What is symbiosis. Ecological Dictionary What is symbiosis, what does it mean and how to spell it correctly

Health 29.08.2019

Health

From συμ- - jointly + βίος - life) - a form of relationship in which both partners or only one benefits from the other.

Found in nature wide range examples mutually beneficial symbiosis(mutualism). From stomach and intestinal bacteria, without which digestion would be impossible, to plants (an example is some orchids, whose pollen can only be spread by one, certain kind insects). Such relationships are always successful when they increase the chances of both partners to survive. The actions carried out in the course of symbiosis or the substances produced are essential and irreplaceable for the partners. In a generalized sense, such a symbiosis - intermediate between interaction and fusion.

This theory easily explains the existence of a bilayer membrane. The inner layer originates from the membrane of the engulfed cell, while the outer layer is part of the membrane of the engulfed cell wrapped around the alien cell. It is also well understood that the presence of mitochondrial DNA is nothing more than remnants of the alien cell's DNA. So, many of the organelles of the eukaryotic cell at the beginning of their existence were separate organisms, and about a billion years ago they combined their efforts to create cells of a new type. Therefore, our own bodies are an illustration of one of the oldest partnerships in nature.

It should also be remembered that symbiosis is not only coexistence different types living organisms. At the dawn of evolution, symbiosis was the engine that brought unicellular organisms of the same species into one multicellular organism (colony) and became the basis for the diversity of modern flora and fauna.

Photo of symbiosis of mushrooms with roots

A striking example of the symbiosis of fungi is mycorrhiza - the community of fungi and higher plants (various trees). With such “cooperation”, both the tree and the mushroom win. Settling on the roots of a tree, the fungus will perform the function of absorbing root hairs, and helps the tree to absorb nutrients from the soil. With such a symbiosis, the fungus receives ready-made organic substances (sugars) from the tree, which are synthesized in the leaves of the plant with the help of chlorophyll.

In addition, during the symbiosis of fungi and plants, the mycelium produces substances such as antibiotics that protect the tree from various pathogenic bacteria and pathogenic fungi, as well as growth stimulants such as gibberellins. It is noted that the trees under which grow hat mushrooms practically do not get sick. In addition, the tree and mushroom actively exchange vitamins (mainly B and PP groups).

Many cap mushrooms form symbiosis with the roots of various plant species. Moreover, it has been established that each type of tree is able to form mycorrhiza not with one type of fungus, but with dozens of different species.

In the photo Lichen

Another example of the symbiosis of lower fungi with organisms of other species are lichens, which are an alliance of fungi (mainly ascomycetes) with microscopic algae. What is the manifestation of the symbiosis of fungi and algae, and how does such “cooperation” take place?

Until the middle of the 19th century, it was believed that lichens are separate organisms, but in 1867, Russian botanists A. S. Famintsyn and O. V. Baranetsky established that lichens are not separate organisms, but a commonwealth of fungi and algae. Both symbiotes benefit from this union. With the help of chlorophyll, algae synthesize organic substances (sugars), which the mycelium feeds on, and the mycelium supplies the algae with water and minerals that it sucks out of the substrate, and also protects them from drying out.

Thanks to the symbiosis of the fungus and algae, lichens live in places where neither fungi nor algae can exist separately. They inhabit sultry deserts, highlands and harsh northern regions.

Lichens are even more mysterious creatures of nature than mushrooms. They change all the functions that are inherent in separately living fungi and algae. All vital processes in them proceed very slowly, they grow slowly (from 0.0004 to several mm per year), and age just as slowly. These unusual creatures are very different long duration life - scientists suggest that the age of one of the lichens in Antarctica exceeds 10 thousand years, and the age of the most common lichens that are found everywhere is at least 50-100 years.

Lichens, thanks to the community of fungi and algae, are much more hardy than mosses. They can live on substrates on which no other organism on our planet can exist. They are found on stone, metal, bones, glass and many other substrates.

Lichens still continue to amaze scientists. They found substances that no longer exist in nature and which became known to people only thanks to lichens (some organic acids and alcohols, carbohydrates, antibiotics, etc.). The composition of lichens, formed by the symbiosis of fungi and algae, also includes tannins, pectins, amino acids, enzymes, vitamins and many other compounds. They accumulate various metals. Of the more than 300 compounds contained in lichens, at least 80 of them are not found anywhere else in the living world of the Earth. Every year, scientists find new substances in them that are not found in any other living organisms. Currently, more than 20 thousand species of lichens are already known, and every year scientists discover several dozen new species of these organisms.

This example shows that symbiosis is not always a simple cohabitation, and sometimes gives rise to new properties that none of the symbionts had separately.

There are many such symbioses in nature. With such a commonwealth, both symbionts win.

It has been established that the desire for association is most developed in mushrooms.

Mushrooms enter into symbiosis with insects. An interesting commonwealth is the relationship of some types of mold fungi with leaf-cutting ants. These ants specially breed mushrooms in their dwellings. In separate chambers of the anthill, these insects create entire plantations of these mushrooms. They specially prepare the soil on this plantation: they bring in pieces of leaves, grind them, “fertilize” with their feces and the feces of caterpillars, which they specially keep in the neighboring chambers of the anthill, and only then bring the smallest hyphae of fungi into this substrate. It has been established that ants breed only mushrooms of certain genera and species, which are not found anywhere in nature, except for anthills (mainly fungi of the genera Fusarium and Hypomyces), and each species of ants breeds certain types of mushrooms.

Ants not only create a mushroom plantation, but also actively care for it: they fertilize, cut and weed. They cut off the fruiting bodies that have appeared, preventing them from developing. In addition, ants bite off the ends of fungal hyphae, as a result of which proteins accumulate at the ends of the bitten hyphae, and swells are formed that resemble fruiting bodies, which the ants then feed on and feed their babies. In addition, when the hyphae are cut, the mycelium of the fungi begins to grow faster.

"Weeding" is as follows: if mushrooms of other species appear on the plantation, the ants immediately remove them.

Interestingly, when creating a new anthill, the future queen, after the mating flight, flies to a new place, begins to dig passages for the dwelling of her future family, and creates a mushroom plantation in one of the chambers. She takes mushroom hyphae from an old anthill before the flight, placing them in a special under-mouth bag.

Usually, symbiosis is mutualistic, that is, the cohabitation of both organisms (symbionts) is mutually beneficial and arises in the process of evolution as one of the forms of adaptation to the conditions of existence. Symbiosis can be carried out both at the level of multicellular organisms and at the level of individual cells (intracellular symbiosis). Plants with plants, plants with animals, animals with animals, plants and animals with microorganisms, microorganisms with microorganisms can enter into symbiotic relationships. The term "symbiosis" was first introduced by the German botanist A. de Bari (1879) as applied to lichens. A striking example of symbiosis among plants is mycorrhiza - the cohabitation of fungal mycelium with roots. higher plant(hyphae braid the roots and contribute to the flow of water and minerals from the soil into them); some orchids cannot grow without mycorrhiza.

Nature knows numerous examples of symbiotic relationships from which both partners benefit. For example, for the nitrogen cycle in nature, the symbiosis between leguminous plants and soil bacteria Rhizobium. These bacteria - they are also called nitrogen-fixing - settle on the roots of plants and have the ability to "fix" nitrogen, that is, to break down strong bonds between the atoms of atmospheric free nitrogen, making it possible to incorporate nitrogen into plant-available compounds, such as ammonia. AT this case the mutual benefit is obvious: the roots are the habitat of bacteria, and the bacteria supply the plant with essential nutrients.

There are also numerous examples of symbiosis that is beneficial to one species and does not bring any benefit or harm to another species. For example, the human intestine is inhabited by many types of bacteria, the presence of which is harmless to humans. Similarly, plants called bromeliads (which include, for example, pineapple) live on the branches of trees, but get their nutrients from the air. These plants use the tree for support without depriving it of nutrients.

A type of symbiosis is endosymbiosis, when one of the partners lives inside the cell of the other.

The science of symbiosis is symbiology.

Symbiosis is a form of relationship in which both organisms benefit from each other. In other words, it is a mutually beneficial cohabitation. An organism that lives in symbiosis is a symbiont.

Types of symbiosis

In biology, the term symbiosis can be used in two ways. different meanings. As already mentioned, this is a form of cohabitation that benefits everyone. However, in biology there is an older definition - mutualism. In any case, the word "symbiosis" was introduced in 1879 by the German botanist and microbiologist Heinrich Anton de Bary. The term meant as a profitable existence different organisms whether it is beneficial to them or not. The symbiosis is divided into:

The third type denoted symbiosis, from which one organism benefited, and for the second it had a neutral meaning. This type of cohabitation can be divided into: zoochory (animals and plants interact, animals help plants transfer seeds and fruits), synoikia (lodging, one is indifferent, the other is beneficial), phoresia (a symbiosis of different species, in which a larger symbiont wears a smaller one) , epibiosis (settlement of one organism on another), epioikia (a symbiont lives on the surface of another without harming it), entoikia, paroikia. However, all these species have one similarity: one of the symbionts forms a special form of habitat for the other.

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Examples of symbiosis

mushrooms and trees

Many mushrooms ( porcini, boletus) have a close relationship with the roots of trees, having benefits both for themselves and for the plant. With such a symbiosis, the small roots of certain trees are braided with mycelium threads (hyphae), penetrating the roots and located between the cells. This formation is called mycorrhiza. Mycorrhiza was discovered by the Russian botanist Franz Mikhailovich Kamensky in 1879, and the German scientist David Albertovich Frank gave the name to this type of symbiosis.

In which both partners benefit from the other.

In nature, there is a wide range of examples of mutually beneficial symbiosis (mutualism). From stomach and intestinal bacteria, without which digestion would be impossible, to plants (an example is some orchids, whose pollen can only be distributed by one, certain type of insect). Such relationships are always successful when they increase the chances of both partners to survive. The actions carried out in the course of symbiosis or the substances produced are essential and irreplaceable for the partners. In a generalized sense, such a symbiosis is an intermediate link between interaction and merging.

It should also be remembered that symbiosis is not only the coexistence of different types of living organisms. At the dawn of evolution, symbiosis was the engine that brought unicellular organisms of the same species into one multicellular organism (colony) and became the basis for the diversity of modern flora and fauna.

Examples of symbiosis

Endophytes live inside the plant, feed on its substances, while releasing compounds that promote the growth of the host organism.
Transportation of plant seeds by animals that eat the fruit and excrete the undigested seeds along with the droppings elsewhere.

insects/plants

mushrooms/algae

A lichen is composed of a fungus and an algae. As a result of photosynthesis, algae produce organic substances (carbohydrates) that are used by the fungus, which supplies water and minerals.