Biotic factors of nature are the relationships of all living organisms with each other and with the environment. Biotic connections arise in biogeocenosis between different species. The most basic and important form of these connections are food relationships, which form food cycles and complex chains.
Neutralism
Biotic connections, in which the vital activity of one organism does not have any effect on the life of another, is called neutralism. Examples of this relationship are the hare and the tapeworm, the urticating butterfly and the flea, and countless others.
Scientists have noticed that during their life all living organisms release solid, liquid and gaseous substances into the environment that can affect other plants, animals and microorganisms.
Allelopathy
Biotic connections, carried out due to specific active metabolic products released into the external environment, are called allelopathy.
This phenomenon has been known for a long time, but only in 1937 did the German scientist Molisch give it a specific name.
This phenomenon has been studied in more detail on plant organisms. The secretions of many plants can have both toxic and stimulating effects on nearby neighbors. Examples of biotic relationships in plants can be:
- absinthine leaves of bitter wormwood can inhibit the growth and development of many other plants;
- beans slow down the growth of spring wheat;
- excretion of couch grass roots not only affects other grasses and shrubs, but also trees.
Animals also secrete substances - pheromones that can influence the behavior and development of individuals of a certain species. They also transmit information to other species.
The release of biologically active substances is also characteristic of microorganisms. For example, antibiotics such as penicillin and streptomycin are widely known.
Group effect
Group effect is the optimization of all processes, which leads to the maximum increase in the viability of individuals when they live together. This feature is manifested in a large number of species that can normally reproduce and develop only if they have united in small or large groups.
Types of biotic relationships depend on the habitat of individuals and ways of their existence. For example, in order for a herd of African elephants to survive, it must contain at least thirty individuals.
Competition
Biotic bonds during which relationships occur between individuals of the same or different species, in whichthe use of the same resources with their significant shortage is called competition. Intraspecific competition can significantly increase the intensity of natural selection. The most popular example of such a process is the self-thinning of fir trees.
But the interspecific type of competition is most often characteristic of ecologically close individuals or populations of different species. It can be either passive or active. The first involves the use of natural resources necessary for both species. And during the second, one species is suppressed by another.
Competition is one of the main reasons why several species with similar lifestyles, behaviors and dietary habits cannot coexist in the same community. Such competition can turn into enmity.
Predation
Biotic relationships in nature, which are characterized by such a way of obtaining food as catching, killing and eating caught individuals, are called predation. The basis of such relationships are food links and food chains. The predator first kills the prey, and only then eats it. But before that, she needs to be caught. For these purposes, each predator has special adaptations. Historically, victims also have protective elements. For example, carapace, spines, spines, poison glands and protective coloration.
Thanks to such mutual adaptations, groupings of organisms were formed - predators and prey. Suchrelationships formed the principles of regulation of the number of both components.
Until recently, scientists thought that all predators are harmful inhabitants of the planet, so they need to be exterminated. However, this opinion turned out to be wrong. Such actions will have negative global consequences. There is a risk of damage not only to wildlife, but to the entire economy.
Symbiosis
Biotic bonds in nature, during which one of the partners (or both at once) benefits from the relationship with each other, is called symbiosis.
There are many examples of mutually beneficial symbiosis in the world. For example, gastric and intestinal bacteria, without which the process of digestion is impossible. Or the pollination of certain orchids, whose pollen can only be carried by certain types of insects. Such relationships are successful when they increase the likelihood of both partners to survive.
In other words, this is absolutely any form of relationship between organisms of different species (this includes parasitism - a special kind of relationship that is beneficial for one partner, but harmful to the other).
Symbiosis, which will be beneficial for both representatives, is called mutualism. But commensalism is a relationship that is beneficial to one, but indifferent to another. Endosymbiosis is the ability of one partner to live inside the cell of the other.
Mutualism
The most common form of cohabitation is mutualism. Biotic connections in nature (grade 9 of the school curriculum in detaildescribes this topic) in the form of mutualism put a prerequisite - the existence of both partners. During such a relationship, each of the partners receives its own benefit. For example, one partner uses the other as a source of food, and the second is protected from enemies or in favorable conditions for development and reproduction.
Each member of a mutualistic couple is selfish, and mutual benefit arises only from the fact that the benefit received outweighs all the costs that are required to maintain the relationship.
Mutually beneficial relationships are also formed through behavioral responses. Examples of biotic relationships of mutualism - birds combine their own food, and at the same time are seed distributors. Sometimes there are physical relationships.
Close contact of species during mutualism contributes to their joint evolution. An example of this is the adaptations that have evolved in flowers and their pollinators.
Commensalism
Biotic connections (grade 9) distinguish three types of commensalism:
- Use other types of food.
- Attached to another organism, which becomes a "host".
- They settle in the internal organs of the host.
Relationships of this type are very important for nature, as they make it possible for a large number of species to coexist on every piece of the Earth, as well as to maximize the development of the environment and use of food resources.
However, very often this type of connection goes into otherrelationships. When eating begins to harm the owner, then the relationship moves to a new level and becomes parasitism or competition.
Pasitism
Parasitism is a type of relationship in which the parasite uses the host as the main place of residence and source of food. Biotic connections (the table is presented in the article) describe this type of coexistence of individuals as follows: the parasite settles inside the host or on its surface. Parasitism can occur among various groups of organisms (plants, animals, fungi and humans).
The physiology of the parasite is subject to the life processes of the host. Therefore, for a productive existence, it is necessary to use biological resources. The longer coexistence occurs, the better this type of parasite adapts to its host and causes less harm to it.
