What bothers people? Leave and save individuals with certain indicators and remove the rest, which are less adapted for survival in our harsh world. This process is called artificial selection ; a very important role is played by a person. But our today's task is to get acquainted with natural selection, or rather, we will learn what is interspecific struggle.
Signs that are useful to humans are not always needed and important for animals. Nature is also able to preserve some species, and some to eliminate. This process is called the term "natural selection", and interspecific struggle is one of the tools of this process. That is, animals compete with each other for food, water, territory and so on. So the evolution of species occurs, they are forced to adapt to some factors or simply disappear from the face of the Earth.
C. Darwin
For the first time we heard the term “interspecific struggle” from the great scientist Charles Darwin. It is important to note what he understood by the words spoken. C. Darwin spoke of the struggle for existence in a broad and metaphorical sense. Of course, many species of animals and plants are directly dependent on each other, but during times of famine, living things begin to struggle for resources that allow them to survive and reproduce offspring. Interspecific struggle occurs between individuals of different species (for example, zebra and lion, pigeon and sparrow). In the first example, a lion can eat a zebra to satisfy its hunger, in the second example we presented two species of birds that fight for food and territory.
You can give examples from the underwater world, as some species of fish are fighting for food and territory. The most important factor for victory is the reproduction of offspring. Those fish that lay more eggs will sooner or later displace the other.
Competition
Interspecific struggle for existence is divided into two groups:
- Competition.
- Direct fight.
The first form is the leading one, it is here that the contradictions between living beings appear, which favorably affects evolution. Interspecific struggle, the reasons for which can be divided into competition for biological needs and the same way to satisfy them, is also divided into:
- Trophic competition.
- Topical.
- Reproductive.
The first kind appears if organisms fight for food, solar heat, nutrients and moisture. For example, predators that hunt in the same territory, competing among themselves, evolve. Their sense of smell and vision are exacerbating, their running speed is increasing.
The second type appears between organisms if they live in the same environment and are exposed to the same abiotic factors. This species is the main reason for developing devices for survival in poor conditions.
Reproductive interspecific struggle is common in plants. Those objects that attract color and smell have a great chance for pollination by insects.
Direct fight
If during competition, organisms enter into a confrontation indirectly, that is, with the help of biotic or abiotic factors, then a direct struggle is distinguished by a direct clash of individuals. The following types are distinguished here:
- The fight against biotic factors.
- The fight against abiotic factors.
The first type involves the struggle for food and the possibility of reproduction, that is, it is also divided into trophic and reproductive. In the first case, we are talking about the relationship between plants and herbivores, predators and prey, and so on. This species is more common in interspecific struggle, in intraspecific it is expressed as cannibalism. As a result, plants begin to defend themselves with the help of thorns, poisonous glands and similar means. Animals also develop protective mechanisms (fast running, sharpened sense of smell and vision, maintaining a hidden lifestyle ...), and if we talk about the fight against microbes, immunity is developed.
The second species can be observed in birds, when they enter into an open confrontation between themselves for the ability to breed in this area and get food for their offspring.
Sometimes it’s not so easy to define competition or direct struggle. The line between the two concepts is really very hard to draw. There is one main difference: in competition, organisms fight indirectly, and in a direct fight, they fight among themselves.
Correction in the theory of C. Darwin
We examined the types of interspecific struggle, which are part of the overall struggle for existence. It is important to note that C. Darwin presented this process to us as a result of the contradiction between the desire for unlimited reproduction and limited resources. But scientists who later studied the theory made a correction: the struggle was caused not only by limited territory or lack of food, but also by excessive aggressiveness of predators.