Although it is difficult for us to imagine, the animals and organisms that inhabit planet earth have not always maintained the same appearance and characteristics that we know today, but have evolved from other species and developed small modifications that have allowed them adapt to its environment and survive. Thus, there are many other species that have become extinct because they have not managed to evolve or adapt to their environment.
Do you want to know more about this process? In Green Ecologist we tell you what is natural selection with examples.
What is natural selection: definition and example
The term natural selection refers to the selection that occurs in nature of those genetic traits or traits that are most suitable and that favor the survival of the species, so that these are transmitted to their offspring in order to ensure the preservation of the species.
A example of natural selection is the transmission of the gene that defines the length of the neck of giraffes. Imagine for a moment that the giraffe comes from a very different ancestor to this species, with a much shorter neck, similar to a horse. This species fed on the leaves of tree branches, so it had to continually stretch its neck to get food, so that species with longer necks would have a better chance of obtaining food than those with shorter neck.
Consequently, with the passage of time, the species with the shorter necks had fewer options of being able to satisfy their nutritional needs and survive, while those with the longer necks continued to feed and reproduce, thus transmitting this genetic characteristic to their offspring, which each time, would present a longer neck. This is the case with all kinds of genetic characters in all species of living beings, giving rise to what we know as biological inheritance of each species.
Types of natural selection
Within this we can find different types. Specifically, different types of natural selection are:
Disruptive selection
This type of natural selection usually results in two different species. Thus, the extinction of neither of the species occurs, but both are capable of subsisting and adapting to the environment. In the previous example, for example, it would imply the survival of both the short-necked and long-necked species.
Directional selection
This other type of selection implies that, with the passage of time, all individuals adopt a new character, while those that are not capable of evolving become extinct. This type of selection corresponds to the example explained above.
Sexual selection
This natural selection takes place in populations of individuals that compete to reproduce, in such a way that, with the passage of time, individuals inherit and adopt the characteristics that allow the subsistence of the species.
Lamarck and Darwin theories
One of the first researchers to ramble on on this theory was Lamarck, who defended that the development of the species are capable of modifying their body physically from the changes produced in the environment, and these changes are transmitted to their offspring. However, this theory has not been approved by the scientific community, since individuals have a series of limitations when it comes to modifying their body and it is not their actions that give rise to these modifications.
Charles Darwin, defended that these modifications are not due to their training or use but rather, they are linked to the demands of the environment, so that the modification of certain characters and their transmission takes place through a slow process that favors certain traits are passed on to the offspring. Darwin published his theory in his book, On the Origin of Species Through Natural Selection, which caused a great impact and controversy in its time. However, over time his theory has not only been accepted by the scientific community but has also been supported and today constitutes the basis of modern evolutionary theories.
Natural selection and artificial selection
The human being, once he has understood the process of natural selection, has been able to imitate and force it, thus giving rise to the artificial selection.
In this type of selection it is the human being the one who selects the characteristics that it considers beneficial and suitable for the species and encourages its offspring, forcing crosses between individuals, either through the traditional reproduction method or the in vitro reproduction method, produced in the laboratory.
Currently, this type of selection is applied to achieve the desired characteristics in domestic animals and plants or in food products, such as transgenic foods.
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