What is competition in biology examples. Types of interspecies relationships

Intraspecific competition has its own characteristics. The reason for its occurrence is a typical situation when the resource for which the individuals of the population are fighting is quantitatively limited. There is fierce competition (for territory, food resources, etc.), which is observed at a high population density.

Another form of intraspecific competition is rivalry, when one individual does not allow another to occupy an existing territory and use its resources. In this case, a form of ideal or uncompromising competition is possible, which is decided by emigration to other territories.

The severity of competition and its impact on the population depends on the density, which determines the frequency and intensity of contacts between competitors.
Intraspecific competition not only impoverishes resources and thereby leads to increased mortality, stunted growth of individuals, it encourages self-aggression, cannibalism, and reduces the potential contribution of an individual to the next generation and population development.
Intraspecific competition between individuals of a population in plants can be characterized as a struggle for light, heat, moisture, and the area of ​​mineral nutrition. In this competition, organisms that are nearby are more developed, displacing the weak completely or strongly suppressing their development and leading to gradual death. That is why, in agrophytocenoses, in order to reduce competition and create optimal conditions for the growth and development of cultivated plants, the density of individuals and the area of ​​their mineral nutrition are regulated by the appropriate type of sowing or thinning of crops, the destruction of weeds and the selection of biologically compatible species for mixed crops.

In natural plant populations, self-recovery takes place - a decrease in the number of individuals per unit area.
This phenomenon is known to foresters. The number of trees per unit area decreases with the age of the stands. The liquefaction of the forest stand occurs the faster, the more photophilous the species and the better environmental conditions. The latter is associated with an increase in the growth rate in good conditions and, accordingly, an increase in its needs, from which competition becomes intense (Fig. 9.2).

Each species has its own optimal density, i.e. such a degree of saturation of the territory of the population with its individuals, which ensures the best reproduction and the greatest stability of the population, reduces the severity of competition.

In animals of different species, too, in the process of evolution, appropriate adaptive adaptations have been developed for life in an environment that is sparsely saturated or densely populated with individuals.
Appropriate biological properties and a life strategy have been developed that enable organisms to reproduce and survive in a “competitive vacuum” (lack or little competition). In the first case, small animals can breed, their descendants will survive, although the population density will be high.

In the second case, large animals and relatively similar descendants can compete for space and food. Therefore, the main energy of organisms is directed to competition, to increase their survival, to produce competitive offspring.

These tendencies and strategies of different species are reflected in two opposite types of natural selection: r-selection and k-selection, discussed in chapter 2.
Intraspecific competition between plant individuals of the same population can be calculated using the Yoda equation. According to this equation, the average area per individual (a) is inversely proportional to the population density (d).

Competition(from late Latin concurentia - collide), a type of relationship between organisms of the same or different species competing for the same environment resources(sexual partners, food, territory, shelters, etc.) with a lack of the latter. Intraspecific competition is considered as the most important form of the struggle for existence, since potentially the most acute competitive relations arise between more similar individuals. For example, in mammals, competition between males for possession of a female during the breeding season is expressed in a vivid form. During the rut, males of many species ( deer, rams, bears) arrange fierce tournament fights.

Competition for territory, shelters and food is most fully expressed in territorial species with a solitary lifestyle (some mouse-like rodents, mole rats, predatory mammals). However, in nature there are mechanisms (environmental, behavioral, etc.) that reduce the intensity of intraspecific competition. For example, many aggressive actions of animals during mutual contacts are ritualized and are intended, first of all, to intimidate the enemy, not bringing the contact to physical interaction.

Interspecific competition is more often observed between individuals of ecologically close species that use the same habitats and food resources. Such functionally similar groups of species that interact strongly with each other and weakly with other types of biocenosis are often distinguished in guilds (the term was proposed by R. B. Root in 1967). The idea of ​​guilds is closely related to the ecological niche model.

Competition can be passive (indirect), through the consumption of environmental resources necessary for both species, and active (direct), accompanied by the suppression of one species by another. The first option is often called operational competition, and the second - interference. An example of active competition is the relationship between acclimatized American and native European minks, in which the native view turned out to be uncompetitive.

The state of competition in the long term is not energetically beneficial for both competitors, therefore, various mechanisms are implemented in nature that reduce the intensity of interspecific competitive relations, based, in particular, on the division of resources and the formation of different ecological niches. The result of the action of intraspecific and interspecific competition, as a rule, is different (see also Speciation). The first leads to the culling of the least competitive (least adapted) individuals and, under conditions of an unchanged environment, to a narrowing of the rate of reaction of the species, specialization (stabilizing selection; see below). Natural selection), and under conditions of a directionally changing environment - to a shift in the reaction rate in the direction determined by the changing environment, i.e., to the emergence of a new adaptive form (driving selection; see Natural selection).

intraspecific competition

Interspecific competition leads to further divergence of species due to the culling of morphs with similar requirements.

Natural selection), and in a directionally changing environment - to a shift in the reaction rate in the direction determined by the changing environment, i.e., to the emergence of a new adaptive form (driving selection; see Natural selection). Interspecific competition leads to further divergence of species due to the culling of morphs with similar requirements.

In natural communities, animals of the same and different species live together and interact with each other. In the process of evolution, certain relationships are developed between animals, reflecting the connections between them. Each species of animal performs a specific role in the community in relation to other living organisms.

The most obvious form of relationship between animals is predation. In natural communities, there are herbivores that feed on vegetation, and there are carnivores that catch and eat other animals. In relationships, herbivores act victimsami, and carnivores - predatorami. At the same time, each prey has its own predators, and each predator has its own "set" of victims.

INTRA-SPECIES COMPETITION

So, for example, lions hunt zebras, antelopes, but not elephants and mice. Insectivorous birds catch only certain types of insects.

Predators and prey have evolved to adapt to each other so that some have developed body structures that allow them to catch as best as possible, while others have such a structure that allows them to better run or hide. As a result, predators catch and eat only the weakest, sickest and least adapted animals.

Carnivores do not always eat herbivores. There are predators of the second and third order, which eat other predators. This is often found among aquatic inhabitants. So some species of fish feed on plankton, the second - on these fish, and a number of aquatic mammals and birds eat the latter.

Competition- a common form of relationships in natural communities. Usually, competition is most acute between animals of the same species living in the same territory. They have the same food, the same habitats. Between animals of different species, the competition is not so sharp, since their lifestyles and needs are somewhat different. So the hare and the mouse are herbivores, but they eat different parts of plants and lead a different lifestyle.

Population Relationships of individuals in a population

A population is a collection of individuals of the same species that have a common living space and type of relationship with each other. Individuals of the population differ among themselves in age and vitality (i.e.

Competition (biology)

life force), which can be determined genetically, phenetically, and more often - a combination of these factors.

A number of significant differences that need to be taken into account in population studies are populations of plants and animals. The main difference lies in the fact that animals with mobility can react more actively to the prevailing environmental conditions, avoiding unfavorable circumstances or dispersing over the territory to compensate for the decrease in the resource reserve per unit area. Mobility makes it easier for them to protect themselves from predators.

Due to the fact that populations are diverse, the interactions of the individuals that make up them also differ.

The main type of interaction between individuals in a population is competition, i.e. competition for the consumption of a resource that is in short supply. Competition can be symmetrical (competing individuals have the same effect on each other) or asymmetric (influence of individuals on each other varies in strength).

features of the competition of individuals in the population:

1. Competition reduces the growth rate of individuals, can slow down their development, reduce fertility and, as a result, reduce the contribution to the next generations. The number of descendants of a particular individual is the smaller, the tougher the conditions of competition and the less resources it got.

2. In most cases, individuals compete for resources: each individual receives that limited amount of resources that was not consumed by its competitors. Such competition is called exploitative. Less often there is a competition for physical space, when individuals “mechanically” prevent each other from obtaining a resource, for example, the protection of their territory by mobile animals. Such relationships are called interference.

3. Different individuals have different competitive ability. Despite the fact that all individuals of a population are potentially equivalent (their gene pool is constantly leveled due to hybridization), there is no equivalence of individuals in nature. As a result of asymmetric competition, a decrease in population density occurs: weak plants die, and weak animals migrate to habitats with a lower the level of competition.

In addition to competition, other forms of relations between individuals in populations are also possible - neutrality (if there are so many resources and so few individuals that they practically do not interfere with each other) and positive relationships.

Mutually beneficial (or beneficial for some individuals) relationships between animals are well known: parental care for offspring, the formation of large family groups, a herd lifestyle, collective defense from enemies, etc. "Caravans" of birds lining up in lines, wedges, ledges, etc. ., allow the wings of individual individuals, due to aerodynamic effects, to acquire greater lift (it is easier to fly in a team). There is an opinion that fish swimming in a flock also receive hydrodynamic advantages.

Much less known is the role of mutual aid in plants. Plants sown in a group develop better, since in this case they more easily form symbiosis with fungi and bacteria of the mycorrhiza and rhizosphere (the so-called “group effect”).

Phenomena of mutual assistance of plants are possible during the "collective defense" from phytophages, which exhibit excessively high activity and can seriously damage plants. In this case, after the start of active eating by phytophages, biochemical reactions occur in plants and the concentration of substances that reduce their palatability (cyanides, etc.) increases. Cases are described when individuals attacked by phytophages released signal substances into the atmosphere (“they eat me” signal), which caused an increase in the formation of cyanides in those individuals that were not yet damaged.

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Competition is the competition of organisms of the same trophic level (between plants, between phytophages, between predators, etc.) for the consumption of a resource that is available in limited quantities.

a special role is played by competition for the consumption of resources during critical periods of their scarcity (for example, between plants for water during a drought or predators for prey in an unfavorable year).

There are no fundamental differences between interspecific and intraspecific (intrapopulation) competition. There are both cases when intraspecific competition is more acute than interspecific, and vice versa. The intensity of competition within a population and between populations can vary under different conditions. If conditions are unfavorable for one of the species, then competition between its individuals may increase. In this case, it can be displaced (or, more often, displaced) by a species for which these conditions are more suitable.

However, in multi-species communities, pairs of "duelists" most often do not form, and competition is diffuse in nature: many species simultaneously compete for one or more environmental factors. "Duelists" can only be mass plant species that share the same resource (for example, trees - linden and oak, pine and spruce, etc.).

Plants can compete for light, for soil resources, and for pollinators. On soils rich in mineral nutrition resources and moisture, dense dense plant communities are formed, where the limiting factor for which plants compete is light.

When competing for pollinators, the species that is more attractive to the insect wins.

In animals, competition occurs for food resources, for example, herbivores compete for phytomass. At the same time, large ungulates can compete with insects like locusts or mouse-like rodents that can destroy most of the grass in years of mass reproduction. Predators compete for prey.

Since the amount of food depends not only on environmental conditions, but also on the area where the resource is reproduced, competition for food can develop into competition for the occupied space.

As in relations between individuals of the same population, competition between species (their populations) can be symmetrical or asymmetric. At the same time, the situation when environmental conditions are equally favorable for competing species is quite rare, and therefore relations of asymmetric competition arise more often than symmetrical ones.

With fluctuating resources, as is usual in nature (moisture or mineral nutrients for plants, primary biological production for different species of phytophages, prey population density for predators), different competing species alternately gain advantages. This also leads not to the competitive exclusion of the weaker, but to the coexistence of species that alternately find themselves in a more advantageous and less advantageous situation. At the same time, species can survive the deterioration of environmental conditions with a decrease in the level of metabolism or even transition to a dormant state.

The outcome of competition is also influenced by the fact that a population with more individuals and which, accordingly, will more actively reproduce “its own army” (the so-called mass effect) is more likely to win the competition.

23. The relationship of the plant phytophage and prey predator

RELATIONSHIP "PLANT-PHYTOPHAGE".

The relationship "phytophage - plant" is the first link in the food chain, in which the substance and energy accumulated by producers are transferred to consumers.

It is equally “unprofitable” for plants to be eaten to the end or not eaten at all. For this reason, in natural ecosystems, there is a tendency to form an ecological balance between plants and phytophages that eat them. For this plant:

- are protected from phytophages by thorns, form rosette forms with leaves pressed to the ground, inaccessible to grazing animals;

- protect themselves from complete grazing biochemically, producing toxic substances with increased consumption, which make them less attractive to phytophages (this is especially true for slow-growing patients). In many species, when they are eaten, the formation of "tasteless" substances is enhanced;

- emit odors that repel phytophages.

Protection from phytophages requires a significant expenditure of energy, and therefore tradeoff can be traced in the relationship “phytophage – plant”: the faster the plant grows (and, accordingly, the better the conditions for its growth), the better it is eaten, and vice versa, the slower the plant grows, the it is less attractive to phytophages.

At the same time, these means of protection do not ensure the complete safety of plants from phytophages, since this would entail a number of undesirable consequences for the plants themselves:

- uneaten steppe grass turns into rags - felt, which worsens the living conditions of plants. The appearance of abundant felt leads to the accumulation of snow, a delay in the start of plant development in spring and, as a result, to the destruction of the steppe ecosystem. Instead of steppe plants (feather grass, fescue), meadow species and shrubs develop abundantly. At the northern border of the steppe, after this meadow stage, the forest can generally be restored;

– in the savannah, a decrease in the consumption of tree shoots by branch-eating animals (antelopes, giraffes, etc.) leads to the fact that their crowns close. As a result, fires become more frequent and the trees do not have time to recover, the savannah is reborn into thickets of shrubs.\

In addition, with insufficient consumption of plants by phytophages, space is not freed up for the settlement of new generations of plants.

The “imperfection” of the “phytophage-plant” relationship leads to the fact that quite often there are short-term outbreaks of the density of phytophage populations and temporary suppression of plant populations, followed by a decrease in the density of phytophage populations.

RELATIONSHIPS "VICTIMS-PREDATOR".

Relationships "predator - prey" represent the links in the process of transfer of matter and energy from phytophages to zoophages or from predators of a lower order to predators of a higher order.

As with the “plant-phytophage” relationship, a situation in which all prey will be eaten by predators, which ultimately will lead to their death, is not observed in nature.

The ecological balance between predators and prey is maintained by special mechanisms that exclude the complete extermination of prey.

So victims can:

- to run away from a predator.

In this case, as a result of adaptation, the mobility of both victims and predators increases, which is especially characteristic of steppe animals, which have nowhere to hide from their pursuers (“Tom and Jerry principle”);

- acquire a protective color (“pretend” with leaves or twigs) or, on the contrary, bright (for example, red, warning a predator about a bitter taste. It is well known that the color of a hare changes at different times of the year, which allows it to camouflage in the foliage in summer, and in winter against a white background snow;

– spread in groups, which makes their search and fishing for a predator more energy-intensive;

- hide in shelters;

- switch to active defense measures (herbivores, horns, spiny fish), sometimes joint (musk oxen can take up “all-round defense” from wolves, etc.).

In turn, predators develop not only the ability to quickly pursue victims, but also the sense of smell, which allows them to determine the location of the victim by smell.

At the same time, they themselves do everything possible not to reveal their presence. This explains the cleanliness of small cats, which spend a lot of time on the toilet and burying excrement to eliminate the smell.

With intensive exploitation of phytophage populations, people often exclude predators from ecosystems (in the UK, for example, there are roe deer and deer, but no wolves; in artificial reservoirs where carp and other pond fish are bred, there are no pikes). In this case, the role of a predator is performed by the person himself, removing a part of the individuals of the phytophage population.

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Competition is a typical phenomenon for wildlife. It is caused by the struggle for resources. But if we talk about intraspecific competition, then it should be noted that this type of competition is most intense.

This is primarily due to the fact that individuals of the same species need some strictly defined resource, which may not be needed by individuals of another species. Therefore, often with this type of competition, there is a depletion of a resource or a certain type of resource.

For example, in a grass mixture consisting of peas and barley, the most fierce competition for soil nitrogen will be between barley plants. This is due to the fact that, due to the ability of peas to fix nitrogen from the air, the need for competition between pea sprouts for nitrogen in the soil is reduced.

Distinguish operational And interference competition.

The first is that all individuals simultaneously exploit resources, but each of them uses only what is left after the competitor. In the second case, one individual does not allow another to occupy the existing habitat and use its resource. Another form of competition is called fierce competition, and the second - rivalry. The first type of competition can lead to the death of the entire population. For example, in the green carrion fly, when the population of larvae on the food source is overcrowded, this type of competition can lead to the fact that at a certain age stage the entire population of offspring will die.

The rivalry is somewhat different. For example, if 150 pairs of birds claim for 100 hollows in some forest, it becomes obvious that 50 pairs will not be able to equip their nests in this area. Therefore, the only possible option for producing offspring can be the migration of these birds to another territory (i.e. emigration).

For a number of reasons, competing individuals of the same species are not equal in their ability to compete. Therefore, in nature, the strongest survive or the one who is more fortunate due to a combination of circumstances. So, the most common sprout, which has risen a little earlier than its fellow tribesmen, will further obscure undersized specimens.

Ignorance of the laws associated with intraspecific competition can lead to sad consequences. For example, in agricultural production, a significant excess of seed sowing rates per unit area can lead to a complete loss of the crop. Exhausted by competition, numerous plants will simply not be able not only to produce a crop, but even to survive to reproductive age.

Competition is directly related to such a concept as an ecological niche, which is not only certain environmental conditions to which an organism is adapted, but also a way of life and a way of obtaining food. Often this term is applied mainly to interspecific competition, but in fact, the ecological niche is characteristic even for each individual organism of the same species.

Another interesting factor in intraspecific competition is the body size of organisms. So, the growth of fish does not stop even after reaching puberty, and is determined by food reserves. The American ecologist R. Whittaker gives an example of this. There are two identical ponds. In the first pond, 100 fry are released, and in the second - 50. As a result, after an equal period of time, the size of the fish in the first pond can be half that in the second. However, the weight of fish in both the first and second ponds may be approximately the same.

In addition to the monotonous depletion of resources, intraspecific competition can also lead to intoxication of the entire population. This is because the excretory products of organisms of the same species are, in fact, poison for them. For example, in a plant community, the root secretions of some plant species can be nutrients for other plant species. Therefore, in the wild, it is not often possible to find communities represented by a single species.

Even grandfather Darwin in his evolutionary theory noted that the severity of the struggle for existence is most pronounced among representatives of one species. And although in the field of recent achievements in genetics and a number of other biological sciences, an increasing number of comments and claims arise to the theory of Charles Darwin, nevertheless, so far no one has come up with anything more significant in biology.

According to the Ukrainian ecologist V. Kucheryavy: “Intraspecific competition has many negative consequences. It not only impoverishes resources and leads to environmental intoxication, but also promotes self-aggression and cannibalism, social and reproductive failure.”

The above quote willy-nilly evokes associations with human society. There was a time when analogies of the laws of nature with relationships within human society led a number of thinkers to create such a doctrine as social Darwinism, which, according to the ecophilosopher M. Bookchin, “connected all the wild features of civilization with our genetic constitution.” According to this doctrine, property inequality in society is explained as interspecific competition between individuals of one species of one population.

And geopolitical inequality between states is explained as intraspecific competition between populations of the same species.

At first glance, everything is correct. However, if we take social Darwinism seriously, then it turns out that a reasonable person, in fact, is not such, but is a typical biological species. It is obvious that this is not the case. But the main flaw of this teaching is that it does not try to change something for the better, but tries not so much to explain as to justify the existing state of affairs. Social Darwinism does not reflect the most important thing - the future perspective. Indeed, in the current environmental realities, it becomes clear that both intraspecific and interspecific human competition depletes the resources of the biosphere so much that it undermines the biological diversity of the entire global ecosystem, and therefore threatens the human species itself.

In modern biological science, scientists are increasingly paying attention not to competition, but to mutual assistance and cooperation. But more on that in one of the next posts. Briefly, we can say the following. Man is a social being, therefore a number of biological laws are leveled due to artificial social institutions and established norms of behavior. At the same time, one should not underestimate the biological laws in the life of the human species. It can be said that many social mechanisms are only a means that simply delays the reaction of biological laws. And as soon as this mechanism is destroyed due to spontaneous, competitive or resource overload, then the biological laws of survival manifest themselves in their entirety.

Competition occurs between organisms that have similar or identical needs and use the same resources. So one of them consumes the resources of the other, which impairs its growth, development and reproduction. Such a resource is usually limited. It can be food, territory, light, and the like. There are two types of competition: intraspecific, when individuals of different species, genera become competitors, and interspecific.

Intraspecific competition occurs when the needs of a certain type of organisms exceed the reserves of the necessary resource and some individuals of the species do not receive it. Competition increases with the increase in the population of the species. There are two forms: a) operational, when individuals that compete do not interact directly with each other, but each receives that part of the resource that has remained to it from others; b) interference, when one individual actively prevents another from using the resource (protection of “their” territory by animals, colonization of the biotope by plants, etc.). Intraspecific competition affects fertility, mortality, growth and abundance (density). The combination of these effects of competition affects the growth of biomass, and in some cases leads to morphological changes, in particular, thinning of the stem and trunk. The struggle for light and moisture changes the habitus of the crown, causes the lateral branches to dry out and fall off, the formation of the apical crown can be better seen on the example of pine, spruce and other coniferous and broad-leaved species.

Interspecific competition takes on acute forms between species that have similar life requirements and occupy the same ecological niche in the biogeocenosis. Thus, the vital interests of these species intersect, and they try to defeat a competitor. Competition causes oppression or complete exclusion from the ecological niche of one species and its replacement with another, more adapted to environmental conditions. Competition plays an important role in the process of speciation as one of the most effective factors of natural selection.

Interspecific, as well as intraspecific competition are divided into operational and interference, or direct and indirect. Both forms are inherent in both plants and animals. An example of a direct impact on competitors is the shading by one species of another. Some plants release toxic substances into the soil, and this inhibits the growth of other species. For example, chestnut leaves, when decomposed, release toxic compounds into the soil, inhibiting the growth of seedlings of other species, and several species of sage (Salvia) produce volatile compounds that adversely affect other plants. Such a toxic effect of some plants on others is called allelopathy. Indirect competition is not as tangible as direct competition, and its consequences appear after long-term exposure in the form of differentiated survival and reproduction.

The relationship between different organisms, in which they begin to compete with each other, is competition. The subject area does not matter. In biological relationships, this is a type of biotic relationship. Organisms compete for consumption of limited resources. There are other types of competition, such as economic competition.

Rivalry in nature

Intraspecific competition is inherent in the rivalry between individuals of the same species for the same resources. Thus, intraspecific competition influences the self-regulation of a population. Examples of such rivalry: the nesting place of birds of the same species, the rivalry between male deer and other mammals for the right to a female during the breeding season.

Interspecific competition is also characterized by competition for resources. But it happens between different species of individuals. Such competition (examples: hunting of a fox and a wolf for a hare) is very numerous. Predators compete for food. They rarely come into direct confrontation. As a rule, the failure of one turns into a success for another.

Intensity of competition

Organisms at the trophic level also have their own competition. Examples: competition for the consumption of a limited resource between plants, phytophages, predators, etc. This is especially noticeable at critical moments when plants fight for water during a drought, when predators have an unfavorable year and they fight for prey.

Under different conditions, the intensity of competition between and within populations may vary. But there are no fundamental differences between the types of rivalry. It happens that intraspecific competition is more acute than interspecific. It happens the other way around. If conditions are unfavorable for one species of individuals, then they may be suitable for another. In this case, one species is replaced by another.

But in communities where there are many species, competition of a diffuse nature most often takes place (examples: many species simultaneously compete for a certain environmental factor or for several factors at once). Duels only occur among mass plant species sharing the same resources. For example: linden and oak, pine and spruce and other types of trees.

Other examples of competition

Is the struggle between plants for light, for soil resources, for pollinators? Certainly yes. Plant communities are formed on soils rich in minerals and moisture. They are thick and tight. Therefore, the light for them is limited. They have to compete for it. Insect pollinators also choose a more attractive plant.

The animal world also has its own examples of competition. Is the struggle of herbivores for phytomass competition? Of course yes. Surprisingly, insects like locusts, mouse-like rodents, which are capable of destroying most of the grass stand during mass reproduction, can be rivals for large-hoofed insects. Predators compete for prey, and competition for food develops into a struggle for space. This is because the availability of food depends not only on the ecology, but also on the area.

rivalry between species

As with the relationship of individuals of the same population, interspecific competition (examples were given above) can be asymmetric and symmetrical. At the same time, asymmetric competition is more common. This is due to the fact that the same environmental conditions, favorable for rival species, are extremely rare.

There are usually fluctuating resources in nature. Therefore, different competing species alternately receive advantages. This leads to the development of the coexistence of species and their improvement. They alternately fall into more or less favorable conditions. In addition, the outcome of competition is influenced by the mass character of the population. The larger it is, the higher the chances of winning.

tough fight

If you study thoroughly all the scientific writings that describe competition, you may get the impression that in systems without immigration and emigration, or where they are reduced, there is a very fierce struggle. Such an example of the competition of organisms are laboratory cultures, communities on islands, or other natural situations with difficult to overcome obstacles to leaving the system or entering it. If we are talking about ordinary open natural systems, then the probability of coexistence is much higher.

How does intraspecific competition manifest itself? Examples of such rivalry

An example of competition within one species of individuals is a population of grasshoppers of the same species. In search of food, they waste energy, exposing themselves to the danger of becoming food for other individuals. When the density of their population increases, so does the cost of energy for life support. Then intraspecific competition increases. Energy costs rise, the rate of food consumption decreases, the chances of survival are minimized.

In plants, the situation is similar. If there is only one seedling, it has a better chance of surviving to reproductive maturity than one that grows in dense growth. This does not mean that he will die, but, most likely, he will be small, undeveloped. This will affect the offspring. Therefore, we can conclude that an increase in population density reduces the contribution of an individual to offspring.

Common features

Summing up, we can say that intraspecific competition has the following common features:

• The rate of consumption of resources by individual individuals decreases.
• There is limited resources, which is why there is competition.
• Competing individuals of the same species are unequal.
• There is a direct dependence that affects an individual on the number of competitive counterparts.
• The result of competition is a decrease in the contribution to offspring.

Aggressiveness

Competitive struggle within one species can be expressed aggressively (actively). It can be psychological, physical, chemical. It happens that students are asked the question: “What is aggressive intraspecific competition? Give examples of active competition. Then you can talk about males competing for a female. They behave actively, demonstrate the superiority of their appearance, try to outshine their opponent. It happens that with the help of smell they keep a competitor at a distance. It happens that they enter into battle with the enemy.

Competition in the economy

In economics, competition is considered as part of the market mechanism. It balances supply and demand. This is a classic look. There are two more approaches to the concept of competition:

• it is competition in the market;
• criterion that determines the type of industry market.

There are different degrees of perfection of competition in the market. Depending on this, different types of markets are distinguished. Each type has its own specific behavior of economic entities. With this approach, competition is understood not as rivalry, but as the degree of dependence of general conditions on the market on the behavior of its participants, existing separately from each other, but somehow having certain dependencies.

Competition is behavioral, structural and functional. In behavioral competition, there is a struggle between competitors for the buyer's money by satisfying his needs. When structural competition takes place, there is an analysis of the market structure in order to determine the degree of freedom of buyers and sellers in the market, as well as ways to exit it. With functional competition, there is a rivalry between old and innovative approaches, methods and technologies.

Research methods

In modern economic science, two methods of studying competition are used: institutional and neoliberal. Institutional theory takes into account economic, social, political, organizational, socio-psychological factors and features of a particular system.

Competition is a kind of motivating motive, a stimulus for development. It is possible to achieve high results in the economic sphere only if there is competition. It is possible to cite quite a lot of confirming facts of this theory from world history.

Perfect Market

In today's market conditions, perfect and imperfect competition are distinguished. Freedom of choice is the key concept that perfect competition implies. You rarely see examples of such a market. In 1980, US agricultural prices plummeted. At first, farmers blamed government agencies. But when they began to get on the huge commodity exchange in Chicago, they were convinced that the offer was huge and no one could artificially lower prices. There was fair competition. The market brought together a very large number of participants from both sides. Prices were dictated by the market. Only the balance of buyers and sellers affected the final cost of goods. Farmers stopped blaming the state and took steps to overcome the crisis.

Perfect competition is the absence of limitation in sellers and buyers. It is the inability to control prices. With such competition, an entrepreneur can easily enter the industry. Buyers and sellers have equal access to market information.

An example of perfect competition can be seen by examining the first stages of the development of an industrial society. Then the market was dominated by goods of a standard type and quality. The buyer could easily evaluate everything. Later, these properties became characteristic only for the commodity and agricultural markets.

• prices for goods for all buyers and sellers are the same;
• access to information about the market is free for all its participants;
• the product is identical, and the number of market participants on both sides is huge;
• any producer can enter freely into any sphere of production;
• no seller can influence pricing individually.

Imperfect Market

Imperfect competition is a market where at least one sign of perfect competition is not observed. This type of competition involves the presence of two or more sellers who have the opportunity to influence pricing in one way or another. They are the main competitors. In an imperfect market, either sellers or buyers take into account their ability to influence the price.

There are two types of imperfect competition:

• monopolistic competition (examples are numerous, for example, the mobile communications market);
• oligopoly;
• monopoly.

Monopolistic competition is the leading form in modern business. With it, a lot of subjects offer one special product, information, service or other nature. They are both monopolists and competitors, while having real leverage to control the price of their particular products.

Oligopoly refers to an industry market. Such an example of economic competition, where there is an oligopoly, can be found in the field of oil and gas production and processing. This competition is characterized by the presence of several largest companies that control a significant part of the production and marketing of products. At the same time, these companies are in serious competition with each other. Each of them has an independent market policy, which nevertheless depends on competitors. They have to reckon with each other. In such a market, goods can be both differentiated and standard. There are significant barriers to entry in this industry.

Monopoly is also a type of industry market. The monopolist is one of a kind. It cannot be replaced, even approximately. It controls the price and volume of output. As a rule, he receives superprofits. A monopoly can be created artificially: exclusive rights, patents, copyrights, ownership of the most important raw materials. It is almost impossible to enter such an industry. The barriers are too high.

The concept of competition is increasingly covered in the field of economics, but its origins still come from biology. What does this concept mean? What is the role of competition in wildlife? Read about the types and mechanisms of competition later in the article.

Various effects on organisms

No living organism exists in isolation. It is surrounded by many factors of animate and inanimate nature. Therefore, in one way or another, it constantly interacts with the environment, other organisms. First of all, the biosphere affects a living being, its components include the lithosphere, hydrosphere, and also the atmosphere. The vital activity of plants and animals is directly related to the amount of sunlight, access to water resources, etc.

Organisms also experience significant influence from interaction with each other. Such influences are called biotic factors, which manifest themselves as the impact of living organisms on plants, which, in turn, affects the habitat. In biology, they are divided into trophic (according to nutritional relations among organisms), topical (relative to changes in the environment), factory (depending on the place of residence), phoric (the possibility or impossibility of transporting one organism to another) factors.

Interaction of living organisms

Carrying out their vital activity, living organisms certainly affect the "personal space" of other organisms. This can occur both between representatives of the same species, and different ones. Depending on whether the interaction harms organisms or not, there are neutral, positive and negative types of relationships.

A relationship in which both organisms get nothing is called neutralism. Positive interaction is mutualism - mutually beneficial cohabitation of individuals. Allelopathy can be called a completely negative relationship, when cohabitation harms both participants. This also includes intraspecific and interspecific competition.

Important factors for the normal life of animals, plants, microorganisms is the resource of the environment and space. With their shortage between living organisms, competition appears. This is a kind of antibiosis - an antagonistic relationship where different individuals are forced to fight for their existence.

Rivalry in wildlife often occurs when individuals have similar needs. If the struggle occurs among individuals of the same species, this is intraspecific competition, if to different - interspecific.

Live organisms can compete openly, directly interfering with the opponent's life. For example, when the roots of some plants oppress others, or some animals drive others away from a hot spot. Competition can also be indirect. It manifests itself when the opponent more actively destroys the necessary resource.

intraspecific competition

Examples are quite common. This type of competition is observed between individuals of one or more populations. The main reason for this is the same structure of organisms, and hence the same needs for environmental factors and food.

Intraspecific competition is more severe than interspecific. The manifestation of such a struggle can be observed in the delimitation of the territory between individuals. So, bears leave claw marks on tree trunks, warning of their presence. To separate the space, smell is often used, a loud signal cry. Sometimes individuals simply attack each other.

If the competition takes place for resources, then sometimes it is asymmetrical. In this case, one side suffers more than the other. As a result of intraspecific competition, eventually one of the populations may disappear or change.

Why is there competition?

One of the most important tasks of living organisms is to survive, while passing on the best genetic material to the offspring. In ideal conditions, an ecological vacuum, there are no obstacles for this, and therefore there is no rivalry.

Intraspecific competition occurs under adverse environmental conditions, when organisms are forced to fight for light, water or food. Severe conditions can lead to a change in the life cycle of the species, accelerate its development. However, this is not required. Sometimes rivalry occurs when individuals compete for dominance in a herd, pack, or pride. This behavior is observed in animals that have a developed social hierarchy.

An important role is played by Excessive growth of the population of one species over time leads to a shortage of the resource, which can lead to the extinction of the species. To avoid this, some species, such as rodents, even develop shock sickness. The ability of animals to reproduce sharply decreases, but the susceptibility to various diseases increases.

Role and mechanisms of competition

Competition is the most important tool of nature. First of all, it is designed to regulate the number of individuals. Each species has its own allowable density values, and when there are too many individuals within one population, control mechanisms are activated. To fulfill this role, nature uses various methods: an increase in mortality, the division of territory.

In conditions of high numbers and limited space, some individuals may leave their habitual habitat and develop another one. So two different ones stand out from one population. This ensures the wide distribution of the species and high survival. In certain species, this process is temporary, for example in migratory birds.

As a result of intraspecific competition, the more resistant and viable individuals ultimately survive. Their physiological qualities are transmitted genetically, which means they contribute to the improvement of the species.

Examples of intraspecific and interspecific competition

It is not always easy to distinguish between two main types of competition. It is better to understand this visually. can serve as a "victory" of the gray rat over the black one. They belong to the same genus, but are different species. The gray rat is more aggressive and predominate in size, so it could easily force the black rat out of human homes. But black was a frequent guest on the ships of navigators.

As a model of intraspecific competition, one can mention cannibalism, which is observed in approximately 1300 animal species. The female praying mantis will eat the male immediately after mating. The same behavior is observed in pak-karakurts. Scorpions and salamanders eat part of their offspring. In many beetles, the larvae eat their fellows.

The type of internal competition is territoriality. It is seen in fish, penguins, and most other birds. During the breeding season, they do not allow representatives of their species into their own territory, which is carefully guarded.

Plant competition

Plants, although they cannot openly attack an opponent and scare him away, also have their own methods of rivalry. They fight mainly for light, water and free space. In severe conditions of existence, intraspecific competition of plants manifests itself in the form of self-thinning.

This process begins with the spread of seeds and the capture of territory by the plant. Sprouted seedlings cannot develop in the same way, some grow more actively, others more slowly. Tall trees with spreading crowns shade other trees, taking all the solar energy for themselves, and their powerful roots block the path to nutrients. So small and weak plants dry up and die.

Competition is displayed on the appearance of plants. Representatives of one species can vary significantly, depending on the degree of their isolation from other individuals. You can observe this phenomenon in oak. Separately growing, it has a wide, spreading crown. The lower branches are strong and well developed, no different from the upper ones. In the forest, among other trees, the lower branches cannot receive enough light and die off. Oak takes on a narrow, elongated crown shape instead of a spherical one.

Conclusion

Competition is one type of relationship. It occurs between all living organisms without exception. The main objective of competition is to regulate the density of individuals, as well as increase their ability to survive. Often the competition is due to the struggle for food, water, light or territory. It can result from a severe shortage of one of these resources.

Rivalry tends to occur between species that have similar needs. The more similarities in living organisms, the stronger and more aggressive the fight. Individuals of the same or different species can compete for a resource. Intraspecific competition often occurs to establish a dominant individual and also to ensure that the population does not grow excessively.

Types of interaction between two views

The essence of interspecific competition lies in the fact that individuals of one species have reduced fertility, survival or growth rate as a result of resource use or interference from individuals of another species. However, behind this simple formulation lies a large number of very diverse nuances. The influence of interspecific competition on the population dynamics of competing species is many-sided. Dynamics, in turn, can influence the distribution of species and their evolution.

All these types of interactions are shown in Table 1.

Table 1 Analysis of interactions between populations of two species

Type of interactions		General nature of interaction
1. Neutralism			Neither population affects the other
2. Competition			Direct mutual suppression direct both types
3. Competition			Indirect suppression in case of shortage of a shared resource
4. Amensalism			Population 2 suppresses population 1, but is itself not adversely affected.
6 Predation			Predators are usually larger than prey
7. Commensalism			Population 1, the commensal benefits from overeating; population 2 this merger is indifferent
8. Protocooperation			The interaction is favorable for both species, but not necessarily
9. Mutualism			The interaction is favorable for both species and is mandatory

• 1. 0 means no significant interactions; + means improved growth, survival, and other benefits to the population (a positive term is added to the growth equation); - means a slowdown in growth and deterioration in other characteristics (a negative term is added to the growth equation).
• 2. Types 2-4 can be considered "negative relationships", types 7-9 - "positive relationships", and types 5 and 6 can be attributed to both of these groups.

Three principles based on these categories should be emphasized:

• · Negative interactions appear at the initial stages of community development or in disturbed natural conditions, where high mortality is neutralized by r-selection.
• In the process of evolution and development of ecosystems, there is a tendency to reduce the role of negative interactions due to positive ones that increase the survival of interacting species
• • Newly formed or new associations are more likely to have strong negative interactions than old associations.

Effect on growth rate or mortality

One population often affects the growth rate or mortality of another. Thus, members of one population may eat members of another population, compete with them for food, release harmful substances, or interact with them in other ways. In the same way, populations can be useful to each other, and the benefit in some cases is mutual, and in others - one-sided. As shown in Table 1, interactions of this kind fall into several categories.

To clarify the action of various factors in complex natural situations, as well as to more accurately define concepts and make reasoning clearer, it is useful to use "models" in the form of equations. If the growth of one population can be described by an equation, then the effect of another population can be expressed by a term that changes the growth of the first population. Depending on the type of interaction, different terms can be substituted into the equation. For example, in the presence of competition, the growth rate of each population is equal to the rate of unlimited growth minus the influence of its own abundance (which increases with the growth of the population) and minus the value characterizing the negative influence of another species, N2 (which also increases as the numbers of both species N1 and N2 increase). ), or

growth rate;

Unlimited growth;

Influence of own numbers;

Negative influence of another kind.

When the species of two interacting populations have a beneficial rather than a damaging effect on each other, a positive term is introduced into the equation. In such cases, both populations grow and prosper, reaching equilibrium levels, which is beneficial for both species. If for the growth and survival of each of the populations their mutual influence on each other is necessary, then such relationships are called mutualism. If, on the other hand, these favorable influences only cause an increase in the size of the population or the rate of its growth, but are not necessary for its growth and survival, then such an interaction corresponds to cooperation or proto-cooperation. (Since such cooperation is not the result of conscious or "intelligent" activity, it is preferable to use the latter term.) Both mutualism and protocooperation lead to a similar result: population growth in the absence of the other is either slowed down or equal to zero. Upon reaching equilibrium, both populations continue to coexist, usually maintaining a certain ratio.

Competition and coexistence of species

In the broadest sense, competition is the interaction of two organisms seeking to obtain the same resource. Interspecific competition is any interaction between populations of two or more species that adversely affects their growth and survival. As shown in Table 1, it can appear in two forms. The tendency towards ecological separation observed when closely related or otherwise similar species compete is known as the principle of competitive exclusion. At the same time, competition contributes to the emergence of many adaptations in the process of selection, which leads to an increase in the diversity of species that coexist in a given space or community.

Competitive interactions may involve space, food or nutrients, light, unused substances, dependence on predators, exposure to disease, etc., and many other types of interactions. The results of the competition are of great interest; they have been repeatedly investigated as one of the mechanisms of natural selection.

Interspecific competition, no matter what it is based on, can either lead to an equilibrium between two species, or, with more severe competition, to the replacement of a population of one species by a population of another, or to one species crowding out another elsewhere. or force him to switch to the use of other foods. It has been repeatedly noted that closely related organisms that lead a similar way of life and have a similar morphology do not live in the same places. If they live in the same place, they often use different resources or are active at different times.

The explanation for the ecological separation of closely related (or otherwise similar) species has come to be known as the Gause principle, after the Russian biologist who, in 1932, first confirmed its existence experimentally or as a principle of competitive exclusion (Harden, 1940).

To understand the causes of competition, it is necessary to consider not only the characteristics of populations and the conditions that determine competitive exclusion, but also situations in which similar species coexist, since in open natural systems a large number of species actually use common resources. The table shows a situation that could be called the Tribolium (hrushchaki) - Trifolium (trefoil) model; this model clearly demonstrates the competitive exclusion in a pair of beetle species (Tribolium) and the coexistence of two clover species (Trifolium).

One of the most rigorous and lengthy experimental studies of interspecific competition was conducted in the laboratory of Dr. Thomas Park at the University of Chicago. Park and his students and staff have worked with mealworms, in particular species of the genus Tribolium. These small beetles can complete their entire life cycle in a very simple and homogeneous environment - in a jar of flour or wheat bran. In this case, the environment serves both as food and as a habitat for larvae and adults. By regularly adding fresh media, the beetle population can be maintained for a long time. From the point of view of ideas about the energy flow, such an experimental system can be described as a stabilized heterotrophic ecosystem in which the import of food energy is balanced by the cost of respiration.

Table 2. Case of competitive exclusion in mealworm (Tribolium) populations. (According to Park, 1954).

1. Each of the 6 variants of experiments was carried out in 20 - 30 repetitions. In a pure culture, each species survives under any combination of conditions, but when two species are cultivated together, only one survives. The percentage expresses the relative number of repetitions in which only one species was preserved, while the other disappears.

Using the data obtained in model experiments on Tribolium, it is easy to create conditions in which species would not exclude each other, but coexist. If crops are placed alternately between hot and humid and dry and cold conditions (to simulate seasonal changes in the weather), the advantage of one species over the other will not be long enough to destroy the other. If the culture system were "open" and individuals of the dominant species were forced to emigrate (or removed, as a predator does) quickly enough, then competition would be so weak that both species could coexist. Many other conditions could also favor existence.

Interesting experiments on competition in plants were conducted by J. L. Harper and his colleagues at the University College of North Wales. Due to differences in the nature of growth, two types of clover can coexist in the same environment (under the same conditions of illumination, temperature, on the same soil, etc.). Of these two species, Trifolium repens grows faster and reaches its maximum leafiness sooner. However, T. fragiferum has longer petioles and higher set leaves, so it can move to the topstory earlier than the fast growing species (especially after the growth rate of T. repens has waned) and thus avoid shading. In mixed grass stands, due to these features, each species inhibits the development of the other, but both of them are able to complete the life cycle and produce seeds, although the density of each species is reduced (however, the total density in mixed grass stands of the two species was approximately equal to the density in pure grass stands) . In this case, both species, despite strong competition for light, can coexist, and this coexistence is due to morphological features and differences in the time of maximum growth. Harper (Naggreg, 1961) concluded that two plant species can coexist for a long time if their populations are independently regulated by one or more of the following mechanisms: 1) differences in nutritional requirements (eg, legumes and non-legumes); 2) differences in the causes of mortality (for example, different susceptibility to grazing); 3) sensitivity to different toxins; and 4) sensitivity to the same regulatory factor (light, water, etc.) at different times (as in the case of the clover example just described).

In examining the literature on competition, the general impression is that in systems where immigration and emigration are absent or reduced, competition is fiercer and competitive exclusion is more likely. Such systems include laboratory cultures, islands, or other natural situations with insurmountable barriers to entry and exit. In ordinary natural open systems, the probability of coexistence is higher.

An example of competition with direct suppression is described by Crombie (1947). He found that co-cultivation in flour of Tribolium and Oryzaephilus (another genus of mealworms) resulted in the destruction of Oryzaephilus, as Tribolium more actively exterminated immature stages of Oryzaephilus.

However, if glass tubes are placed in the flour, in which immature individuals of the smaller Oryzaephilus can hide, then both populations will survive. Thus, if there are shelters in the environment that allow one to hide from direct influence (in this case, predation), then competition is reduced so much that both species are preserved.

But enough laboratory examples. It is clear that crowding in laboratory experiments can be quite significant, leading to excessive competition. In field studies, interspecific competition has been studied in detail in plants; the results of these studies led to the conclusion (at present, this conclusion is generally accepted) that competition is an important factor causing the change of species. Keever (Keever, 1955) described the case when the fallow of the first year was almost entirely occupied by a pure herbage of a tall weed, later it was gradually replaced from here by another species, previously not known in these places. These two species, although they belong to different genera, have very similar life cycles (the time of flowering and seed maturation) and life forms, fell into conditions of intense competition. Careful follow-up studies of these fallow fields showed that the newcomer did not crowd out the previously growing species; it turned out that both species coexist, but their numerical ratio depends on the soil, time and degree of disturbance.

The following example concerns two species of terrestrial salamanders, Plethodon glutinosus and P. jordani, found in the southern Appalachian Mountains in the United States.

P. jordani is usually found at higher altitudes than P. glutinosus, but in some areas their ranges overlap. Hairston (1980) experimented on two sites, one in the Great Smoky Mountains, where overlap was observed only over a small range of altitudes, and the other in the Balsam Mountains, where the species coexisted over a much wider area. Both sites were inhabited by populations of both species and, in general, the salamander fauna was similar; the populations were at the same altitude and were subjected to the same influences. At each site

Hairston set up seven experimental plots: P. jordani specimens were removed from two of them, P. glutinosus specimens were removed from the other two, and the remaining three served as controls. This work was started in 1974, and over the next 5 years, the number of individuals of each species was counted 6 times a year at all sites; All individuals were divided into three groups: one-year-olds, two-year-olds, and all the rest.

On the control plots, as expected, P. jordani was much more numerous of the two species under consideration; and the sites from which it was removed showed a statistically significant increase in the abundance of P. glutinosus. The sites from which P. glutinosus was removed did not show a corresponding significant increase in P. jordani abundance. However, a statistically significant increase in the proportion of P. jordani among yearlings and two year olds was observed in both plots. Apparently, this was due to increased fecundity and (or) increased survival of juveniles; both of these factors are the main reasons that determine the rate of reproduction.

An important point is that individuals of both species initially experienced adverse effects from another species; after the removal of one of their species, the remaining one showed a significant increase in the number and (or) fertility and (or) survival. It follows that in the control plots and in other places of joint habitat, these species usually competed with each other, but still coexisted.

As another example, I will cite an experiment performed by one of the most famous "founding fathers" of plant ecology, A.G. Tansley, who studied competition between two species of bedstraw (Tansley, 1917). Galium hercinicum is a species that grows in the UK on acidic soils, while Galium pumilum is limited to more alkaline soils.

Growing the species separately, Tansley found that each of them grew well in both the acidic soil from the Galium hercinicum locality and the alkaline soil from the Galium pumilum locality. However, only Galium hercinicum grew successfully in acidic soil, and Galium pumilum in alkaline soil. Apparently, these results indicate competition between species when they are grown together. In the competitive struggle, one species wins, while the other loses so much that it is forced out of the biotype. The outcome of competition depends on the conditions under which it occurs.