Neo-Darwinism combines scientific knowledge, especially in genetics, with the evolutionary theory proposed by Charles Darwin.
According to Darwin, all organisms descend as modifications from common ancestors and natural selection works to favor the advantageous traits. Although his theory explains the processes that lead to the modification of species over time, the lack of more in-depth knowledge about heredity and variability made the theory present some unexplained points.
With the advancement of scientific knowledge, these gaps could be explained. Some of the knowledge added to Darwin’s theory with neo-Darwinism are the concepts of mutation and recombination.
Summary on neo-Darwinism
- Darwin proposed an evolutionary theory that was based on two central ideas: common ancestry and natural selection.
- Many areas of scientific knowledge, such as genetics, were still rudimentary when Darwin proposed his theory.
- The synthetic theory of evolution or neo-Darwinism added new scientific discoveries, especially genetic ones, to Darwinism.
- Neo-Darwinism considers that, in addition to natural selection, populations are influenced by other evolutionary factors.
- Mutation and genetic recombination make genetic variability possible.
What is Darwinism?
To understand what neo-Darwinism is, we must first understand the main aspects of the theory of evolution proposed by Darwin, also known as Darwinism. Darwinism is based on two main points: common ancestry and the mechanism of natural selection .
According to Darwin, all organisms descend, as modifications, from common ancestors. This idea goes against the idea that species arose on the planet as they are observed today, that is, they are not immutable. Still according to Darwin, the organisms of a certain species present some variations, in which natural selection acts.
Those individuals who have more advantageous characteristics are more likely to survive and reproduce, passing these characteristics on to their descendants. Natural selection therefore selects the fittest organisms. Over time, these advantageous characteristics accumulate in the population, eventually leading to the emergence of a new species.
For the process of natural selection to occur, it is essential that the individuals of a population show variations among themselves. In addition, the fittest organisms must still transmit these traits to their descendants. Darwin, however, was unable to explain how traits are transmitted between generations and how variability arises between individuals .
What is neo-Darwinism?
Neo-Darwinism or synthetic theory of evolution is an evolutionary theory that is based on the theory of evolution proposed by Darwin, but adds scientific knowledge that made it possible to explain some gaps presented in Darwinism, for example, how variability arises within a population . Neo-Darwinism would therefore be basically a reformulation of Darwin’s theory, incorporating, for example, data on genetics
In neo-Darwinism, in addition to natural selection, other evolutionary factors are considered to act on species, such as mutation, recombination, migration and genetic drift. Mutations and recombination tend to increase genetic variation between individuals, and natural selection works by selecting the variations that guarantee the greatest chance of survival for the organism.
- Mutation : is a change in genetic material that occurs randomly and suddenly in individuals. It is characterized by being the primary source of genetic variability for the species. Mutations occur spontaneously, but can be caused by the action of mutagens. It is worth noting that mutations do not occur as a way of adapting the individual to the environment in which he lives. Some mutations can lead to the development of unfavorable traits, which, in this case, are eliminated. Positive mutations will, through natural selection, be maintained in the population.
- Genetic recombination: As well as mutation, it also increases variability. However, in recombination, we have a rearrangement of genes already existing in a population; already in the mutation, new alleles are formed. Genetic recombination is present in crossing- over (exchange of genetic material between non-sister chromatids) , which occurs in prophase I of meiosis , and in gamete fusion (fertilization).
- Genetic drift : is a change in allele frequencies from one generation to another that occurs due to random events as a result of chance. The genes passed on to the next generations, in this case, are not those that confer greater adaptive success, but those that were “lucky”. Genetic drift, therefore, does not act to produce adaptations. The bottleneck effect and the founder effect are two cases of genetic drift. The bottleneck effect occurs when environmental factors lead to a sudden reduction in population size, and the founder effect occurs when a small population colonizes a new area. Genetic drift, unlike the other factors studied, acts by decreasing genetic variability.