We explain what biotic factors are and how they are classified. Examples of biotic factors and how they relate to abiotic factors.
What are the biotic factors?
Biotic factors are all those that possess life, that is, that are contemplated in one of the kingdoms of life and whose interactions aim at the survival and reproduction of their species. In other words, biotic factors are all the living beings that are part of an ecosystem and all the interactions that occur between them. They usually refer to what is contemplated in the flora and fauna of a given environment, but they also include fungi and microorganisms.
Biotic factors are commonly organized in populations, that is, sets of individuals of the same species sharing a specific habitat. In turn, the populations of the same site interact with each other forming a community.
See also: Adaptation of living beings
Relationships between biotic factors
Sharing an environment results in the establishment of different types of relationships between biotic factors.
- between the same species:
- Competitive relationships (for food, space or other resources).
- Cooperative relationships (to protect themselves from predators, to orient themselves in migratory processes or to divide the work).
- between different species (interspecific)
- Competitive relationships for the same resources: food, light, space, humidity, etc.
- Relationships that cause harm to some of the species: predation, herbivory, parasitoidism.
- Relationships that involve obtaining a benefit for both: mutualism and symbiosis.
- Relationships in which one of the species involved obtains a benefit or harm while the other is neither favored nor harmed: commensalism and amensalism respectively.
The feeding relationships that occur between living beings that share a habitat are represented in trophic chains (or food chains) that reflect the flow of matter and energy in ecosystems.
Biotic factors are distinguished from abiotic factors in that the latter are inert, that is, they are not related to life but to the surrounding matter and their processes (chemical, climatic, physical, etc.) are non-organic. Abiotic factors are those that determine the physical environment in which living beings live.
Classification of biotic factors
Biotic factors can be classified into three types, depending on the way they feed and the place they occupy in food chains:
- Producing organizations. Also called autotrophs, these living beings are capable of producing their own food from inorganic matter and a source of energy. The producing organisms can be of two types:
- Photoautotrophs. They are those that make their food through photosynthesis, a process by which they synthesize sugars from carbon dioxide and water, taking advantage of light. For example: plants.
- Chemoautotrophs. They are those that obtain the energy to make their food from different exothermic chemical reactions of inorganic compounds. Unlike photoautotrophs, these organisms do not use water in the chemosynthesis process and do not produce oxygen. This group includes some bacteria that live in extreme environments.
- Consumer organizations. Also called heterotrophs, they are those living beings that need to feed on others, that is, they must consume organic matter to sustain their metabolism and they obtain it from other living beings. Consumers can be of two types:
- Herbivores. They are those that feed on productive organisms, for example, they eat plants, seeds, roots, algae or vegetables. This group includes everything from small animals, such as the rabbit, to large ones such as the giraffe.
- Carnivores. They are those that feed on other consumer organisms (herbivores or even other carnivores). This group includes everything from insects and arachnids to large mammals, such as the lion.
- Detritivores. Also called detritophages, they feed on detritus, which is dead organic matter. This includes corpses, leaf litter and feces. Within this group are protozoa, worms, mollusks, crustaceans, myriapods (such as millipedes) and a wide variety of insects such as beetles and flies.
- decomposer organisms. Also called saprotrophs, they are those living beings that supply themselves with energy from the organic matter present in the corpses and body remains of all members of the food chain, and carry out the process of “recycling” the matter and the energy. In general terms, they release simple molecules, such as carbon dioxide and mineral salts, which can be reused by producers. This group includes microbial heterotrophs such as bacteria, fungi and yeasts.
Examples of biotic factors
Some examples of biotic factors can be:
- The forests. They are large agglomerations of trees of different sizes and strata, which serve as habitat for many animals and supply constant organic matter to the soil detritus.
- Fungi and bacteria. They are two of the main types of decomposers, which obtain energy from dead organic matter (dead leaves, pieces of bark, remains of dead animals, shed skin, excrement) and assimilate all the nutrients present in it, leaving the rest available to producing organizations.
- The large predators. They are the big cats, snakes, birds of prey, that is, the large consumers of animal meat, which feed exclusively on smaller animals. They keep populations under control and eventually die, adding to the organic matter to be recycled.
- phytoplankton. Present only in aquatic environments, these are a variety of photosynthetic microorganisms, mostly floating algae and cyanobacteria, that form the basis of most aquatic food webs. They are food for larger organisms such as fish, crustaceans (krill) and even large animals such as whales.
- Good size herbivores. They are those that feed on tons of organic plant matter, which then serves as sustenance for the large predators and scavengers that will come later. Some large herbivores are oxen, antelopes, elephants and nus.
Biotic and abiotic factors
Biotic and abiotic factors are distinguished in that biotic factors have to do with life forms and their relationships, while abiotic factors relate to the physicochemical characteristics of an ecosystem. Thus, while animals and plants are biotic factors, Soil pH, climate and soil composition are abiotic factors.
However, both types of factors are strongly linked, since the state of one is reflected in that of the other. The chemical composition of the soil, for example, directly affects its fertility and, therefore, the ability to sustain plant life, which will in turn support consumers and detritophages. But the existence of these life forms will, over time, add layers of organic matter to the soil, keeping it fertile and rich in nutrients that in turn will fix its chemical composition.
In conclusion, we can affirm that biotic and abiotic factors are fundamental for the development of species and their habitat: it is not possible to conceive the existence of one without the other.
References
- Biology: Solomon E., Berg L., Martin D. (2013) 9th Edition. Cengage Learning Publishing.
- Ecology. Smith T and Smith R. (2007) 6to Edition. Pearson Education Publishing.
- Ecology I: Introduction. Organisms and populations. Escolásico León C., Cabildo Miranda M. del P., Claramunt Vallespí RM, Claramunt Vallespí T. (2013) Digital edition. National University of Distance Education.
