What is symbiosis in biology: definition

Symbiosis is any association between two various types populations. Its study is the quintessence of systems biology, which integrates not only all levels of biological analysis, from molecular to ecological, but also studies across the three domains of life. The development of this area is still at an early stage, but results will not be long in coming in the near future.

Types of symbiosis

What is symbiosis in biology (grade 5)? Symbiosis is a relationship between two or more organisms living in close contact with each other. An interaction occurs when two species live in the same place and one or both benefits from the other. Predation indirectly falls under this definition, since it can also be considered a type of symbiosis.

Mutualism

Mutualism is one of the most famous and most ecologically significant species symbiosis. In such relationships, for example, insects exist and such cooperation is favorable and mutually beneficial for both parties. Insects, birds and even some mammals obtain food in the form of nectar. The plant, on the other hand, gains a great reproductive advantage, namely the ability to transfer its pollen to other plants.

Since plants do not often end up together, it is quite problematic for them to perform the reproductive function without intermediaries. In this case, symbiosis is simply vital for them, and in the full sense of the word. Without pollinators, many plants might simply gradually disappear. On the other hand, without pollinating plants, many insects themselves would be in big trouble. This is truly a mutually beneficial alliance.

Biology doesn't stop there. Another fascinating form of beneficial cooperation can be seen in the relationship between some and aphids. Aphids are tiny, soft insects that feed on plant sap and produce a certain amount of sugar and water as waste. This becomes suitable food for some types of ants. In turn, the ants often move them to a new place, thus providing additional sources of food.

Commensalism

What is symbiosis in biology? First of all, this is cooperation. One of the rarest types of symbiosis found in nature is commensalism. In this case, only one party benefits. The second one is neither hot nor cold from such an arrangement. Finding examples of it is quite a difficult task. However, a few examples can be given.

An example of commensalism can be demonstrated by some desert lizards, which find a place of residence in abandoned rat or snake holes. Lizards receive shelter, while the other animal receives nothing in return.

What is symbiosis in biology? In simple words it can be said to be positive, negative or neutral cooperation between different types of organisms.

Symbiosis – man and bacteria: The human body is also part of this interconnected system. Evidence of this is how many beneficial bacteria work quietly and unnoticed in the human digestive tract. These bacteria promote digestion, form essential vitamins and repel enemy attacks. And man gives them shelter and food.

Symbiosis – animals, fungi, bacteria: In the animal world, such communities are also not uncommon. For example, in the multi-chambered stomach of ruminant animals: cows, sheep and deer, various bacteria, fungi and protozoa are present. These microorganisms break down the fiber in plant fibers to turn them into nutrients. Bacteria are involved in digestion and some insects that feed on fiber include beetles, cockroaches, silverfish, termites and wasps.

An example of symbiosis is bacteria in the soil: The soil is also full of living organisms. Bacteria (more than 500 billion), fungi (more than 1 billion) and multicellular organisms - from insects to worms (up to 500 million) can live in 1 kg of healthy soil. Many organisms process organic substances: animal excrement, fallen leaves, and others. The nitrogen that is released is necessary for plants, and the carbon they convert into carbon dioxide is required for photosynthesis.

Plant symbiosis: Peas, soybeans, alfalfa and clover live in close collaboration with bacteria and allow them to “infect” the root system. On the roots of leguminous plants, bacteria form nodules (bacteroides), where they settle. The job of these bacteroids is to convert nitrogen into compounds so that legumes can absorb them. And bacteria from leguminous plants receive the nutrition they need.

Fungi or mold are essential to the life of all trees, bushes and grasses. This interaction underground helps plants absorb moisture and minerals: phosphorus, iron, potassium, etc. And fungi feed on carbohydrates from plants, since they cannot produce their own food due to the lack of chlorophyll.

The orchid depends on fungi to a greater extent. To keep very small orchid seeds in wildlife could germinate, the help of fungi is required. Adult orchid plants have a rather weak root system, which is also supported by fungi - they form a powerful nutrition system. In turn, the fungi receive vitamins and nitrogen compounds from the orchid. But the orchid controls the growth of fungi: as soon as they grow and extend beyond the root to the stem, it inhibits their growth with the help of natural fungicides.

Symbiosis of insects and plants: Another example of symbiosis: bees and flowers. The bee collects nectar and pollen, and the flower needs pollen from other flowers to reproduce. After pollination occurs, there is no food for insects in the flower. How will they know about this? Flowers lose their scent, petals fall off, or color changes. And the insects fly to another place where there is still food for them.

Community of ants, plants, insects. For some ants, plants provide shelter and food. For this, the ants pollinate and distribute their seeds, supply them with nutrients and protect the plants from herbivorous mammals and other insects. The ants that settle in the thorns of the acacia save it from harmful climbing plants; they destroy them on their way when they “patrol” the territory, and the acacia treats them with sweet juice.

Other types of ants have their own “cattle farms” for breeding aphids. Aphids secrete sweet dew when ants lightly tickle them with their antennae. Ants feed aphids, milk them for food and protect them. At night, the ants drive the aphids into their nest for their safety, and in the morning they take them out to graze on young, succulent leaves. In one anthill there can be many thousands of “populations” of aphids.

Ants can also raise some types of butterflies when they are in the caterpillar stage. An example of the symbiosis of Myrmica ants and Arion blue butterflies. Complete your life cycle The butterfly cannot live without these ants. While in the ants' home in the caterpillar stage, the butterfly feeds them with sugary secretions. And having turned into a butterfly, it simply flies out of the anthill safe and sound.

Examples of symbiosis between birds and animals:
A long-eared owl brings a narrow-mouthed snake to its nest with its chicks. But the snake does not touch the chicks, it plays the role of a living vacuum cleaner - its food in the nest is ants, flies, other insects and their larvae. Chicks living with such a neighbor grow faster and are more durable.

And the bird, called the Senegalese avdot, is not friends with a snake, but with a Nile crocodile. And although crocodiles hunt birds, the avdotka makes her nest near its clutch and the crocodile does not touch it, but uses this bird as a sentry. When their nests are in danger, the avdotka immediately gives a signal, and the crocodile immediately hurries to defend its home.

In the sea fish kingdom there are also “cleanliness services”, in which cleaner shrimp and colorful gobies work. They rid fish of external bacteria and fungi, remove damaged and diseased tissue, as well as adherent crustaceans. Large fish are sometimes served by a whole team of such cleaners.

Symbiosis of fungus and algae. On tree trunks or on stones, on the backs of living insects you can see growths of gray or Green colour called lichens. And there are about 20 thousand species. What is a lichen? This is not a single organism, as it might seem, it is a mutually beneficial partnership between a fungus and an algae.

What do they have in common? Since fungi do not produce their own food, they entangle algae with their microscopic threads and absorb the sugars they produce through photosynthesis. And the algae receive the necessary moisture from the mushrooms, as well as protection from the scorching sun.

Symbiosis of algae and polyps. Coral reefs are a miracle of symbiosis between algae and polyps. Algae completely covers the polyps, making them especially colorful. Algae often weigh 3 times more than polyps. Therefore, corals can be attributed more likely to flora than to an animal. Through photosynthesis, algae produce organic substances, 98% of which they give to polyps, which feed on them and build the reef-forming calcareous skeleton.

For algae, this symbiosis has double benefits. Firstly, the waste products of polyps: carbon dioxide, nitrogen compounds and phosphates serve as food for them. Secondly, a strong calcareous skeleton protects them. Since algae need sunlight, Coral reefs grow in clean and sunlit waters.

So, we understand that mutualism, one of the main types of symbiosis, is a widespread form of mutually beneficial cohabitation, when the existence of each of them depends on the obligatory presence of a partner. Although each partner acts selfishly, the relationship becomes beneficial to them if the benefits received are greater than the costs required to maintain the relationship.

Can only spread one specific type of insect. Such relationships are always successful when they increase the chances of survival for both partners. The actions carried out during symbiosis or the substances produced are essential and irreplaceable for the partners. In a generalized sense, such symbiosis is an intermediate link between interaction and fusion.

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

The science of symbiosis is symbiology.

Mutualism

Mutually beneficial relationships can be formed based on behavioral reactions, for example, as in birds that combine their own feeding with the dispersal of seeds. Sometimes mutualistic species enter into close physical interaction, as in the formation of mycorrhiza (fungal roots) between fungi and plants.

Close contact of species during mutualism causes their joint evolution. A typical example is the mutual adaptations that have formed in flowering plants and their pollinators. Mutualistic species often disperse together.

Commensalism

Depending on the nature of the relationship between commensal species, three types are distinguished:

• the commensal is limited to using the food of an organism of another species (for example, in the convolutions of the shell of a hermit crab, an annelid worm of the genus Nereis lives, feeding on the remains of the cancer’s food);
• The commensal attaches itself to an organism of another species, which becomes the “host” (for example, a fish that sticks with its suction fin attaches to the skin of sharks, etc. large fish, moving with their help);
• commensal settles in internal organs host (for example, some flagellates live in the intestines of mammals).

An example of commensalism is legumes (for example, clover) and cereals growing together on soils poor in available nitrogen compounds, but rich in potassium and phosphorus compounds. Moreover, if the cereal does not suppress the legume, then it, in turn, provides it with an additional amount of available nitrogen. But such relationships can only continue as long as the soil is poor in nitrogen and the cereals cannot grow much. If, as a result of the growth of legumes and the active work of nitrogen-fixing nodule bacteria, a sufficient amount of nitrogen compounds accessible to plants accumulates in the soil, this type of relationship is replaced by competition. The result, as a rule, is the complete or partial displacement of less competitive legumes from the phytocenosis. Another variant of commensalism: unilateral assistance of a “nanny” plant to another plant. Thus, birch or alder can be a nanny for spruce: they protect young spruce trees from direct sun rays, without which a spruce cannot grow in an open place, and also protect the seedlings of young fir trees from being squeezed out of the soil by frost. This type of relationship is typical only for young spruce plants. As a rule, when a spruce tree reaches a certain age, it begins to behave like a very strong competitor and suppresses its nannies.
Shrubs from the families Lamiaceae and Asteraceae and South American cacti have the same relationships. Possessing a special type of photosynthesis (CAM metabolism), which occurs during the day with closed stomata, young cacti become very overheated and suffer from direct sunlight. Therefore, they can only develop in the shade under the protection of drought-resistant shrubs. There are also numerous examples of symbiosis that is beneficial for 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 pineapple, for example) live on tree branches but get their nutrients from the air. These plants use the tree for support without depriving it of nutrients. Plants make their own nutrients rather than getting them from the air.

Commensalism is a way of living together between two different types living organisms in which one population benefits from the relationship, while the other receives neither benefit nor harm (for example, silverfish and humans).

Symbiosis and evolution

In addition to the nucleus, eukaryotic cells have many isolated internal structures called organelles. Mitochondria, a single type of organelle, generate energy and are therefore considered the powerhouses of the cell. Mitochondria, like the nucleus, are surrounded by a double-layer membrane and contain DNA. On this basis, a theory of the emergence of eukaryotic cells as a result of symbiosis has been proposed. One of the cells absorbed the other, and then it turned out that together they cope better than separately. This is the endosymbiotic theory of evolution.
This theory easily explains the existence of a two-layer membrane. The inner layer originates from the membrane of the absorbed cell, and the outer layer is part of the membrane of the absorbed cell, wrapped around the alien cell. The presence of mitochondrial DNA is also well understood - it is nothing more than remnants of the DNA of the alien cell. So, many (perhaps all) organelles of a eukaryotic cell at the beginning of their existence were separate organisms, and about a billion years ago they joined forces to create a new type of cell. 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 the coexistence of different types of living organisms. At the dawn of evolution, symbiosis was the engine that brought together single-celled organisms one species into one multicellular organism (colony) and became the basis for the diversity of modern flora and fauna.

Examples of symbioses

• Endophytes live inside the plant, feed on its substances, releasing compounds that promote the growth of the host organism.
• Transport of plant seeds by animals, which eat the fruit and excrete the undigested seeds in droppings elsewhere.

Insects/plants

Mushrooms/algae

• A lichen consists of a fungus and an alga. The algae, through photosynthesis, produces organic substances (carbohydrates) that are used by the fungus, which supplies water and minerals.

Animals/Algae

Mushrooms/plants

• Many fungi obtain nutrients from the tree and supply it with minerals(mycorrhiza).

Insects/insects

• Some ants protect (“graze”) aphids and receive from them in return secretions containing sugar.

see also

Notes

Literature

• Margelis L. The role of symbiosis in cell evolution. - M: Mir, 1983. - 354 p.
• Douglas A.E. Symbiotic interaction. - Oxford University. Press: Oxford:Y-N, Toronto, 1994. - 148 p.

Links

Wikimedia Foundation. 2010.

- (from the Greek symbiosis cohabitation), close cohabitation of organisms of two or more species, which, as a rule, has become necessary and beneficial for both partners (symbionts). Symbiosis in marine animals was discovered by K. Mobius (1877). According to the degree of connection... Ecological dictionary

symbiosis- a, m. symbiose f. gr. symbiosis biol. Cohabitation of organisms of different species, usually bringing them mutual benefit, e.g. a fungus and an algae that together form a lichen. SIS 1954. Symbiosis of hermit crab and sea anemone. BAS 1. Vinogradov performed... ... Historical Dictionary of Gallicisms of the Russian Language

Symbiosis. Examples of symbiotic relationships

Symbiosis is a long-term cohabitation of organisms of two or more different species of plants or animals, when their relationship with each other is very close and usually mutually beneficial. Symbiosis provides these organisms with better nutrition. Thanks to symbiosis, it is easier for organisms to overcome the adverse effects of the environment.

Mutualism

Mutualism is a form of symbiosis in which the presence of each of the two species becomes obligatory for both, each of the cohabitants receives relatively equal benefits, and the partners (or one of them) cannot exist without each other.

A typical example of mutualism is the relationship between termites and flagellated protozoa that live in their intestines. Termites eat wood, but they do not have enzymes to digest cellulose. Flagellates produce such enzymes and convert fiber into sugars. Without protozoa - symbionts - termites die of starvation. In addition to a favorable microclimate, the flagellates themselves receive food and conditions for reproduction in the intestines.

An example of mutualism is the symbiosis of clown fish with sea anemones. First, the fish lightly touches the sea anemone, allowing it to sting itself and finding out the exact composition of the mucus with which the sea anemone is covered - this mucus is needed by the sea anemone so that it does not sting itself. Next, the clown fish reproduces this composition and after that it can hide from enemies among the tentacles of the sea anemone. The clown fish takes care of the sea anemone - it ventilates the water and carries away undigested food debris. The fish never move far from “their” sea anemone. The males drive the males away from her, the females drive the females away. Territorial behavior apparently caused the contrasting coloration.

Mutualism should be “hard” or “soft”. In the first case, cooperation is vitally important for both partners (they are connected by co-adaptation relations); in the second, the relations are more or less optional (this is usually called proto-cooperation).

Commensalism

Commensalism is a way of coexistence of two different species of living organisms, in which one population benefits from the relationship, while the other receives neither benefit nor harm.

Taking into account the dependence on the nature of the relationships between commensal species, three types are distinguished:

‣‣‣ the commensal is limited to using the food of an organism of another species (for example, an annelid worm from the genus Nereis lives in the convolutions of the shell of a hermit crab, feeding on the remains of the cancer’s food);

‣‣‣ a commensal attaches to an organism of another species, which becomes a “host” (for example, a fish that sticks with a suction cup fin attaches to the skin of sharks, etc.
Posted on ref.rf
large fish, moving with their help);

‣‣‣ The commensal settles in the internal organs of the host (for example, some flagellates live in the intestines of mammals).

An example of commensalism is legumes (for example, clover) and cereals growing together on soils poor in available nitrogen compounds but rich in potassium and phosphorus compounds. Moreover, if the cereal does not suppress the legume, then it, in turn, provides it with an additional amount of available nitrogen. But such relationships can only continue as long as the soil is poor in nitrogen and the cereals cannot grow much. If, as a result of the growth of legumes and the active work of nitrogen-fixing nodule bacteria, a sufficient amount of nitrogen compounds accessible to plants accumulates in the soil, this type of relationship is replaced by competition. The result, as a rule, is the complete or partial displacement of less competitive legumes from the phytocenosis.

Another variant of commensalism: unilateral assistance of a “nanny” plant to another plant. Thus, birch or alder act as a nanny for spruce: they protect young spruce trees from direct sunlight, without which spruce cannot grow in an open place, and also protect the seedlings of young fir trees from being squeezed out of the soil by frost. This type of relationship is typical only for young spruce plants. As a rule, when a spruce tree reaches a certain age, it begins to behave like a very strong competitor and suppresses its nannies.

Shrubs from the families Lamiaceae and Asteraceae and South American cacti have the same relationships. Possessing a special type of photosynthesis (CAM metabolism), which occurs during the day with closed stomata, young cacti become very overheated and suffer from direct sunlight. For this reason, they can only develop in the shade under the protection of drought-resistant shrubs. There are also numerous examples of symbiosis that is beneficial for 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. Likewise, plants called bromeliads (which include pineapple, for example) live on tree branches but get their nutrients from the air. These plants use the tree for support without depriving it of nutrients. Plants make their own nutrients rather than getting them from the air.

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

Symbiosis. Examples of symbiotic relationships - concept and types. Classification and features of the category "Symbiosis. Examples of symbiotic relationships" 2017, 2018.

What is Symbiosis

Symbiosis is a biological term used to define a beneficial relationship between two or more living organisms of different species. In addition to its use in biology, given word It is also used in other spheres of life to describe any mergers involving the receipt of benefits.

What is SYMBIOSIS - definition and concept in simple words.

In simple words, Symbiosis is a form of interaction between several organisms in which either one or all of them benefit. As a rule, the motivational factor for creating symbiotic relationships in nature is the simplest needs, such as nutrition, protection, habitat and reproduction. For example, fish stick to larger marine predators, thereby providing themselves with protection and nutrition in the form of leftovers from their prey. There are a huge number of similar examples of interaction, and we will talk about them in more detail a little later.

If we step back from biological terminology, the word “symbiosis” can be heard in the field of business, art, technology, politics, and so on. For example, quite often in the media you can hear a formulation like: “symbiosis of business and politics,” which literally means close interaction between political circles and business.

Types, forms and types of symbiosis.

IN general outline Symbiotic relationships can be divided into the following criteria:

Mutualism is symbiosis in which organisms benefit each other. Similar view“union” is the most common in nature and can be either optional or obligatory for different species. With such symbiosis, species can interact both physically and biochemically. For example, birds and insects that feed on flower nectar have a symbiotic relationship with these flowers. They receive nectar in the form of food, and in return they help with pollination by transferring pollen from one flower to another. Similarly, sea anemone and clown fish are in symbiosis, protecting each other from their enemies.

Commensalism is a relationship between species that benefits one organism without significantly harming or helping another. The above example with sticky fish relates to this type of connection.

Symbiosis examples.

An amazing example of a slightly creepy, but very interesting symbiosis is the relationship between the Cordyceps mushroom and insects. For example, zombie fungus spores attach to an ant and penetrate its tissue using enzymes. After this, the fungus changes the ant's behavior and subdues it. The ant moves away from its colony, climbs up the trunk of the plant and unnaturally places its mandibles deep into the leaf. After attaching to the leaf, the ant loses the ability to move and the fungus begins to grow from its body. Thus, being at altitude, the zombie mushroom spreads its spores most effectively.