↣ Natural selection

Darwin, in addition to proposing that organisms evolved, also offered a mechanism for such evolution, natural selection. This theory explained how populations could evolve. That is, how these were adapted to live in their environments over time. For to do this, Darwin relied on several observations:

Hereditary characteristics

Darwin found that traits and many of the characteristics in living things are inherited through genes. Therefore, individuals who inherited the traits advantageous could survive, descend in the next generation and reproduce, given the environmental conditions.

More offspring than can survive

Because advantageous traits are heritable, organisms generate more offspring than their environment can support. Therefore, there is a competition for limited resources in each generation because traits are are becoming more and more common. 

Offspring vary in their heritable traits

Over the course of several generations, the population adapts to its environment, with slightly different features. And many of these characteristics (color, size, form…) are heritable.

Charles Darwin's 1859 book, On the Origin of Species, said that the evolution of living beings is produced through a mechanism called Natural Selection. The Natural selection says that environmental conditions favor or hinder (select) the reproduction of organisms according to their particularities.

That is, the concept of this evolutionary theory assumes that species evolved over time over millions of years of small changes that were favored by highlight its most virtuous characteristics, to the detriment of those that were less appropriate for the environment in which they lived. 

The classical formulation of natural selection establishes that the conditions of an environment favor or hinder, that is, they select the reproduction of living organisms according to their peculiarities. Natural selection was proposed by Darwin as a means to explain biological evolution. 

This approach of Darwinis aligned with the thought that evolutionary change occurs through a gradualism that produces linear and continuously small improvements.

Malthus' work on growth of the population, was the basis that he would have taken for his studies, both Darwin as Wallace. It establishes that this factor (growth of population) tends to be very high, which to the availability of food and space are limited will keep it constant, hence this proposition of the idea of ​​competition. Both scientists agree on this basis plot support their theories by establishing two relevant aspects, assuming that living beings can have clones. the notion of competition established earlier by Malthus and finally the latter idea, is what leads them to establish that these variations can be advantageous or not within the framework of said competition. Then he conquers her the resources necessary for life, will result in a struggle that will determine a natural selection which will favor individuals with advantageous variations and eliminate the less effective ones.