Natural selection is the main driving force behind the evolution of all living organisms. The existence of this factor was found out by several English researchers: Blythe, Matthew, Wallace, Wells, Darwin. However, only the latter, revealing the significance of this phenomenon, created the theory of natural selection. According to Darwin, the fittest organisms survive, resulting in an evolutionary process based on the indefinite genetic variation in generations.
Natural selection is the preservation of favorable individual changes and differences against the background of the destruction of harmful ones. Thus, according to Darwin, the main driving force of evolution contributes to the improvement of each organic creature in the conditions of its existence.
As a provoking factor, natural selection is endowed with some features. The main ones are: adaptive orientation, accumulating and integrating impact, probabilistic nature.
The probabilistic nature is determined by two sides of the selection process: stochasticity and statisticality.
A quantitative concept (statistical) is used to characterize a structure that has many components that are independent of each other. In living conditions, a population is attributed to such a system. It consists of individual individuals of unequal fitness.
The concept of "stochastic" is used to describe phenomena using probability theory.
Natural selection involves both survival and reproduction of individuals. In other words, an individual more adapted for survival and reproduction has great potential to leave offspring. At the same time, the probabilistic nature manifests itself in the tendency to separate the more fit representatives of the group, but not necessarily the individual that is better than others.
Natural selection is characterized by a cumulative effect. It consists in the gradual addition of small beneficial genetic changes. This leads to an improvement in the signs of adaptation or the emergence of new ones.
Scientists have long been trying to establish a classification of the driving factor of evolution. However, the system is still under development. This is mainly due to the fact that natural selection and its forms are rather difficult to combine into a clear structure. This, in turn, is due to the impossibility of determining a single classification core.
The most logical solution to this problem, according to scientists, is to distinguish between the characteristics of influence and the very nature of selection.
Thus, two main types of the causative factor of evolution are distinguished: stabilizing and driving.
Driving selection acts as a creative force. Its mechanism is based on the preservation of useful deviations from the average indicator of the accepted norm, which are adapted to new environmental conditions, thanks to the emission of representatives of the past norm.
Driving selection is interconnected with stabilizing. Moreover, both of these concepts are two facets of the same process.
The stabilizing factor implies maintaining the norm established in specific conditions when eliminating deviations.
Naturally, natural selection is the most significant, however, not the only evolutionary factor. Mutations also make changes in the gene pool of populations. However, they occur extremely rarely, and therefore do not make a significant contribution to evolution.
Distinguish between natural and reproductive selection. These two phenomena may not coincide with each other. The tasks of the first are to “reject” unfavorable varieties of variability, as well as to influence the nature of the evolution process itself.