What are biotic and abiotic factors?

We explain what biotic and abiotic factors are, how they are related and various examples. Also, what are trophic chains.


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Biotic and abiotic factors and their relationships constitute the environment.

What are biotic and abiotic factors?

Biotic and abiotic factors are two of the central elements that ecology studies , that is, the scientific discipline that is dedicated to ecosystems to understand the way in which relationships between life and the inert elements that surround it are built.

Thus, biotic factors are those living beings that inhabit an ecosystem , feeding on it, reproducing and serving as a sustenance for other species. On the contrary, abiotic factors are those that have their origin in inert matter , that is, they are the set of chemical materials and physical forces that constitute the ecosystem and that exert certain determined effects on living beings.

All ecosystems are composed of these two types of factors , between which more or less complex relationships are woven, which constitute the environment . Human beings are not exempt from this type of relationship, although they differ from other animals in that they have the psychic and technological tools to modify the environment, instead of irremediably adapting to it, as other species do in their habitats . respective.

See also: Components of the environment

Biotic factors and examples

Biotic factors are characterized by their desire for survival.

The term “biotic factors” refers, essentially, to the flora, fauna and funga of an ecosystem, that is, to the total of the species of plants , fungi and animals . Microorganisms (microflora and microfauna) can also be included, depending on the level of detail with which the ecosystem is studied.

These biotic factors are characterized by their desire for survival, that is, they are organisms that fight to preserve internal order and continue to exist, and by their reproductive capacity, that is, their innate tendency to produce more new individuals of the species. In this way, the different species of living beings that share a habitat are in continuous competition for the resources available for food and for the search for protection from natural elements (such as rain, cold or heat).

For this reason, many species make a continuous effort to control the necessary resources, be it food, territory, water or fertile females for reproduction , which they compete with other species (interspecific competition) as well as with the other individuals of the species. its own species (intraspecific competition).

At the same time, many species build bonds of cooperation and mutual aid , known as cooperative relationships (inter- and intraspecific): mutualism , in which both individuals or species benefit; commensalism , in which they share resources without particularly harming or benefiting each other and symbiosis , in which they cooperate so closely, that they depend on each other for survival.

Examples of biotic factors are:

  • Animalsreptiles , fish, birds, mammals , worms, sponges, echinoderms, among many others.
  • Both multicellularand unicellular microorganisms , such as bacteria , archaea and protozoa .
  • The planktonof the seas: zooplankton (animal) and phytoplankton (vegetable).
  • Fungi and yeasts, both free-living and parasitic .
  • Plant species: trees, shrubs, plants, vines, grasses, algae, among many others.

More in: Biotic factors

food chains

Heterotrophic organisms can be herbivorous and feed on plants.

The competitive relationships between living beings are complex and lead to the exchange of matter and energy between different species. That is, the matter that makes up the body of a living being is assimilated by another when it feeds on it , as predators do when ingesting and digesting their prey. In addition, when the latter die, the matter of their bodies is assimilated by the decomposing species, thus returning to the circuit.

Depending on the place that a species occupies within this cycle of transmission of matter, also called the food chain or trophic chain , we can distinguish between three sets of living beings:

  • Produceror autotrophic organisms . Those that are capable of generating their own food from inorganic elements, such as water, sunlight or soil elements. In this group are plant species and a few other autotrophic organisms, which give rise to organic matter, transforming inorganic matter to their advantage.
  • Consumeror heterotrophic Those who cannot generate their food from inorganic elements, but must consume the organic matter of other living beings. Those that consume the organic matter of the producing organisms are known as herbivores or primary consumers; while those that consume the organic matter of primary consumers (and other types of consumers) are known as carnivores or secondary consumers. For example: A deer is a primary consumer, since it feeds on leaves and stems; while a panther feeds on deer and is therefore a secondary consumer. Between one and the other there may also be other intermediate consumers.
  • decomposing organismsor detritophagous . Those that feed on the organic matter of producers and consumers, but once they have died and their body begins the decomposition process. Detritus eaters are in charge of recycling organic matter back into the circuit of life, since they not only feed on the body of deceased beings, but also break it down into simpler substances that producers or autotrophs use for their benefit (that is, organic fertilizer ).

More in: Food chain

Abiotic factors and examples

Abiotic factors do not have a life of their own but are used by living beings.

The term “abiotic factors” covers a very diverse set of non-living components of an ecosystem , such as water , air , sunlight, gases in the atmosphere or mineral components of the soil. These elements do not have a life of their own, but are essential for the existence of living beings , since they are used by producers to generate organic matter: plants, for example, use carbon dioxide , sunlight, and water to produce organic molecules . (sugars).

In addition, abiotic factors affect living beings in various ways, forcing them to adapt to their environment . The change in temperature in the cold seasons , for example, forces trees to lose their leaves to save water in times of low sunlight, and many animals to accumulate resources to hibernate during the worst weather stage.

Abiotic factors can be classified according to their nature into two sets:

  • Chemical factors. Those that have to do with the constitution of matter, such as water, air gases (oxygen, hydrogen, nitrogen, among others) and mineral elements of the soil (calcium, iron, phosphates, among others).
  • physical factors. Those who have to do with natural forces, movement and energy, such as sunlight, ambient temperature, meteorological phenomena ( rain , hail, snow, among others) or landforms .

Finally, are examples of abiotic factors:

  • Solar radiation, which provides light and heat to the earth’s surface.
  • The different stages of waterin its hydrological cycle : ice, liquid water, water vapor in the atmosphere or raindrops in precipitation.
  • The ambient temperatureand atmospheric pressure , which determine the climate that changes cyclically throughout the year.
  • Soil minerals, different types of rocks and relief accidents.
  • The tidescaused by the attraction of the Moon.

More in: Abiotic factors

Relationship between biotic and abiotic factors

Abiotic factors condition the forms of adaptation of biotic factors.

Biotic and abiotic factors are continuously and closely related. On the one hand, the abiotic elements serve as a starting point for biotics to feed themselves , as in the case of autotrophic nutrition, or for respiration , a process in which living beings ingest useful gases for their metabolism , such as oxygen.

On the other hand, the natural elements shape the ways of survival of living beings , fostering an adaptive response on their part, that is, forcing them to protect their survival in different ways or to take advantage of good times. Rain, for example, is essential for plant life and to cool the environment, keeping the climate stable.

So, in a very dry season, living beings must compete for the available water, which may imply migration to more humid geographies and, therefore, the fight for territory with other species. Something different happens in the deserts , whose continuously dry environment favors the adaptation of the creatures, which develop over the generations bodies and metabolisms capable of minimizing the consumption of water or retaining reserves of this substance inside.


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