EVOLUTION

What is evolution?

The combination of changes in the phenotypic and genetic traits in a population through multiple generations. All the biodiversity known until today has evolved from the last universal common ancestor that lived 3.8 billion years ago.

The Evolutionary Theory

The modern evolution theory was developed by Charles Darwin. However, the idea that all living things are related was already proposed in times of the ancient Greeks.

Darwin published “On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life” in 1859 in which he explained the diversity of life based on the idea that all living organisms descend from a common ancestor. Natural selection can be defined as the evolutionary mechanism by which individuals that are better adapted to their environment survive and reproduce more successfully. Evolution by natural selection is one of the most accepted theories in the history of science, supported by paleontological, geological, genetic and developmental evidence. For natural selection to work, individuals need to have phenotypic hereditary variations that influence their fitness (ability to survive and reproduce).

It is important to understand that the heritable variations are caused by random mutations that might be or not be beneficial and that natural selection favors the traits that are more adapted or beneficial in an specific environment. Also, that natural selection is not the same as adaptation, it is a mechanism for evolution.

Mechanisms of evolution

There are many mechanisms that allow evolution to happen: natural selection, the genetic drift, gene flow and mutation bias. As explained before, natural selection is based on phenotypic variation, differential fitness and the heritability of fitness. The genetic drift is the process by which deviations in expected allele frequencies develop in finite populations over time from one generation to the next bu chance. The gene flow or migration is any movement of genetic material from one population to another, it is very important when the an allele is introduced into a population that did not have it previously. Mutation bias is the process of preferential formation of certain types of mutations in certain positions in the nucleotide strand. These type of mutations occur more often than expected under uniformity.