Biological interspecies 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, there will be no fight even between individuals with very similar needs. Interspecific competition can lead to the extinction of a species or its displacement from its former 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 the canonical example of such a struggle is the coexistence of herbivorous mammals and locusts that feed on the same plant species. Deer eating leaves of trees deprive bison of food. Typical rivals are mink and otter, driving each other out of contested waters.
The animal kingdom is not the only environment where there is interspecies competition. Examples of such struggle are also found among plants. Not even the above-ground parts are in conflict, butroot systems. Some species oppress others in different ways. Soil moisture and minerals are taken away. A striking example of such actions is the activity of weeds. Some root systems, with the help of their secretions, change the chemical composition of the soil, which inhibits the development of neighbors. In a similar way, interspecific competition between creeping wheatgrass and pine seedlings is manifested.
Ecological niches
Competitive interaction can be very different: from peaceful coexistence to physical struggle. In mixed plantings, fast-growing trees oppress slow-growing ones. Fungi inhibit bacterial growth by synthesizing antibiotics. Interspecific competition can lead to demarcation of ecological poverty and increase in the number of differences between species. So, the environmental conditions, the totality of relations with neighbors are changing. An ecological niche is not equivalent to a habitat (the space where an individual lives). In this case, we are talking about the whole way of life. A place can be called an “address” and an ecological niche a “profession.”
Competition of similar species
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 characteristic of any struggle, whether it is the use of the same resources, predation or chemical interaction.
The pace of the struggle increases when it comes to similar or belonging to the same genustypes. A similar example of interspecific competition is the story of gray and black rats. Previously, these different species of the same genus coexisted with each other in cities. However, due to their better adaptability, gray rats displaced black rats, leaving them with forests as their habitat.
How can this be explained? Gray rats swim better, they are larger and more aggressive. These characteristics influenced the outcome of the described interspecific competition. There are many examples of such collisions. Very similar was the fight between mistle thrushes and song thrushes in Scotland. And in Australia, bees brought from the Old World have supplanted 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 would 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 occupy a common territory, these species feed on different foods or are active at different times of the day. One way or another, these individuals necessarily have a different trait that gives them the opportunity to occupy different niches.
Externally peaceful coexistence can also be an example of interspecies competition. The relationships of certain plant species provide such an example. Light-loving species of birch and pine protect spruce seedlings dying in open places from freezing. This balance sooner orbroken late. Young spruces close up and kill new shoots of species that need the sun.
The proximity of different types of rock nuthatches is another vivid example of the morphological and ecological separation of species, which leads to interspecific competition in biology. Where these birds live near each other, their way of foraging and beak length differ. In different habitats, this distinction is not observed. A separate issue of evolutionary doctrine is the similarities and differences of intraspecific, interspecific competition. Both cases of struggle can be divided into two types - exploitation and interference. What are they?
In exploitation, the interaction of individuals is indirect. They respond to a decrease in the amount of resources caused by the activity of competing neighbors. Diatoms 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 shown by sea acorns. These organisms prevent neighbors from attaching to rocks.
Amensalism
Another similarity between intraspecific and interspecific competition is that both can be asymmetric. In other words, the consequences of the struggle for existence for the two species will not be the same. This is especially true in insects. In their class, asymmetric competition occurs twice as often as symmetrical competition. An interaction in which onean individual adversely affects another, and that 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 by fouling. These colonial species live on corals off the coast of Jamaica. Their most competitive individuals "defeat" opponents in the vast majority of cases. This statistic clearly demonstrates how asymmetric types of interspecies competition differ from symmetrical ones (in which the chances of rivals are approximately equal).
Chain reaction
Among other things, interspecies competition can cause a limitation of one resource to result in a 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 intake. This, in turn, leads to the cessation of growth and the occupation of new areas.
A similar situation occurs in the case of the "war of the roots". When an aggressive plant obscures a rival, the oppressed organism feels a lack of incoming solar energy. This starvation causes stunted root growth as well as poor utilization of minerals and other resources in soil and water. Plant competition can affect 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 totalityresources 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 rivals. This pattern proves that any interspecific competition is the cause of a decrease in viability and fertility. In the worst case, the neighbors force the organism into that part of the ecological niche where it cannot not only live, but also acquire offspring. In such a case, the species faces the threat of its complete extinction.
Under experimental conditions, the fundamental niches of diatoms are provided by the cultivation regime. It is on their example that it is convenient for scientists to study the phenomenon of the biological struggle for survival. If two competing species of Asterionella and Synedra are placed in the same tube, the latter will get a habitable niche, and Asterionella will die.
The coexistence of Aurelia and Bursaria gives other results. Being neighbors, these species will get 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 suspended bacteria. Bursaria will settle to the bottom and feed on the yeast cells.
Sharing resources
The example of Bursaria and Aurelia shows that a peaceful existence is possible with the differentiation of niches and the division of resources. Another example of this pattern is the struggle of Galium algae species. Their fundamental niches include alkaline and acidic soils. With the emergence of a struggle 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. It follows from this rule that if two species cannot, due to some circumstances, divide their niches, then one will certainly exterminate or displace the other.
For example, the sea acorns Chthamalus and Balanus coexist in the neighborhood only because one of them, due to its sensitivity to drying, 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 rivalry. Balanus pushed out Chthamalus, but were unable to continue their expansion on land due to their physical handicaps. Crowding out occurs on the condition that a strong competitor has a realized niche that completely overlaps the fundamental niche of a weak opponent drawn into a dispute over a habitat.
Gause principle
Explanation of the causes and consequences of biological control is carried out by ecologists. 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 complex issue for science is the rivalry of different species.salamander. If it is impossible to prove that the niches are separated (or prove otherwise), then the principle of competitive exclusion is only a guess.
At the same time, the truth of the Gauze pattern has long been confirmed by many recorded facts. The problem is that even if niche division does occur, it is not necessarily due to interspecies struggle. One of the urgent tasks of modern biology and ecology is to determine the causes of the disappearance of some individuals and the expansion of others. Many examples of such conflicts are still poorly understood, which gives a lot of space for future specialists to work with.
Accommodation and displacement
The life of every organism is highly dependent on the host-parasite and prey-predator relationships. It is formed not only by abiotic conditions, but also by the influence of other plants, animals and microorganisms. It is impossible to get rid of or hide from these connections, since absolutely everything in nature is interconnected.
Improvement of one species will necessarily lead to a deterioration in the life of other species. They are connected by one ecosystem, which means that in order to continue their existence (and the existence of offspring), organisms must evolve, adapting to new living conditions. Most of the living creatures disappeared not for some reason of their own, but only due to the pressure of predators and competitors.
Evolution Race
The struggle for existence continues onEarth exactly since the first organisms appeared on it. The longer this process lasts, the more species diversity appears on the planet and the more diverse the forms of competition themselves become.
The rules of wrestling change all the time. In this they differ from abiotic factors. For example, the climate on the planet also changes without stopping, but it changes randomly. Such innovations do not necessarily harm organisms. But competitors always evolve to the detriment of their neighbors.
Predators improve their hunting methods, prey improve the mechanisms of this protection. If one of them ceases to evolve, this species will be doomed to displacement and extinction. This process is a vicious circle, as some changes give rise to others. The perpetual motion machine of nature pushes life to a constant movement forward. Interspecific struggle in this process plays the role of the most effective tool.
