a single species or a related group of species (such as animal, plant or insect ecology).

Community Ecology (or Synecology)

This focuses on the interactions between species within an ecological community.

Ecosystem Ecology

This studies the flows of energy and matter through the components of ecosystems.

Landscape Ecology

This examines processes and relationship across multiple ecosystems or very large geographic areas (for example, Arctic or polar ecology, desert ecology, tropical ecology and marine ecology).

Human Ecology

The type of career one could expect as an ecologist is as wide and varied as the habitats and animals you study. Basically, any situation where research is needed on the interaction between species and the environment requires an ecologist. Ecologists study oceans, deserts, forests, cities, grasslands, rivers and every other corner of the world. More and more, ecologists are teaming with physical scientists, social scientists, policy-makers and computer programmers to understand better how organisms interact with each other and with the environment in which they live. Ecologists can be educators, technicians, field scientists, administrators, consultants and writers.