C. Darwin put three main factors in his explanation of evolutionary mechanisms: the variability of organisms, the struggle for existence, and natural selection, among which natural selection is the guiding, driving force.
Darwin’s theory can be formulated in the form of fairly simple provisions:
Organisms are volatile. It is difficult to find such a property or trait by which individuals belonging to a given species would be completely identical.
Differences between organisms, at least in part, are inherited.
Theoretically, under favorable conditions, any organisms can multiply exponentially and are able to fill the Earth, but this does not happen, since life resources are limited, which leads to a struggle for existence, in which not everyone survives.
As a result of the struggle for existence, natural selection takes place – those individuals survive who have properties that are useful in these conditions. Survivors pass these properties on to their offspring. Therefore, these properties are fixed in a series of subsequent generations.
Individual hereditary deviations (hereditary variability), the struggle for existence and natural selection in a long series of generations provide adaptive changes in organisms to specific conditions of existence. The same processes determine the diversity of species and the general increase in the level of organization of the organisms that inhabit the Earth
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