Evolution is a process of diversified development in living thing organisms from their initial forms. These gradual changes are normally from simple to more complex forms. Based on evolutionary theory, all organisms are said to have come from a common ancestor. Evolution is influenced by forces referred to as the four forces of evolution (O’Neil). It is only under these four forces that changes and development in living organisms can occur. This research sets to look into how each of the four sources impact variation within and between populations the isolating mechanisms that create speciation.
The four sources of evolution are; genetic drift, natural selection, gene flow, and mutation. Genetic drift involves changes in the gene occurrences and patterns in a population of living things (O’Neil). This mostly occurs when a small population is separated from a larger population. Genetic drift leads to changes in allele frequencies which may cause changes that are beneficial, neutral, or in an unfortunate circumstance disadvantageous. When a small population is isolated from a larger population, it starts its own population a situation known as the founder effect. In case of a disaster where a large number of the population is wiped out of the population leaving a few members of the population, this is known as the bottleneck effect.
Natural selection involves the random selection of traits that are beneficial to an organism. Those that are not of any helpful use and are harmful are automatically overlooked taking on only those that are beneficial (O’Neil). However, natural selection can preserve or run down the genetic makeup in an organism depending on its action. When a harmful allele is destroyed, then this action destroys the genetic variation. if the genetic makeup is more fit and beneficial to the organism, then through natural selection the genetic variation is maintained.
Gene flow is the transfer of alleles of genes from one group of inhabitants to another. This is also known as gene migration where, unlike genetic drift, it involves the mixing of genetic makeup. The combination of two gene pools reduces the genetic variation between the two populations hence acting against speciation. Mutation on the other hand is not a direct cause of evolution but acts as the basis of evolution (O’Neil). The effects of mutation are changes in the DNA sequence these changes like in genetic drift can either be beneficial or detrimental. Mutation however does not depend on environmental changes whatsoever. it causes variation randomly during cell division then through natural selection the bacteria with the beneficial set of mutations survive.
In this research, a number of reasons for the evolution of organisms are given. In the above forces of evolution (O’Neil), the mutation is the only force that has no response to external or environmental influence. This means that mutation does not respond to the environmental factors as all the other forces do. However, it is the basis for genetic variation in all aspects as it involves the DNA sequence. The four forces of evolution provide un-debatable evidence and viable explanation for the changes in individual organisms. The evolution theory resolves the mystery of these changes and gives clear reasons to believe that some developments must have occurred to organisms for the changes we see to happen in a scientific explanation.
O’Neil, Dennis. Evidence of Evolution. Palomar.edu. 2012. Web.