Every adult remembers from schoolbiology, what is symbiosis. Or at least heard that word. However, not everyone knows that the most common example of symbiosis is a couple of people - lactic acid bacteria. In essence, symbiosis is any form of relationship between two living organisms with a different genotype and origin, in which they coexist as a single system. However, one should not confuse symbiosis with parasitism, as it often happens.
In nature, there are the following types of symbiosis:the aforementioned parasitism (a type of relationship that is useful to one partner and harmful to another), mutualism (mutually beneficial relations), commensalism (relations beneficial for one partner and indifferent for another), and amenism (relations harmful to one side and indifferent for the second). In addition, in modern science, it is customary to isolate symbiogenesis or endosymbiosis, which is an intracellular symbiosis: one organism lives inside the cell of another. Organisms that are in symbiotic relationships are called symbionts.
Для того чтобы понять, что такое симбиоз, в First of all, it is necessary to consider its earliest form, namely, symbiogenesis. Scientists have shown that cellular organelles mitochondria and plastids were previously separate most ancient microorganisms: mitochondria were prokaryotic bacteria, and plastids were autotrophic bacteria that settled inside the simplest eukaryotic cells. Initially, they were characterized by a symbiosis of the type of mutualism, that is, a mutually beneficial relationship. Then these organisms merged so much that they became a single structure, which eventually became genetically fixed.
By the same principle all others are built.types of symbiotic relationships. The easiest way to imagine what a symbiosis is, using the classic example of lichens. This type of relationship should be regarded as mutualism, since the fungus receives the nutrients synthesized by the latter from cyanobacteria and, in turn, creates favorable environmental conditions for bacteria, protecting them from drying out, ultraviolet radiation and other adverse environmental factors, and also makes it possible on a substrate having an acidic pH.
Parasitism is also a type of symbiosis.A classic example of it is all eukaryotic pathogens of infectious diseases, including fungal infections. In such a relationship, the parasite lives in the body of the host, feeds on its resources. There are obligate (permanent) and optional (periodic) parasitism. The first are viruses, the second - lice, worms and others.
An example of mutualism is the human-intestinal microflora pair mentioned above.
In the framework of commensalism, it is customary to distinguishmany subspecies: zoo choria (distribution of parts of plants used for breeding with animals) are birds feeding on seeds or carrying them on their paws), sinoykia (using one organism of the other without harming the first, for example, fish laying eggs shells of mollusks). It should not be confused with inquinism - the use of the host’s home with the destruction of the latter, for example, insects, larvae moving away to mollusk shells or galls, while destroying the host’s organism.
The most common example of amensismare the relationship of the tree and the moss growing under it. The moss experiences a negative effect from such a symbiosis (lack of lighting, nutrients, water, etc.), and the tree is indifferent.
Thus, using fairly simple and vivid examples, it is easy to illustrate what symbiosis is and not to confuse mutualism with commensalism and parasitism.
