The paper is focused on describing four basic causes of evolution, namely natural selection, mutation, genetic drift, and gene flow. As a matter of fact, all the stated above elements contributed to the process of evolution. The paper examines the contribution of every cause of evolution.
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Natural selection is the process of selection of genotypes of individuals that are most adapted to the conditions of the environment, and the elimination of genotypes of individuals that are less adapted to the conditions. In the process of natural selection, the survival or death of particular animals is not as much important as their selective breeding (OpenStax, 2013). The primary significance in the evolution is not survival of the species but the contribution of each of the species in a population’s gene pool. A great contribution to the gene pool of the population will make the animal that will leave bigger progeny. Animals that do not have progeny are irrelevant to evolution. Only breeding leads to the emergence of evolutionary phenomena.
Natural selection is the only factor in evolution, leading to an increase in fitness. It should be emphasized that not only individual features are selected but the whole genotypes, which are the carriers of these features. Only natural selection can explain the adaptation of organisms to their environment and their striking diversity. The necessary prerequisite for natural selection creates a struggle for existence.
The mutation is the destruction of existing DNA (OpenStax, 2013). The mutation changes the location of the nucleotides that make up the DNA molecule, giving rise to negative consequences. There are no proven cases where the mutation played a positive role in improving any species. It can become a cause of abnormal phenomena. As a result of a mutation, a DNA molecule cannot gain new information (OpenStax, 2013). Thus, mutations are unable to influence the genetic content of cells, and therefore, cannot generate “vertical” evolution. Even in controlling the process of mutation, it is impossible to create new and better creations.
Genetic drift is considered as a factor that plays a crucial role in the evolution of populations. Due to drift frequency alleles may occasionally change in populations until they reach a point of equilibrium, namely the loss of one allele and fixing another. Genes drift independently in different populations (OpenStax, 2013). Therefore, the results of the drift are different in different populations. Thus, genetic drift from the one hand leads to a reduction of the genetic diversity within the population, and on the other hand, it leads to an increase of the differences between populations, to their divergence. This divergence may, in turn, serve as the basis for speciation.
Gene flow is a change in gene frequencies in the gene pool of the population under the influence of migration. The population can get a new allele not as a result of mutation but as a result of migration. The example of gene flow is an animal that travels to a different geographical location and joins another population (OpenStax, 2013).
OpenStax. (2013). Concepts of Biology. Houston, TX: OpenStax College.
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