Relationships between animals. Intraspecific and interspecific competition
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 fundamental differences there is no rivalry between types. 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 factor environment 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 it competition between plants for light, for soil resources, for pollinators? Absolutely yes. On soils rich in minerals and moisture, they form plant communities. 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, large-ungulates can compete with insects such as locusts and mouse-like rodents, which are capable of destroying most of the grass when they reproduce en masse. 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 intraspecific competition increases. 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 cash buyer by satisfying his needs. When structural competition occurs, analysis occurs 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 competition 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. Achieve high results in economic sphere 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 - that's it key concept, which assumes perfect competition. You rarely see examples of such a market. In 1980, product prices fell sharply in the United States Agriculture. At first, farmers blamed government agencies. 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 united a very large number of participants from 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. On 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 its own 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.
>> 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 a general sense, the word “competition” means confrontation, 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 be of 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 important factor self-regulation of populations.
In some organisms, under the influence intraspecific competition formed for space interesting guy 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 selects 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 oppressing those under their crowns herbaceous plants(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 densities are a suppressive factor, reducing reproduction even when food resources are abundant. 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.
Competition between individuals different types 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 fierce 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 due to the different nature of searching for prey on different parts 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- one of the most important factors in the formation species composition and regulation of population numbers in a community.
Interspecific competition may play a role important role in shaping the appearance natural community. By generating and consolidating the diversity of organisms, competition helps to increase the sustainability of communities and more efficient use of 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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Predation is direct food relationships between organisms in which some organisms are destroyed by other organisms. Examples: fox eating hares, tit eating caterpillars.
Competition is a type of relationship that arises between species with similar ecological needs because of food, territory, etc. Example: competition between moose and bison living in the same forest because of food. The negative impact of competition on both competing species (for example, a decrease in the number of moose and bison due to lack of food).
Symbiosis is a type of interspecies relationship in which both organisms receive mutual benefit. Examples of symbiosis: hermit crab and sea anemone, nodule plants and bacteria, cap mushrooms and trees, lichens (symbiosis of fungus and algae).
Among the huge variety of relationships among living beings, certain types of relationships are distinguished that have much in common among organisms of different systematic groups.
Symbiosis
Symbiosis1 - cohabitation (from the Greek sim - together, bios - life) is a form of relationship from which both partners, or at least one, benefit.
Symbiosis is divided into mutualism, protocooperation and commensalism.
Mutualism2 is a form of symbiosis in which the presence of each of the two species becomes obligatory for both, each of the cohabitants receives relatively equal benefits, and the partners (or one of them) cannot exist without each other.
A typical example of mutualism is the relationship between termites and flagellated protozoa that live in their intestines. Termites eat wood, but they do not have enzymes to digest cellulose. Flagellates produce such enzymes and convert fiber into sugars. Without protozoa - symbionts - termites die of starvation. In addition to a favorable microclimate, the flagellates themselves receive food and conditions for reproduction in the intestines.
Protocooperation3 is a form of symbiosis in which coexistence is beneficial for both species, but not necessarily for them. In these cases, there is no connection between this particular pair of partners.
Commensalism is a form of symbiosis in which one of the cohabiting species receives some benefit without bringing any harm or benefit to the other species.
Commensalism, in turn, is subdivided into tenantry, co-feeding, and freeloading.
"Living"4 is a form of commensalism in which one species uses another (its body or its home) as a shelter or home. Of particular importance is the use of reliable shelters for the preservation of eggs or juveniles.
The freshwater bitterling lays its eggs in the mantle cavity of bivalve mollusks - toothless. The laid eggs develop in ideal conditions supply of clean water.
"Community eating"5 is a form of commensalism in which several species consume different substances or parts of the same resource.
"Freeloading"6 is a form of commensalism in which one species consumes the leftover food of another.
An example of the transition of freeloading into closer relationships between species is the relationship between the sticky fish, which lives in tropical and subtropical seas, with sharks and cetaceans. The front dorsal fin of the sticker has been transformed into a suction cup, with the help of which it is firmly held on the surface of the body of a large fish. The biological meaning of the attachment of sticks is to facilitate their movement and settlement.
Neutralism
Neutrality7 is a type of biotic relationship in which organisms living together in the same territory do not affect each other. In neutralism, individuals of different species are not directly related to each other.
For example, squirrels and moose in the same forest do not contact each other.
Antibiosis
Antibiosis is a type of biotic relationship when both interacting populations (or one of them) experience bad influence each other.
Amensalism8 is a form of antibiosis in which one of the cohabiting species oppresses another, receiving neither harm nor benefit from it.
Example: light-loving herbs growing under a spruce suffer from severe darkening, while they themselves do not affect the tree in any way.
Predation9 is a type of antibiosis in which members of one species feed on members of another species. Predation is widespread in nature among both animals and plants. Examples: carnivorous plants; lion eating antelope, etc.
Co-competition is a type of biotic relationship in which organisms or species compete with each other to consume the same, usually limited, resources. Competition is divided into intraspecific and interspecific.
Intraspecific co-competition10 is competition for the same resources that occurs between individuals of the same species. This is an important factor in self-regulation of the population. Examples: Birds of the same species compete for nesting sites. During the breeding season, males of many mammal species (for example, deer) compete with each other for the opportunity to start a family.
Interspecific competition11 is competition for the same resources that occurs between individuals of different species. Examples of interspecific competition are numerous. Both wolves and foxes hunt hares. Therefore, competition for food arises between these predators. This does not mean that they directly come into conflict with each other, but the success of one means the failure of the other.
For example, lampreys attack cod, salmon, smelt, sturgeon and others large fish and even whales. Having attached itself to the victim, the lamprey feeds on the juices of its body for several days, even weeks. Many fish die from the numerous wounds it inflicts.
All of the listed forms of biological connections between species serve as regulators of the number of animals and plants in the community, determining its stability.
Various shapes interactions between individuals and populations:
Lesson 14, 15
Practical work № 1, 2 Description anthropogenic changes in the natural landscapes of your area
Not all relationships between populations are ecologically equivalent: some of them are rare, others are optional, and others, such as competition, are the main mechanism for the emergence of ecological diversity.
Competition(from Latin concurrere - collide) - interaction in which two populations (or two individuals) in the struggle for the conditions necessary for life influence each other negatively, i.e. mutually oppress each other.
It should be noted that competition can also manifest itself when a resource is sufficient, but its availability is reduced due to the active opposition of individuals, which leads to a decrease in the survival rate of competing individuals.
Organisms that can potentially use the same resources are called competitors. Plants and animals compete with each other not only for food, but also for moisture, living space, shelter, nesting sites - for everything on which the well-being of the species may depend.
Intraspecific competition
If competitors belong to the same species, then the relationship between them is called intraspecific competition. Competition between individuals of the same species is the most intense and severe in nature, since they have the same needs for environmental factors. Intraspecific competition can be observed in penguin colonies, where there is a struggle for living space. Each individual maintains its own section of territory and is aggressive towards its neighbors. This leads to a clear division of territory within the population.
Intraspecific competition almost always occurs at one stage or another in the existence of a species; therefore, in the process of evolution, organisms have developed adaptations that reduce its intensity. The most important of them are the ability to disperse descendants and protect the boundaries of an individual site (territoriality), when an animal defends its nesting site or a specific area. Thus, during the breeding season of birds, the male protects a certain territory, into which, except for his female, he does not allow any individual of his species. The same picture can be observed in some fish.
Interspecific competition
If competing individuals belong to different species, then this interspecific competition. The object of competition can be any resource whose reserves in a given environment are insufficient: a limited distribution area, food, a site for a nest, nutrients for plants.
The result of competition may be the expansion of the distribution area of one species due to the reduction in numbers or extinction of another. An example is an active extension with late XIX V. range of the long-clawed crayfish, which gradually captured the entire Volga basin and reached Belarus and the Baltic states. Here he began to displace related species- broad-clawed crayfish.
Competition can be quite intense, for example in the fight for nesting territory. This type is called direct competition. In most cases, these conflicts occur between individuals of the same species. However, often the competitive struggle is outwardly bloodless. For example, many predatory animals that compete for food are not directly affected by other predators, but indirectly, through a decrease in the amount of food. The same thing happens in the plant world, where, during competition, some influence others indirectly, through interception nutrients, sun or moisture. This type is called indirect competition.
Competition is one of the reasons that two species, slightly different in the specifics of nutrition, behavior, lifestyle, etc., rarely coexist in the same community. Studies of the causes and consequences of interspecific competition have led to the establishment of special patterns in the functioning of individual populations. Some of these patterns have been elevated to the rank of laws.
Studying the growth and competitive relationships of two species of ciliated ciliates, Soviet biologist G.F. Gause conducted a series of experiments, the results of which were published in 1934. Two species of ciliates - Paramecium caudatum and Paramecium aurelia - grew well in monoculture. Their food was bacterial or yeast cells growing on regularly added oatmeal. When Gause placed both species in the same container, each species initially increased in number rapidly, but over time P. aurelia began to grow at the expense of P. caudatum until the second species disappeared completely from the culture. The period of disappearance lasted about 20 days.
Thus, G.F. Gause formulated law (principle) of competitive exclusion, which states: two species cannot exist in the same habitat (in the same area) if their ecological needs are identical. Therefore, any two species with identical ecological needs are usually separated in space or time: they live in different biotopes, in different forest layers, live in the same body of water at different depths, etc.
An example of competitive exclusion is the change in the numbers of roach, rudd and perch when they live together in lakes. Over time, roach displaces rudd and perch. Research has shown that competition affects the fry stage when the feeding spectra of the juveniles overlap. At this time, roach fry turn out to be more competitive.
In nature, species competing for food or space often avoid or reduce competition by moving to another habitat with acceptable conditions, or by switching to more inaccessible or difficult-to-digest food, or by changing the time (place) of foraging. Animals are divided into diurnal and nocturnal (hawks and owls, swallows and the bats, grasshoppers and crickets, different kinds fish that are active in different time days); lions hunt larger animals, and leopards hunt smaller ones; For tropical forests The distribution of animals and birds by tiers is characteristic.
An example of the division of living space is the division of food spheres between two species of cormorant - great and long-nosed. They live in the same waters and nest on the same cliffs. Observations have shown that the long-billed cormorant catches fish swimming in upper layers water, while the great cormorant forages mainly at the bottom, where it catches flounder and hip invertebrates.
Spatial separation can also be observed among plants. Growing together in one habitat, plants extend their root systems on different depths, thereby separating the absorption regions nutrients and water. The depth of penetration can vary from a few millimeters in root-litter plants (such as wood sorrel) to tens of meters in large trees.
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. This resource is usually limited. This could be food, territory, light, and the like. There are two types of competition: intraspecific, when individuals of different species or genera become competitors, and interspecific.
Intraspecific competition occurs when needs certain type organisms exceed the reserves of the necessary resource and some individuals of the species do not receive enough of it. Competition increases as the population of the species increases. There are two forms: a) exploitative, when the individuals that compete do not interact directly with each other, but each receives that part of the resource that is left to it from the others; b) interference, when one individual actively prevents another from using a resource (protection of “their” territory by animals, colonization of a biotope by plants, etc.). Intraspecific competition affects fertility, mortality, growth and abundance (density). The combination of these effects of competition affects the increase in 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 habit of the crown, causes drying out and falling off of lateral branches; the formation of the apical crown can be better observed in the example of pine, spruce and other coniferous and broad-leaved species.
Interspecific competition gains 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 the competitor. Competition causes oppression or complete displacement of one species from an ecological niche and its replacement by 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 exploitative and interference, or direct and indirect. Both forms are found in both plants and animals. An example of a direct effect on competitors is the shading of one species by another. Some plants secrete into the soil toxic substances, and this suppresses 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 negatively affect other plants. This toxic effect of some plants on others is called allelopathy. Indirect competition is not as noticeable as direct competition, and its consequences appear after prolonged exposure in the form of differential survival and reproduction.
