Demecology is a scientific discipline that considers the diversity of relationships between living organisms that are part of different populations. One form of such interaction is interspecies competition. In this article, we will consider its features, the patterns of the emergence of the struggle for territory, food and other abiotic factors in organisms living in natural and artificial biogeocinoses.
Species and ecological characteristics
During historical development, biological taxa (groups with some commonality) adapt to abiotic and biotic factors of nature. The former include climate, the chemical composition of the soil, water and air, etc., and the latter - the impact of the vital activity of some species on others.
Individuals of the same species settle unevenly in certain areas of biotopes. Their clusters are called populations. Communities of the same species constantlyinteract 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, occurs directly in places where the ranges of communities of different 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 was completely eliminated (extinct) within 20 days.
What causes range overlap
If the habitats of two different species merge in some areas of the biotope, then quite strong differences arise between individuals in the external structure, terms of 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 there is practically no interspecific competition between the populations. The example with finches, observed by Charles 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 above-mentioned scientist G. Gauze formulated an important ecological pattern: if trophic and other needs of populationstwo different species coincide, then such taxa become competing. This excludes their further coexistence in the same area, 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 reservoir. Roach fry are more active and voracious, so they successfully crowd out young perch and rudd.
Sympatric and allopatric taxa
They arose as a result of geographic speciation. Consider the species called allopatric. In order to explain the fact of their appearance, data in geology and paleogeography are used. 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 that have undergone 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 that compete with each other. Differences between individuals of populations are amplified as a result of shifting traits.
Can interspecies competition be reduced?
Let's clarify once again that in de-ecology interspecificcompetition is the relationship of organisms that are part of populations of different species and require similar resources necessary for their livelihoods. It can be biotope space, light, moisture and, of course, food.
Under natural conditions, communities of different taxa sharing a common range and prey base can reduce competitive pressure in a variety of ways. How does interspecies competition decrease? An example is the division of the range, leading to different types of food for waterfowl - the great cormorant and the long-nosed cormorant. Although they live on a common territory, individuals of the population of the first species feed on benthic forms of invertebrates and fish, and of the second species they get food in the upper layers of the water.
Interspecific competition is also characteristic of autotrophic organisms. Examples of plants that demonstrate the mitigation of the manifestations 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 layers from which plants absorb water and minerals. Plants that form the forest floor (anemone ranunculus, oxalis, bearberry) have a taproot length from a few millimeters to 10 centimeters, and perennial tree species of gymnosperms and flowering plants - from 1.2 m to 3.5 m.
Interference competition
This form occurs when different species use the same ecological factor or resource. Most often this is a common food base. In insects, as in plants and animals,interspecies competition is widespread.
Examples, photo and description of the experiment below, explain R. Park's research, carried out in the laboratory. The scientist used in the experiments two types of insects belonging to the family of dark beetles - martyrs (flour beetles).
Individuals of these species competed with each other for food (flour) and were predators (they ate other types of beetles).
In the artificial conditions of the experiment, abiotic factors changed: temperature and humidity. With them, the probability of the dominance of communities of one or the other species changed. After a certain period of time, in the artificial environment (a box of flour), individuals of only one species were found, while the other completely disappeared.
Exploitative competition
It arises as a result of the purposeful struggle of organisms of various species for an abiotic factor that is at a minimum: food, territory. An example of this 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 in biology a kind of interaction between organisms that leads to:
- toward a radical division of populations of different species into mismatched ecological niches;
- to the expulsion of one less plastic species from biogeocinosis;
- to the complete elimanation of individuals in the population of a competing taxon.
Ecological niche and its limitations,associated with interspecific competition
Ecological studies have established that biogeocinoses consist of as many ecological niches as there are species living in an ecosystem. The spatially closer the ecological niches of communities of important taxa in the biotope, the more fierce their struggle for better environmental conditions:
- territory;
- stern base;
- population residence time.
These are the three main parameters of a real populated ecological niche. It fixes the limitations of the mode of existence of the population, such as parasitism, competition, predation, narrowing of the range, reduction of food resources.
Reducing the pressure of the environment in the biotope occurs as follows:
- tiering in mixed forest;
- various habitats for larvae and adults. So, in dragonflies, naiads live on aquatic plants, and adults have mastered the air environment; in the May beetle, the larvae live in the upper layers of the soil, and adult insects live in the ground-air space.
All these phenomena characterize such a concept as interspecific competition. The animal and plant examples above support this.
Results of interspecies competition
We are considering a widespread phenomenon in wildlife, characterized as interspecific competition. Examples - biology and ecology (as part of it) - show us this process both in the environment of organisms belonging to the kingdoms of fungi and plants, and in the animal kingdom.
The results of interspecific competition include the coexistence and substitution of species, as well as ecological differentiation. The first phenomenon is extended in time, and related species in the ecosystem do not increase their numbers, since there is a specific factor that affects 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 sertile species, which inevitably entails the death of an individual - a competitor.
Ecological differentiation (divergence) leads to the formation of little changing, highly specialized species. They are adapted to those areas of the common 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 because in such communities, the stabilizing form of natural selection will dominate over the driving and disruptive types.
