Demecology is a scientific discipline that examines the diversity of relationships between living organisms in different populations. One form of such interaction is interspecific competition. In this article, we consider its features, patterns of the struggle for territory, food, and other abiotic factors in organisms living in natural and artificial biogeocinosis.
Type and its ecological characteristic
During the historical development, biological taxa (groups with some commonality) adapt to the abiotic and biotic factors of nature. The former include climate, the chemical composition of soil, water and air, etc., and the latter include the impact of the vital activity of some species on others.
Individuals of one species are unevenly distributed in certain areas of biotopes. Their clusters are called populations. Communities of one species are constantly in contact with populations of other species. This determines its position in the biogeocenosis, which is called the ecological niche.
Interspecific competition, an example of which we will consider in the article, takes place directly in places where communities of various species overlap and can lead to the extinction of the population of one of them. For example, in the experiments of the Russian scientist G. Gauze, two types of ciliates developed on the same nutrient medium. One of them began to actively multiply and grow at the expense of the other. As a result, the weaker species completely eliminated (extinct) within 20 days.
What results in overlapping areas
If the habitats of two different species in some parts of the biotope merge, then between individuals there are quite strong differences in the external structure, puberty and mating. They are called feature bias.
On the periphery of the range, where organisms of only one species live, their populations are convergent with communities represented by individuals of another species. It should be noted that in the second case, interspecific competition between populations is practically absent. The example of finch observed by C. Darwin in the Galapagos Islands during his round-the-world trip on the Beagle frigate is a vivid confirmation of this.
Law of Competitive Exclusion
The aforementioned scientist G. Gauze formulated an important ecological regularity: if the trophic and other needs of populations of two different species coincide, then such taxa become competing. This excludes their further coexistence on the same range, since interspecific competition arises between them. An example that illustrates it is the fluctuation in the abundance of perch, rudd and roach, feeding in the same body of water. Roach fry are more active and gluttonous, therefore they successfully replace young perch and rudd.
Sympatric and allopathic taxa
They arose as a result of geographical speciation. Consider species called allopathic. In order to explain the fact of their appearance, use data in geology and paleogeography. Individuals of such communities compete with each other quite strongly, since they require the same food resources. It is this feature that characterizes interspecific competition.
Examples of animals subjected to geographic speciation are North American beavers and minks. Several hundred thousand years ago, Asia and North America were connected by land.
Aboriginal species of rodents lived on the mainland. When the Bering Strait appeared, the Eurasian and American populations of these animals as a result of divergence formed new species competing with each other. Differences between individuals of populations are amplified as a result of the shift of characters.
Is it possible to reduce interspecific competition?
Let us once again clarify that in demecology interspecific competition is the relationship of organisms belonging to populations of various species and requiring similar resources necessary for their vital functions. This may be the biotope space, light, moisture, and, of course, food.
In vivo, communities of different taxa using a common range and forage can reduce the pressure of competition in various ways. How is interspecific competition reduced? An example is the division of the range, leading to different types of food for waterfowl - the cormorant and the long-nosed cormorant. Although they live on a common territory, individuals of the first species feed on benthic invertebrates and fish, and the second, they feed in the upper layers of the water.
Autotrophic organisms are also characterized by interspecific competition. Examples of plants that confirm the mitigation of the struggle for existence are herbaceous species and tree-like forms. These populations have a multi-level root system, which ensures the separation of soil strata from which plants absorb water and minerals. The plants that form the forest litter (anemone, buttercup, sour, bearberry) have a stem root length of several millimeters to 10 centimeters, and perennial woody gymnosperms and flowering plants from 1.2 m to 3.5 m.
Interference competition
This form occurs if different species use the same environmental factor or resource. Most often, this is a common feed base. In insects, as in plants and animals, interspecific competition is also widespread.
Examples, photos and a description of the experiment, below, explain the study of R. Park, carried out in laboratory conditions. In the experiments, the scientist used two types of insects belonging to the family of dark beetles - the methors (flour mealworms).
Individuals of these species competed among themselves for food (flour) and were predators (they ate Khrushchaks of another species).
Under artificial conditions of the experiment, abiotic factors changed : temperature and humidity. With them, the probability of dominance of communities of one kind or another changed. After a certain time interval, only one species was found in the artificial medium (a box with flour), and the other completely disappeared.
Operational competition
It arises as a result of a deliberate struggle of organisms of various species for the abiotic factor, which is at a minimum: food, territory. An example of such a form of ecological interaction is the feeding of birds belonging to different species on the same tree, but in its different tiers.
Thus, interspecific competition is a type of interaction between organisms in biology that leads to:
- to radically dividing populations of various species into diverging ecological niches;
- to expel one less plastic species from biogeocinosis;
- to the complete ellimination of individuals of a competing taxon population.
Ecological niche and its limitations associated with interspecific competition
Ecological studies have established that biogeocinoses consist of as many ecological niches as many species live in the ecosystem. The closer the ecological niches of communities of important taxa in the biotope are spatially closer, the fiercer their struggle for better environmental conditions:
- territory;
- feed base;
- population residence time.
These are the three main parameters of a real populated ecological niche. It fixes the limitations of the way the population exists, such as parasitism, competition, predation, narrowing of the range, and a decrease in forage resources.
The decrease in environmental pressure in the biotope occurs as follows:
- layering in a mixed forest;
- various habitats of larvae and adults. So, in dragonflies, mollusks live on aquatic plants, and adults mastered the air environment; in the May bug, the larvae live in the upper layers of the soil, and adult insects live in the above-ground airspace.
All these phenomena characterize such a concept as interspecific competition. The examples of animals and plants given above confirm this.
Interspecific Competition Results
We consider a widespread phenomenon in wildlife, characterized as interspecific competition. Examples - biology and ecology (as its section) - present to us this process both in the environment of organisms belonging to the kingdoms of mushrooms and plants, and in the kingdom of animals.
The results of interspecific competition include the coexistence and replacement of species, as well as ecological differentiation. The first phenomenon is stretched in time, and related species in the ecosystem do not increase their numbers, since there is a specific factor affecting the reproduction of the population. Substitution of species, based on the laws of competitive exclusion, is an extreme form of pressure of a more plastic and certified species, which inevitably entails the death of an individual - competitor.
Environmental differentiation (divergence) leads to the formation of little-changing, highly specialized species. They are adapted to those areas of the general range where they have advantages (in terms and forms of reproduction, nutrition).
In the process of differentiation, both competing species reduce their hereditary variability and tend to a more conservative gene pool. This is explained by the fact that in such communities the stabilizing form of natural selection will dominate its moving and disruptive species.