You have probably heard of biotic and abiotic environmental factors in the context of ecology. But what exactly is meant by the term «biotic environmental factors»? All aspects of the living environment that affect living beings fall under the biotic factors.
Biotic environmental factors – definition
Biotic environmental factors are environmental factors of living nature that affect an organism. These can either have a promoting or inhibiting effect on the living being or the organism.
The demarcation between abiotic and biotic environmental factors is not always so simple. For example, oxygen produced by plant organisms and required by heterotrophic organisms is still considered an abiotic factor.
Biotic environmental factors – subdivision
To better understand biotic environmental factors, they are often divided into two categories.
Intraspecific biotic environmental factors
the intraspecific biotic environmental factors are influenced by organisms belonging to the same species.
Interspecific biotic environmental factors
the interspecific biotic environmental factors are influenced by organisms that do not belong to the same species.
biotic interaction
All activities of one organism can have a negative, neutral or positive effect on another organism or species. There are a number of basic types of biotic interaction that describe the relationship between two organisms or species.
Biotic environmental factors – animals
When different animal species live together in a region, at least one animal species is affected by the biotic environmental factors.
competitor
Different organisms, whether of the same or different species, compete for resources in nature. The competition is not always related to food, but also to habitat or sexual partners. Individuals of the same species compete for almost all claimed resources because they have the same food or habitat requirements. In this case it is one intraspecific competition.
At the interspecific Competition, competition between species is low. Different animal species have different nutritional needs. Therefore, they also require different resources.
The more similar resource use is between two species, the more difficult it becomes for the two species to inhabit the same habitat.
competitive exclusion principle
That competitive exclusion principle states that the more similar the ecological requirements of the species involved in a community, the lower the probability that they will permanently colonize the same habitat.
The competitive exclusion principle therefore assumes that several identical species cannot occupy the same ecological niche. Otherwise they have to compete for habitat or food.
non-competition principle
Weaker species that cannot compete against other species avoid them. Thus, the reproductive opportunities can remain. If the avoidance of competition is successful, these species can coexist “peacefully”.
Avoiding competition can be successful, for example, through spatial separation or the use of other food sources.
parasitism
Another biotic environmental factor is parasitism. In parasitism, the host organism and the parasite are closely intertwined. The parasite takes advantage of the host while the host is disadvantaged. Parasitism and parasites are also divided into different categories.
Optional parasites
optional Parasites are free-living organisms. This means they rarely infect a host and can live without it.
An example of this are blood-sucking mosquitoes and ticks, but also river mussels. Parasitism in such organisms is often limited to a specific developmental stage. River mussels damage e.g. B. no fish, but their larvae hook into the fish gills and suck blood there.
Obligatory parasites
Obligations Parasites, on the other hand, are parasites that go through all of their developmental stages inside the host. In this case, it means that the parasite cannot live without a host.
The best-known example is probably the tapeworm. However, these obligate parasites can also change hosts. This is the case with pork tapeworms. Here the pig is the intermediate host and the human is the definitive host.
parasitoid parasites
Parasitoids are parasites that always kill their host at the end of their development. The parasitoids generally include insects.
For example, parasitic wasps lay their eggs in moth caterpillars. The larvae hatch inside the caterpillars and feed on the internal tissues of the caterpillar. The caterpillar stays alive until the larvae hatch, after which it dies.
Parasites are often differentiated based on their habitats:
- endoparasites are parasites that live inside their hosts, such as tapeworms and parasitic wasps.
- ectoparasiteslike lice and mosquitoes, live on the surface of their hosts.
With plant parasites, a distinction is made between full parasites and semi-parasites:
- total parasite are completely dependent on their hosts.
- semi-parasite usually only deprive some of their necessary resources. You can carry out all important biotic activities yourself.
symbiosis
A symbiosis occurs when organisms from two different species live together. Both organisms benefit from the symbiosis. This is the big difference from parasitism, where only one organism benefits. The symbiosis is divided into different categories.
Mandatory Mutualism
Obligatory mutualism is a special case of symbiosis. In this type of symbiosis, the two species involved can no longer live without the symbiosis partner.
Such a symbiosis can be found in lichens. Lichens are a community of algae and fungi that are strictly dependent on each other. The habitat is provided by the fungi for the algae. To do this, the algae have to produce organic substances and pass them on to the fungi.
proto-cooperation
Proto-cooperation is a form of symbiosis where living things are not heavily dependent on each other. The living beings are not dependent on this symbiosis because they can also live alone. The proto-cooperation is therefore “voluntary”. An example here is the cooperation between clownfish and anemone.
The clownfish use the anemone to protect themselves from predators. Compared to other fish species, clownfish protect themselves from the anemone’s tentacles with a layer of slime. The flight of the clown fish is advantageous for the anemone because they attract other sea creatures. These are killed by the anemone’s poison and serve to feed the anemone.
Figure 1: Symbiosis between a false clownfish (Amphiprion ocellaris) and splendor anemone (Heteractis magnifica) Source: wikipedia.de
Biotic environmental factors – food relationships
In nature and in an ecosystem there are also so-called nutrient cycleswhich is an important biotic represent an environmental factor. These arise from diverse food relationships in ecosystems. In a nutrient cycle there is three roleswhich occupy the various organisms (see Figure 2).
Plants build up the biomass and are therefore so-called producers. The biomass is then of animals, den consumers, eaten. After the animals die, their biomass is through decomposers remineralized. The minerals obtained from the dead biomass can be used by the producers to build up the biomass.
Figure 2: Cycle of matter through the food chain
Biotic environmental factors – Examples
Both biotic and abiotic environmental factors can be responsible for the formation of ecosystems.
At this point it is important to know that biotic and abiotic factors fundamentally interact with each other. In an ecosystem, therefore, both types of environmental factors usually affect living beings.
Biotic Environment Factor: Forest
The forest as an ecosystem has structures that can arise from the effects of biotic and abiotic environmental factors. These include, for example, the different layers in the foliage of a forest, which are built up like storeys.
Biotic environmental factor: plants
Plants are also an important biotic environmental factor. They work as producers and thus form the basis of life for many animals. They serve as a source of food and also convert inorganic matter into organic matter with the help of solar energy.
Plants are usually considered autotrophic. Which means something like «self-feeding». Animals that feed on plants, on the other hand, are considered heterotroph.
Where which plant species occurs depends in turn on abiotic factors, such as light and water. However, competition with other plant species also plays a role. This is one intraspecific competition.
To make it a little clearer: If plants (e.g. trees) are still growing, they need sufficient light, enough nutrients, etc. Individuals with the best location for this have an advantage. If the trees do not get enough sun during their growth phase, e.g. B. because they are covered by other plants, they eventually die. This is an example of intraspecific competition.
However, when the trees are mature, the intraspecific competitor decreases. Because then the plants support each other and exchange e.g. B. Nutrients out.
Biotic Environment Factor: Human
A question that you may still ask yourself: Are we humans also a biotic factor? Basically yes. As a living being, human beings have a direct influence on other living beings. However, in animals these actions are natural, in humans they are not. Humans «intentionally» trigger both abiotic and biotic environmental factors.
To give you a few examples: Abiotic factors are e.g. B. influenced by the disposal of plastic in seas or lakes or by chemicals in wastewater. Biotic factors would z. B. affect the hunting of animals.
Biotic environmental factors – the most important
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biotic Environmental factors are, as the name suggests, influencers compared to abiotic environmental factors the living nature on an organism. To better break these down, there are a number of categories.
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For the first time, a distinction is made between primary and secondary biotic factors. Primary factors are effects that emanate directly from other organisms, while secondary factors describe the process when an abiotic factor is modified by a living being or organism.
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Among the biotic environmental factors, there is a set of biotic interactions that describe how living things in ecosystems get along with each other. This means symbiosis, competition and parasitism.
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A symbiosis occurs when two different species live together in a community and both benefit from it. Parasitism arises when only one of the two creatures in…