Biotic factors of nature are the relationships of all living organisms with each other and with the environment. Biotic connections arise in the biogeocenosis between different species. The most basic and important form of such relationships are nutritional relationships that form nutrition cycles and complex chains.
Neutralism
Biotic connections in which the vital activity of one organism has no effect on the life of another is called neutralism. Examples of this relationship are the hare and the tapeworm, the hive butterfly and the flea, as well as an infinite number of 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 due to specific active metabolic products released into the 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 definite name.
This phenomenon has been studied in more detail on plant organisms. The excretion of many plants can have both toxic and stimulating effects on nearby neighbors. Examples of biotic relationships in plants may be:
- absintin of bitter wormwood leaves can inhibit the growth and development of many other plants;
- beans slows the growth of spring wheat;
- isolation of wheatgrass roots has a bad effect not only on other herbs and shrubs, but also on trees.
Animals also secrete substances - pheromones, which can influence the behavior and development of individuals of a certain species. With their help, information is also transmitted to other species.
The selection of biologically active substances is also characteristic of microorganisms. For example, antibiotics such as penicillin and streptomycin are widely known.
Group effect
The 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 manifests itself in a large number of species that can multiply and develop normally only if they are combined into small or huge groups.
Types of biotic relationships depend on the habitat of individuals and their mode of existence. For example, in order for a herd of African elephants to survive, there must be at least thirty individuals in it.
Competition
Biotic connections during which relationships occur between individuals of the same or different species, in which the same resources are used with a significant lack of them, are called competition. Intraspecific competition can significantly increase the intensity of natural selection. The most popular example of such a process is spruce self-cutting.
But the interspecific type of competition is most often characteristic of ecologically close individuals or populations of different species. It can be both passive and active. The first involves the use of natural resources needed by both species. And during the second, one species is suppressed by another.
Competition is one of the main reasons that several species, characterized by similar lifestyles, behaviors and dietary patterns, cannot cohabit in one community. Such competition can turn into enmity.
Predation
Biotic connections in nature, which are characterized by such a method of obtaining food as catching, killing and eating caught individuals, are called predation. The basis of such relationships are nutritional relationships 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 devices. Historically, victims also have protective elements. For example, shell, thorns, spikes, poisonous glands and protective coloring.
Thanks to such mutual adaptations, the groupings of organisms - predators and victims - were formed. In such relationships, the principles of regulating the abundance of both components are formed.
Until recently, scientists thought that all predators are harmful inhabitants of the planet, so they need to be exterminated. However, this opinion was erroneous. Such actions will have negative global consequences. There is a risk of damage not only to wildlife, but to the entire household.
Symbiosis
Biotic connections in nature, during which one of the partners (or both at once) benefits from relationships with each other, are called symbiosis.
In the world there are a large number of examples of mutually beneficial symbiosis. For example, gastric and intestinal bacteria, without which the digestion process is impossible. Or pollination of some orchids, whose pollen can only be carried by a certain type of insect. Such relationships are successful when they increase the likelihood of both partners surviving.
In other words, this is absolutely any form of relationship between organisms of different species (this includes parasitism - a special type of relationship that is beneficial for one partner, but harmful for another).
The symbiosis that will be beneficial for both representatives is called mutualism. But commensalism is a relationship that is useful to one, but indifferent to the other. Endosymbiosis is the ability of one partner to live inside the cell of another.
Mutualism
Mutualism is considered the most common form of cohabitation. Biotic connections in nature (the 9th grade of the school curriculum describes this topic in detail) in the form of mutualism set a prerequisite - the existence of both partners. During such a relationship, each of the partners gets its own benefit. For example, one partner uses the other as a power source, and the second is protected from enemies or in favorable conditions for development and reproduction.
Each participant in a mutualistic couple is an egoist, 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 connections of mutualism - birds combine their own nutrition, and at the same time they are the distributors of seeds. Sometimes physical relationships arise.
Close contact of species under mutualism contributes to their joint evolution. An example is the devices that have formed 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 the "master".
- Settled in the internal organs of the host.
Relations of this type are very important for nature, as they provide an opportunity to cohabit a large number of species on each piece of the Earth, as well as maximize the environment and use food resources.
However, very often this type of connection goes into other relationships. When eating begins to harm the owner, the relationship goes to a new level and becomes parasitism or competition.
Parasitism
Parasitism is a type of relationship in which the parasite uses the host as the main place of residence and source of nutrition. 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 (in plants, animals, fungi and humans).
The physiology of the parasite is subject to the host's life processes. Therefore, for a productive existence, it is necessary to use biological resources. The longer coexistence takes place, the better this type of parasite adapts to its host and does less harm to it.