The type of behavior during intraspecific competition is called. Competitive relations
For intraspecific competition have their own characteristics. The reason for its occurrence is a typical situation when the resource for which individuals of a population are fighting is quantitatively limited. Fierce competition arises (for territory, food resources, etc.), which is observed at high population densities.
Another form of intraspecific competition is rivalry, when one individual prevents another from occupying an existing territory and using its resources. In this case, a form of ideal or uncompromising competition is possible, which is resolved by emigration to other territories.
The severity of competition and its impact on the population depends on density, which determines the frequency and intensity of contacts between competitors.
Intraspecific competition not only depletes resources and thereby leads to increased mortality and stunted growth of individuals, it encourages self-aggression, cannibalism, and reduces the realization of the potential contribution of an individual to the next generation and the development of the population.
Intraspecific competition between individuals of a population in plants can be characterized as a struggle for light, heat, moisture, and area of mineral nutrition. In this competition, the more developed organisms that are nearby, displace the weak ones completely or strongly suppress their development and lead to gradual death. That is why, in agrophytocenoses 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 populations self-regeneration of plants occurs - 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 plantings. The liquefaction of the tree stand occurs the faster, the more light-loving the species and the better the environmental conditions. The latter is associated with an increase in the growth rate in good conditions and, accordingly, an increase in its needs, which makes competition 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 greatest stability of the population, reduces the severity of competition.
In animals different types Also, in the process of evolution, appropriate adaptive adaptations to life in an environment sparsely saturated or densely populated with individuals of the population were developed.
Appropriate biological properties and life strategy, enable organisms to reproduce and survive in conditions of a “competitive vacuum” (absence or little competition). In the first case, small animals can reproduce, their descendants will survive, although the population density will be high.
In the second case, large animals and their relatively similar descendants can survive the competition for space and food. Therefore, the main energy of organisms is aimed at competition, at increasing their survival, at producing competitive descendants.
These trends and strategy various types reflected in two opposing types of natural selection: r - and k - selection, which are discussed in Chapter 2.
Intraspecific competition between plant individuals of the same population can be calculated using Yoda's equation. According to this equation average value area per individual (a) is inversely proportional to population density (d).
Competition(from Late Latin concurentia - to collide), a type of relationship between organisms of the same or different species competing for the same things environmental resources(sexual partners, food, territory, shelters, etc.) with a lack of the latter. Intraspecific competition is considered the most important form of struggle for existence, since potentially the most intense competitive relationships arise between more similar individuals. For example, in mammals competition between males for the possession of a female is clearly expressed during the breeding season. During the rut, males of many species ( deer, rams, bears) organize fierce tournament battles.
Competition for territory, shelter and food is most fully expressed in territorial species with a solitary lifestyle (some mouse-like rodents, mole rats, carnivores mammals). However, in nature there are mechanisms (ecological, 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, without bringing the contact to physical interaction.
Interspecific competition is more often observed between individuals of ecologically similar species that use the same habitats and food resources. Such functionally similar groups of species, which interact strongly with each other and weakly with other species of the biocenosis, are often identified in guilds (the term was proposed by R. B. Root in 1967). The concept of guilds is closely related to the ecological niche model.
Competition can be passive (indirect), through the consumption of environmental resources needed by both species, and active (direct), accompanied by the suppression of one species by the other. The first option is often called exploitative competition, and the second - interference competition. 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 energetically unprofitable for both competitors, therefore, in nature, various mechanisms are implemented that reduce the intensity of interspecific competitive relations, based, in particular, on the division of resources and the formation of different ecological niches. The results of intraspecific and interspecific competition are usually different (see also Speciation). The first leads to the culling of the least competitive (least fit) individuals and, under conditions of a constant environment, to a narrowing of the reaction rate of the species, specialization (stabilizing selection; see. Natural selection), and in conditions of a directionally changing environment - to a shift in the reaction norm 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 conditions of a directionally changing environment - to a shift in the reaction norm 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 that reflect the connections between them. Each animal species performs a specific role in the community in relation to other living organisms.
Most obvious form relationships between animals is predation. In natural communities, there are herbivores that eat vegetation, and there are carnivores that catch and eat other animals. In relationships, herbivores act victimsami, and carnivores - predatorami. Moreover, each victim has its own predators, and each predator has its own “set” of victims.
INTRASPECIFIC COMPETITION
For example, lions hunt zebras and antelopes, but not elephants or mice. Insectivorous birds only catch 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 better, while others have a structure that allows them to better run away or hide. As a result, predators catch and eat only the weakest, sickest and least adapted animals.
Predators don't always eat herbivores. There are second- and third-order predators that eat other predators. This often occurs among aquatic life. So some species of fish feed on plankton, others on these fish, and a number of aquatic mammals and birds eat the latter.
Competition- a common form of relationships in natural communities. Typically, competition is most intense between animals of the same species living in the same territory. They have the same food, the same habitats. Competition between animals of different species is not so intense, 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 different image life.
Population Relationships between 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 from each other in age and vitality (i.e.
Competition (biology)
vital 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 exist between plant and animal populations. The main difference is that animals with mobility can react more actively to developing environmental conditions, avoiding unfavorable circumstances or dispersing across the territory to compensate for the decrease in the supply of resources 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 within 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 influence on each other) or asymmetrical (individuals have different influences on each other).
Features of competition between individuals in a population:
1. Competition reduces the growth rate of individuals, can slow down their development, reduce fertility and, as a result, reduce the contribution to subsequent generations. The number of descendants of a particular individual is smaller, the tougher the competition conditions and the fewer resources it gets.
2. In most cases, individuals compete for resources: each individual receives that limited amount of resources that were not consumed by its competitors. This type of competition is called exploitative competition. Less often, competition for physical space occurs when individuals “mechanically” prevent each other from obtaining a resource, for example, when mobile animals protect their territory. Such relationships are called interference.
3. Different individuals have different competitive ability. Despite the fact that all individuals of the population are potentially equivalent (their gene pool is constantly leveled due to hybridization), in nature, equivalence of individuals is not observed. As a result of asymmetric competition, the population density decreases: weak plants die, and weak animals migrate to habitats with lower level of competition.
In addition to competition, other forms of relationships between individuals in populations are 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: the care of parents for their offspring, the formation of large family groups, herd lifestyle, collective defense from enemies, etc. “Caravans” of birds, lining up in ranks, wedges, ledges, etc., allow the wings of individual individuals, due to aerodynamic effects, to gain greater lift(it’s easier to fly in a team). It is believed that fish swimming in schools also gain hydrodynamic advantages.
The role of mutual aid in plants is much less known. Plants sown in a group develop better, since in this case they more easily form symbiosis with fungi and bacteria of mycorrhiza and rhizosphere (the so-called “group effect”).
Phenomena of mutual assistance between plants are possible during “collective defense” from phytophages that exhibit excessive high activity and can seriously damage plants. In this case, after the start of active consumption by phytophages, biochemical reactions occur in plants and the concentration of substances that reduce their palatability (cyanides, etc.) increases. Cases have been described in which individuals attacked by phytophages released signal substances into the atmosphere (the “I’m being eaten” signal), which caused an increase in the formation of cyanide in those individuals that were not yet damaged.
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Competition is the competition between organisms of the same trophic level (between plants, between phytophages, between predators, etc.) for the consumption of a resource available in limited quantities.
Competition for the consumption of resources plays a special role 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 cases where intraspecific competition is more intense than interspecific competition, and vice versa. At the same time, the intensity of competition within and between populations can vary depending on the different conditions. If conditions are unfavorable for one of the species, then competition between its individuals may increase. In this case, it may be displaced (or more often, displaced) by a species for which these conditions turned out to be more suitable.
However, in multispecies communities, “dueling” pairs most often do not form, and competition is diffuse: many species simultaneously compete for one or several environmental factors. “Duelists” can only be mass species of plants that share the same resource (for example, trees - linden and oak, pine and spruce, etc.).
Plants may compete for light, for soil resources, and for pollinators. On soils rich in mineral nutrition resources and moisture, dense, closed plant communities are formed, where light is the limiting factor for which plants compete.
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. In this case, competitors of large ungulates can be insects like locusts or mouse-like rodents, which are capable of destroying most of the grass stand during the years of mass reproduction. Predators compete for prey.
Since the amount of food depends not only on environmental conditions, but also depending on the area where the resource is reproduced, competition for food can develop into competition for the occupied space.
As in the relationships between individuals of the same population, competition between species (their populations) can be symmetrical or asymmetrical. Moreover, a situation where environmental conditions are equally favorable for competing species is quite rare, and therefore relations of asymmetric competition arise more often than symmetric ones.
When resources fluctuate, as is usual in nature (moisture or mineral nutrition elements for plants, primary biological production for different types of phytophages, density of prey populations for predators), different competing species alternately gain advantages. This also does not lead 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 experience deterioration of environmental conditions with a decrease in the level of metabolism or even a transition to a dormant state.
The outcome of the competition is also influenced by the fact that a population that has more individuals and will, accordingly, more actively reproduce “its army” (the so-called mass effect) has a greater chance of winning the competition.
23. Relationship between plant and phytophage and the prey is the predator
RELATIONSHIP "PLANT-PHYTOPHAGE".
The “phytophage-plant” relationship is the first link the food chain, in which matter and energy accumulated by producers are transferred to consumers.
It is equally “unprofitable” for plants to be eaten completely 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:
– protect themselves from phytophages with spines, form rosette forms with leaves pressed to the ground, inaccessible to grazing animals;
– protect themselves from complete grazing by biochemical means, producing toxic substances when eating increases, which make them less attractive to phytophages (this is especially typical for slowly growing patients). In many species, when they are eaten, the formation of “unpalatable” substances increases;
– emit odors that repel phytophages.
Protection from phytophages requires significant energy expenditure, and therefore tradeoff can be traced in the “phytophage-plant” relationship: 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 more it is less attractive to phytophages.
At the same time, these means of protection do not ensure 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 onset 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 may generally recover;
– in the savanna, a decrease in the consumption of tree shoots by branch-eating animals (antelopes, giraffes, etc.) leads to the fact that their crowns close together. As a result, fires become more frequent and trees do not have time to recover; the savanna degenerates into thickets of bushes.\
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 short-term outbreaks in the density of phytophage populations and temporary suppression of plant populations occur quite often, followed by a decrease in the density of phytophage populations.
RELATIONSHIP "VICTIM-PREDATOR".
The “predator-prey” relationship represents the links in the process of transfer of matter and energy from phytophages to zoophages or from lower-order predators to higher-order predators.
As in the “plant-phytophage” relationship, a situation in which all victims are eaten by predators, which ultimately leads to their death, is not observed in nature.
Ecological balance between predators and prey is maintained special mechanisms, excluding the complete extermination of victims.
So victims can:
- run away from a predator.
In this case, as a result of adaptation, the mobility of both victims and predators increases, which is especially typical for steppe animals that have nowhere to hide from their pursuers (“Tom and Jerry principle”);
– acquire protective painting(“pretend” to be leaves or twigs) or, on the contrary, bright (for example, red color, 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 itself in the leaves in summer, and in winter against the background white snow;
– spread in groups, which makes searching for and catching them more energy-intensive for the predator;
- hide in shelters;
– move to active defense measures (herbivores with 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 prey, but also a sense of smell, which allows them to determine the location of the prey by smell.
At the same time, they themselves do everything possible to avoid detection of their presence. This explains the cleanliness of small cats, which spend a lot of time toileting and burying excrement to eliminate odors.
With intensive exploitation of phytophagous populations, people often exclude predators from ecosystems (in Great Britain, 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 the predator is performed by the person himself, removing part of the individuals of the phytophage population.
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Competition is typical occurrence for wildlife. It is caused by the struggle for resources. But if we talk about intraspecific competition, it should be noted that this type competition is the most intense.
This is, first of all, due to the fact that individuals of the same species need some strictly defined resource, which individuals of another species may not need. 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 the 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 shoots 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 prevents another from occupying an existing habitat and using its resource. The first form of competition is called fierce competition, and the second is called 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 becomes overcrowded, this type of competition can lead to the death of the entire population of offspring at a certain age stage.
The rivalry looks a little different. For example, if there are 100 hollows in some forest area 150 pairs of birds claim, then it becomes obvious that 50 pairs will not be able to establish their nests in this territory. Therefore, the only possible option for producing offspring may 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 or those who are more fortunate due to a combination of circumstances survive. Thus, the most ordinary sprout, which sprouted a little earlier than its fellow tribesmen, will subsequently obscure the low-growing specimens.
Ignorance of the laws related to intraspecific competition can lead to dire consequences. For example, in agricultural production, a significant excess of seed sowing rates per unit area can lead to complete loss harvest. Numerous plants exhausted by competition will simply not be able to produce a harvest, but even survive to reproductive age.
Competition is directly related to the concept of an ecological niche, which represents not only certain environmental conditions to which an organism is adapted, but also a way of life and a method of obtaining food. Often this term is applied mainly to interspecific competition, but in fact the ecological niche is characteristic even of each individual organism of the same species.
One more interesting factor in intraspecific competition is the size of the bodies of organisms. Thus, the growth of fish does not stop even after reaching sexual maturity, and is determined by food reserves. The American ecologist R. Whittaker gives the following example in this regard. There are two identical ponds. 100 fry are released into the first, and 50 into the second. As a result, after an equal period of time, the size of the fish in the first pond can be half as large as in the second. However, the weight of fish in both the first and second ponds may be approximately the same.
In addition to uniform depletion of resources, intraspecific competition can also lead to intoxication of the entire population. This happens because the excretion products of organisms of the same species are, in fact, poison for them. For example, in a plant community, root secretions of some plant species can provide nutrients for other plant species. Therefore in wildlife It is rare to find communities represented by a single species.
Grandfather Darwin noted in his evolutionary theory that the severity of the struggle for existence in to the greatest extent manifests itself precisely among representatives of the same species. And although in the sphere latest achievements In genetics and a number of other biological sciences, an increasing number of comments and claims are arising to the theory of Charles Darwin, however, so far no one has come up with anything more significant in biology.
According to the Ukrainian ecologist V. Kucheryavyi: “Intraspecific competition has many negative consequences. It not only depletes resources and leads to intoxication environment, but also promotes self-injury 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 the creation of 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 the same species of the same 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, it turns out that Homo sapiens, in fact, is not such, but is a typical biological species. Obviously this is not the case. But the main flaw of this teaching is that it does not try to change anything in better side, 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 intraspecific and interspecific human competition is so depleting the resources of the biosphere 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 about this in one of the following publications. In short, we can say the following. Man is a social being, therefore a number of biological laws are neutralized due to artificial social institutions and established norms of behavior. At the same time, one should not underestimate the biological laws in life human species. We can say that many social mechanisms are just 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, the biological laws of survival manifest themselves in their entirety.
The world of wildlife is amazingly diverse. The same can be said about the relationships between all species inhabiting the planet. Like people, animals can exploit, interfere with each other, or not interact at all. Examples of competition in nature are a fairly common and natural phenomenon. Which of them are the most striking and interesting?
Examples of competitive relationships in nature
Interspecific competition has always been difficult to demonstrate in field conditions, and therefore not many concrete examples can be observed. Just because two species use the same resource does not mean they compete. There is simply no need for animals to enter into a fight where everything they need to survive is available in unlimited quantities. Similar examples can be found in natural systems.
To say that species compete, they must occupy the same ecosystem and share a common resource, and as a result this must lead to a decline in the number of one of the populations or even to its complete destruction or expulsion. It is generally much easier to demonstrate interference competition. This is when one species directly interferes with another species' access to a limited resource and this results in decreased survival.
One example of competition between organisms in nature is the Argentine ant. Its homeland is South America, and it is one of the the worst kinds invasive ants worldwide. When a colony finds a food resource, they physically and chemically defend it, preventing the native ants from accessing the food resource. They often attack and displace other colonies of their fellows in the area. This leads to a decrease in ant populations. Because they physically interact with other ant colonies, this classic example interspecific competition in nature.
Invisible competition
It is much more difficult to detect examples of competition in nature in animals that do not directly interact with each other. Turtles only eat bushes that they can reach by craning their necks. Goats also eat bushes, but they have a wider choice than turtles. As a result, the latter get less of the vegetation they need to survive and thrive. This example of interspecific competition in nature proves the fact that some animals can reduce the numbers of others even without direct physical interaction.
Exploitation and interference (interference)
Interspecific competition occurs when different types species in an ecosystem compete for the same resources: food, shelter, light, water and other important needs. Such a fight can reduce the number specific type Moreover, an increase in the population of competitors also tends to limit the growth of a particular species. Thus, competition can occur in two ways at the level of individual organisms, namely: exploitative competition and interference competition.
Examples of competition in nature of the first type include often invisible competition for limited resources. As a result of using them a certain type they become insufficient for others. Intervention or interference means direct interaction to obtain resources.
Examples of intraspecific competition in nature, as well as interspecific competition, may include the struggle between predators for prey. Thus, a violent confrontation can arise within a species (between two tigers) and between several species (between a lion and a hyena).
Possible effects
- As a result, there may be limitations in population sizes, as well as changes in communities and species evolution.
- According to the principle of competitive exclusion, no two species that use the same limited resources in the same way and in the same space can exist together.
- Although local extinction is rare compared to competitive exclusion and niche differentiation, it also occurs.
Examples of competitive relationships
In a dense forest, interspecific competition may occur between tree-like plants. This is due to the fact that when there is mixed species trees, some may have easier access to resources than others. For example, taller trees are able to absorb more sunlight, making it less accessible to more low species trees.
Wild animals such as lions and tigers are also prime examples of competition in nature. They hunt the same prey, which may cause less food availability for one of them. In addition, spotted hyenas compete with African lion for food. The same thing happens with brown bears and tigers. Zebras and gazelles fight for grass.
Competitive relationships can be seen in the oceans, such as sponges and corals vying for space. In desert areas, the coyote and rattlesnake fighting fiercely for food and water. Interspecific competition is also observed in small animals such as squirrels and chipmunks, which tend to compete for nuts and other foods.
Where both organisms live in the same niche and are in competition for resources or space, there will inevitably be a negative outcome for each organism as the available resource for both parties will decrease.
Intraspecific struggle for existence
This competition is the most fierce and particularly stubborn. This confrontation involves oppression and violent displacement, expulsion or destruction of less adapted individuals. Nature does not like the weak in the struggle for resources and living space. Fights for the female during the mating season are considered one of the bloodiest.
Examples of competition in nature can be very different, including competition when choosing a sexual partner for procreation (deer), struggle for living space and food (a stronger crow will peck a weaker one), and so on.
Interspecies struggle for existence
If individuals of different species fight for something directly or indirectly, then here we're talking about about interspecific competition. Particularly stubborn opposition is observed between closely related creatures, for example:
- Rat gray displaces the black one from her living space.
- The missle thrush is causing a decline in the song thrush population.
- The Prusak cockroach successfully surpasses and infringes on its black relative.
Competition and the struggle for existence are important driving forces of evolution. Natural selection and hereditary variability play an important role in this. It is difficult to imagine how diverse and complex the relationships are between the living beings that inhabit our planet. Intraspecific and interspecific competition are of great, if not decisive, importance in the formation of biological diversity and regulation numerical strength populations.
Relationships between various organisms, in which they begin to compete with each other - this is competition. The subject area does not matter. In biological relationships, this is a type of biotic relationship. Organisms compete to consume limited resources. There are other types of competition, such as economic competition.
Rivalry in nature
Intraspecific competition is the competition between individuals of the same species for the same resources. Thus, self-regulation of a population is influenced by intraspecific competition. Examples of such competition: the nesting site of birds of the same species, competition 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: fox and wolf hunting a hare) is very numerous. Predators compete for food. They rarely come into direct confrontation. As a rule, the failure of one turns into success for the other.
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 struggle for water during drought, when predators have a bad year and they fight for prey.
IN different conditions the intensity of competition between and within populations may vary. But there are no fundamental differences between types of rivalry. It happens that intraspecific competition is more intense than interspecific competition. It happens the other way around. If conditions are unfavorable for one species, they may be suitable for another. In this case, one species is replaced by another.
But in communities where there are many species, competition most often takes place of a diffuse nature (examples: many species simultaneously compete for a certain environmental factor or for several factors at once). Duels occur only among mass species plants 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? Absolutely yes. Plant communities form on soils rich in minerals and moisture. They are thick and closed. Therefore, light for them is limited. They have to compete for it. Pollinating insects 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 and mouse-like rodents, which are capable of mass reproduction destroy most of the grass. Predators compete for prey, and competition for food develops into a struggle for space. This is because food availability depends not only on ecology, but also on area.
Competition between species
As with the relationships between individuals of the same population, interspecific competition (examples were given above) can be asymmetrical and symmetrical. At the same time, asymmetric competition occurs more often. This is due to the fact that identical environmental conditions favorable for rival species are extremely rare.
Fluctuating resources usually occur in nature. Therefore, different competing species take turns gaining advantages. This leads to the development of coexistence of species and their improvement. They alternately find themselves in more or less favorable conditions. In addition, the size of the population influences the outcome of competition. The higher it is, the higher the chances of winning.
Tough fight
If you study everything thoroughly scientific works, which describe competition, one might get the impression that in systems without immigration and emigration, or where they are reduced, there is a very fierce struggle. Such examples of competition between organisms include laboratory cultures, communities on islands or other natural situations with difficult to overcome obstacles to exiting or entering the system. 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 their population density increases, energy costs for life support also increase with it. Then the intraspecific competitive fight. Energy costs increase, the rate of food consumption decreases, and the chances of survival are reduced to a minimum.
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 it will die, but, most likely, it will be small and undeveloped. This will affect the offspring. Therefore, we can conclude that an increase in population density reduces the contribution of an individual to the offspring.
Common features
To summarize, we can say that intraspecific competition has the following common features:
- The rate of resource consumption by individual individuals decreases.
- There are limited resources, due to which there is competition.
- Rival individuals of the same species are not of equal value.
- There is a direct dependence affecting an individual on the number of competitive brothers.
- The result of competition is a decrease in the contribution to the offspring.
Aggressiveness
Competitive struggle within one species can be expressed aggressively (actively). It can be psychological, physical, chemical in nature. It happens that students are asked the question: “What is aggressive intraspecific competition? Give examples of active competition.” Then we can talk about males competing for a female. They behave actively, demonstrate the superiority of their appearance, and 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 viewed 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 competitiveness in the market;
- a criterion that determines the type of industry market.
The market is distinguished different degrees competition excellence. 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 a degree of dependence general conditions in the market on the behavior of its participants, existing separately from each other, but one way or another having certain dependencies.
Competition can be 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 occurs, market structure is analyzed 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 incentive, a stimulus for development. Achieving high results in the economic sphere is only possible if there is competition. One can cite quite a lot of facts confirming this theory from world history.
Perfect Market
In conditions modern market distinguish between perfect and imperfect competition. Freedom of choice is the key concept that perfect competition presupposes. You rarely see examples of such a market. In 1980, product prices fell sharply in the United States Agriculture. At first the farmers blamed government bodies. But when they began to get to the huge commodity exchange in Chicago, they became convinced that the supply was huge and no one could artificially lower prices. Fair competition worked. The market was very uniting big number participants on both sides. Prices were dictated by the market. Only the balance of buyers and sellers influenced the final cost of the goods. Farmers stopped blaming the state and took measures to overcome the crisis.
Perfect competition is the absence of limitations in sellers and buyers. This is the impossibility of controlling prices. With such competition, an entrepreneur can easily enter the industry. Buyers and sellers have equal opportunities to access market information.
An example of perfect competition can be seen by studying the first stages of development of industrial society. At that time, the market was dominated by products of standard type and quality. The buyer could easily evaluate everything. Later, these properties became characteristic only of the raw materials and agricultural markets.
- prices for goods are the same for all buyers and sellers;
- 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 manufacturer can freely enter 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 presupposes the presence of two or more sellers who have the ability 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 price.
The following types of imperfect competition are distinguished:
- monopolistic competition (there are numerous examples, such as the mobile communications market);
- oligopoly;
- monopoly.
Monopolistic competition is the leading form in modern business. With it, quite a lot of entities offer one special product, informational, service or other nature. They are both monopolists and competitors, while possessing real levers of price control for their special products.
Oligopoly refers to an industrial market. Such an example of economic competition where oligopoly occurs can be found in the field of oil and gas production and refining. This competition is characterized by the presence of several largest companies who control significant part production and sales of products. At the same time, these companies seriously compete with each other. Each of them has an independent market policy, which nevertheless depends on competitors. They are forced to reckon with each other. In such a market, a product can be either differentiated or standard. There are significant barriers to entry in this industry.
Monopoly is also a type of industry market. The monopolist is the only one of its kind. It cannot be replaced, not even approximately. He controls the price and volume of production. As a rule, he receives excess profits. A monopoly can be created artificially: exclusive rights, patents, copyrights, ownership of the most important sources of raw materials. It is almost impossible to enter such an industry. The barriers are too high.
Biological interspecific competition is a natural process of struggle between different individuals for space and resources (food, water, light). It occurs when species have similar needs. Another reason for the start of competition is limited resources. If natural conditions provide an excess of food, competition will not arise even between individuals with very similar needs. Interspecific competition can lead to the extinction of a species or its displacement from its previous habitat.
Struggle for existence
In the 19th century, interspecific competition was studied by researchers involved in the formation of the theory of evolution. Charles Darwin noted that canonical example Such a struggle is the coexistence of herbivorous mammals and locusts feeding on the same plant species. Deer eating tree leaves deprive bison of food. Typical rivals are a mink and an otter, driving each other out of contested bodies of water.
The animal kingdom is not the only environment where interspecific struggle is observed; such struggles are also found among plants. It’s not even the above-ground parts that are in conflict, but root systems. Some species suppress others different ways. Soil moisture and minerals are taken away. A striking example of such actions is the activity of weeds. Some root systems use their secretions to change chemical composition soil, which hinders the development of neighbors. In a similar way, interspecific competition manifests itself between creeping wheatgrass and pine seedlings.
Ecological niches
Competitive interaction can be very different: from peaceful coexistence to physical struggle. In mixed plantings, fast-growing trees suppress slow-growing ones. Fungi inhibit bacterial growth by synthesizing antibiotics. Interspecific competition can lead to the demarcation of ecological poverty and an increase in the number of differences between species. Thus, environmental conditions and the totality of connections with neighbors change. is not equivalent to habitat (the space where an individual lives). In this case we are talking about the entire lifestyle. A habitat can be called an “address,” and an ecological niche can be called a “profession.”
In general, interspecific competition is an example of any interaction between species that negatively affects their survival and growth. As a result, rivals either adapt to each other, or one opponent displaces the other. This pattern is typical for any struggle, be it the use of the same resources, predation or chemical interaction.
The pace of the struggle increases when we are talking about species that are similar or belong to the same genus. A similar example of interspecific competition is the story of gray and black rats. Previously, these different species of the same genus lived next to each other in cities. However, due to their better adaptability, gray rats supplanted black rats, leaving them with forests as their habitat.
How can this be explained? They swim better, they are larger and more aggressive. These characteristics influenced the outcome to which the described interspecific competition led. Examples of such collisions are numerous. The struggle between wood thrushes and song thrushes in Scotland was very similar. And in Australia, bees brought from the Old World replaced the smaller native bees.
Exploitation and interference
To understand in what cases interspecific competition occurs, it is enough to know that in nature there are no two species that occupy the same ecological niche. If organisms are closely related and lead a similar lifestyle, they will not be able to live in the same place. When they do take common territory, these species feed on different foods or are active in different time days. One way or another, these individuals necessarily have a different trait, which gives them the opportunity to occupy different niches.
Apparently peaceful coexistence can also be an example of interspecific competition. The relationships of certain plant species provide a similar example. Light-loving species of birch and pine protect spruce seedlings that die in open areas from freezing. This balance is sooner or later upset. Young spruce trees close in and kill new shoots of species that need sun.
Neighborhood of different species of rock nuthatches - another shining example morphological and ecological separation of species, which leads to interspecific competition of biology. Where these birds live near each other, their method of obtaining food and the length of their beaks differ. This distinction is not observed in different habitat areas. Separate question evolutionary doctrine- similarities and differences of intraspecific and interspecific competition. Both cases of struggle can be divided into two types - exploitation and interference. What are they?
During exploitation, the interaction of individuals is indirect. They react to a decrease in the amount of resources caused by the activity of neighboring competitors. consume food to such an extent that its availability is reduced to a level where the rate of reproduction and growth of the rival species becomes extremely low. Other types of interspecific competition are interference. They are demonstrated by sea acorns. These organisms prevent neighbors from attaching to the stones.
Amensalism
Other similarities between intraspecific and interspecific competition are that both can be asymmetrical. In other words, the consequences of the struggle for existence for the two species will not be the same. Such cases are especially common in insects. In their class, asymmetric competition occurs twice as often as symmetric competition. Such an interaction in which one individual adversely affects another, but the other does not have any effect on the opponent is also called amensalism.
An example of such a struggle is known from observations of bryozoans. They compete with each other through fouling. These colonial species live on corals off the coast of Jamaica. The most competitive individuals “defeat” their opponents in the overwhelming majority of cases. These statistics clearly demonstrate how asymmetric types of interspecific competition differ from symmetric ones (in which the opponents' chances are approximately equal).
Chain reaction
Among other things, interspecific competition can cause the limitation of one resource to lead to the limitation of another resource. If a colony of bryozoans comes into contact with a rival colony, then there is a possibility of disruption of the flow and food supply. This, in turn, leads to the cessation of expansion and occupation of new areas.
A similar situation arises in the case of a “war of the roots.” When an aggressive plant shades a rival, the oppressed organism feels a lack of incoming solar energy. Such starvation causes a slowdown in root growth, as well as a deterioration in the use of minerals and other resources in soil and water. Plant competition can influence both from roots to shoots, and vice versa from shoots to roots.
Algae Example
If a species has no competitors, then its niche is considered not ecological, but fundamental. It is determined by the totality of resources and conditions under which an organism can maintain its population. When competitors appear, the view from the fundamental niche falls into the realized niche. Its properties are determined by biological competitors. This pattern proves that any interspecific competition causes a decrease in viability and fertility. In the worst case, neighbors push the organism into that part of the ecological niche where it cannot not only live, but also have offspring. In such a case, the species faces the threat of complete extinction.
Under experimental conditions, fundamental niches diatoms provided by the cultivation regime. It is through their example that it is convenient for scientists to study the phenomenon biological control for survival. If two competing species, Asterionella and Synedra, are placed in the same test tube, the latter will gain a niche suitable for life, while Asterionella will die.
The coexistence of Aurelia and Bursaria gives other results. Being neighbors, these species will have their own realized niches. In other words, they will share resources without fatal harm to each other. Aurelia will concentrate at the top and consume the suspended bacteria. The Bursaria will settle to the bottom and feed on the yeast cells.
Resource Sharing
The example of Bursaria and Aurelia shows that peaceful existence is possible with niche differentiation and resource sharing. Another example of this pattern is the struggle between Galium algae species. Their fundamental niches include alkaline and acidic soils. With the emergence of a fight between Galium hercynicum and Galium pumitum, the first species will be limited to acidic soils, and the second to alkaline soils. This phenomenon in science is called mutual competitive exclusion. At the same time, algae need both alkaline and acidic environments. Therefore, both species cannot coexist in the same niche.
The principle of competitive exclusion is also called the Gause principle after the name of the Soviet scientist Georgy Gause, who discovered this pattern. From of this rule it follows that if two species cannot, due to some circumstances, share their niches, then one will certainly exterminate or supplant the other.
For example, Chthamalus and Balanus coexist next door only for the reason that one of them, due to sensitivity to desiccation, lives exclusively in the lower part of the coast, while the other is able to live in the upper part, where it is not threatened by competition. Balanus pushed out Chthamalus, but were unable to continue their expansion on land due to their physical limitations. Repression occurs under the condition that strong competitor has a realized niche that completely covers the fundamental niche of a weak opponent drawn into a dispute over habitat.
Gause principle
Ecologists are involved in explaining the causes and consequences of biological control. When it comes to a specific example, sometimes it is quite difficult for them to determine what the principle of competitive exclusion is. Such a difficult issue for science is the rivalry between different species of salamanders. If it is impossible to prove that niches are separated (or to prove otherwise), then the operation of the principle of competitive exclusion remains only an assumption.
At the same time, the truth of Gause’s law has long been confirmed by many recorded facts. The problem is that even if niche division occurs, it is not necessarily due to interspecific competition. One of the urgent problems of modern biology and ecology is the causes of the disappearance of some individuals and the expansion of others. Many examples of such conflicts are still poorly studied, which provides a lot of room for future specialists to work on.
Adaptation and repression
The improvement of one species will necessarily lead to a deterioration in the lives of other species. They are connected by one ecosystem, which means that in order to continue their existence (and the existence of their offspring), organisms must evolve, adapting to new living conditions. Most of living beings disappeared not for any reasons of their own, but only due to the pressure of predators and competitors.
Evolutionary race
The struggle for existence has continued on Earth exactly since the first organisms appeared on it. The longer this process lasts, the more it appears on the planet. species diversity and the more diverse the forms of competition themselves become.
The rules of wrestling change constantly. In this they differ from For example, the climate on the planet also changes without stopping, but it changes chaotically. Such innovations do not necessarily harm organisms. But competitors always evolve to the detriment of their neighbors.
Predators improve their hunting methods, and victims improve their defense mechanisms. If one of them stops evolving, this species will be doomed to displacement and extinction. This process is a vicious circle, since some changes give rise to others. The perpetual motion machine of nature pushes life to constantly move forward. Interspecies fight plays the role of the most effective tool in this process.
>> Competitive interactions
1. What kind of struggle is called intraspecific?
2. What type of struggle is called interspecific?
3. What are the features of intra- and interspecific struggle?
IN in a general sense The word "competition" means clash, rivalry, competition. Competition is extremely widespread in nature.
Competitive interactions may concern space, food, light, dependence on predators and other enemies, exposure to disease, and various environmental factors.
It must be borne in mind that simply the use by organisms of the same thing cannot be considered competition. natural resource. We can talk about negative interaction only when this resource is not enough and when its joint consumption adversely affects populations.
Competition is divided into intraspecific and interspecific.
Both intraspecific and interspecific competition can have great importance in the formation of species diversity and regulation number each of them.
Intraspecific competition. The struggle for the same resources that occurs between individuals of the same species is called intraspecific competition. This is an important factor in the self-regulation of populations.
Some organisms, under the influence of intraspecific competition for space, have developed an interesting type of behavior. It is called territoriality.
Territoriality is characteristic of many species of birds, some fish, and other animals.
In birds, the territorial type of behavior manifests itself as follows: At the beginning of the breeding season, the male chooses a habitat (territory) and protects it from invasion by males of the same species. Let us note that the loud voices of males, which we hear in the spring, only signal ownership of the area they like, and do not at all set themselves the task of attracting a female, as is usually believed.
A male who strictly guards his territory has a greater chance of successfully mating and building a nest, whereas a male who is unable to secure a territory will not reproduce. Sometimes the female also takes part in protecting the territory. As a result, in a protected area, the complex task of caring for the nest and young is not disrupted by the presence of other parental pairs.
Thus, territorial behavior can be considered an ecological regulator, since it allows one to equally avoid both overpopulation and underpopulation.
A striking example of intraspecific competition that everyone could see in the forest, the so-called self-thinning in plants.
This process begins with the seizure of territory. For example, somewhere in an open place, not far from a large spruce tree that produces many seeds, several dozen seedlings appear - small fir trees. The first task has been completed - the population has grown and captured the territory it needs to survive. Thus, territoriality in plants is expressed differently than in animals: a site is occupied not by an individual, but by a group.
Young trees grow, simultaneously shading and suppressing herbaceous plants located under their crowns (this is already interspecific competition). Over time, an inevitable difference in growth appears between the trees - some, weaker, lag behind, others overtake. Since spruce is a very light-loving species (its crown absorbs almost all the light falling on it), weaker fir trees begin to increasingly experience shading from the taller ones and gradually dry out and die.
In the end, after many years, in a clearing, from several dozen fir trees, only two or three trees (or even one) remain - the strongest individuals of the entire generation (Fig. 128).
High animal density is a depressing factor that reduces reproduction even in abundance food resources. For example, when there are a large number of tadpoles, those that grow faster release substances into the water that suppress the development of those tadpoles that grow more slowly.
Interspecific competition.
Competition between individuals of different species is extremely widespread in nature and affects almost every species, since it is rare that a species does not experience at least a little pressure from organisms of other species. However, ecology considers interspecific competition in a specific, narrow sense - only as mutually negative relations between closely related or ecologically similar species living together.
The forms of manifestation of interspecific competition can be very different: from brutal struggle to almost peaceful coexistence. But, as a rule, of two species with the same ecological needs, one necessarily displaces the other.
A classic example of interspecific competition are those described by Russian biologist G, F. Gause experiments. In these experiments, cultures of two species of slipper ciliates with similar feeding patterns were placed separately and together in vessels with hay infusion. Each species, placed separately, reproduced successfully, reaching optimal numbers. When both cultures were placed in one vessel, the number of one of the species gradually decreased and it disappeared from the infusion (Fig. 129).
The rule derived from these experiments, the so-called Gause principle, is that two ecologically identical species cannot coexist. Competition is especially severe between organisms that have similar ecological needs.
As a result of competition, only those species that manage to diverge at least slightly in their environmental requirements coexist in the community. Thus, insectivorous birds that feed on trees avoid competition with each other thanks to different character searching for prey on different parts of the tree.
Thus, interspecific competition can have two results: either the displacement of one of the two species from the community, or the divergence of both species into ecological niches. Competitive relations are one of the most important factors in the formation of species composition and regulation of population numbers in a community.
Interspecific competition may play a role important role in shaping the appearance of the natural community. By generating and consolidating the diversity of organisms, competition helps to increase the sustainability of communities, more effective use available resources.
Intraspecific competition. Interspecific competition.
1. What types of competition do you know?
2. What is territoriality? What role does she play in the community?
3. Why can species with similar lifestyles often live in the same territory?
4. How can one explain the long-term coexistence of competing species in nature?
5. What type of competition does it have? highest value in the formation of the species composition of natural communities?
Observe the manifestations of intraspecific and interspecific competition in nature. Try to explain what is their difference and what is their similarity.
Kamensky A. A., Kriksunov E. V., Pasechnik V. V. Biology 10th grade
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