Question

differentiate between gene flow and genetic drift

Answer 1

Genetic Drift

Genetic drift is a mechanism of evolution of biological species that takes place because of the change in the frequency of alleles in a population. These changes in the allele frequency in a population occur randomly. In order to clarify the phenomenon of genetic drift, the understanding about reproduction would be important.

In reproduction, gametes are formed, and gamete formation follows meiosis where one of the two alleles for each trait is separated. When this separation takes place, the number of alleles that could be passed into the next generation takes the nature of a probability value. Therefore, only some alleles are passed into the next generation, and that causes a difference between the two generations in the allele frequency for a particular trait.

One very common example to describe the genetic drift would be that most of the human families have different number of boys and girls, as the X or Y alleles have been passed differently into the new generation from the parents. Although the X and Y alleles do not really contribute for the evolution, the frequency changes in other alleles would have a considerable effect for evolution. It is important to know that genetic drifts are prominent in small populations while large populations rarely have a considerable effect from the phenomenon.

The result of the genetic drift may be a new organism, species, subspecies, or a new type. That result may or may not survive in the environment, because it was not formed through natural selection. Genetic drift is an event that occurs at a chance, and the survival of the new form is also a chance.
Gene Flow

Gene flow is a process of evolution that takes place when genes or alleles move from one population to another. It is also known as the Gene Migration, and that could cause changes in the allele frequency as well as some variations in the gene pool of both populations. When one or a set of individuals from a particular population moves into a new location, either through immigration in the case of animals or carried away by wind in the case of plants, the gene pool of the new location increases. The traits from the immigrants might have an effect to cause some significant changes in the offspring of next generation.

Oceans, mountain ranges, deserts, and artificial walls act as barriers against the gene flow. In addition, some of the differences in sexual preferences could also act against the gene flow. There are some good examples to support this phenomenon from humans regarding a developed immunity for malaria among new Western Africans after their parents mated with Europeans who initially had the immunity. It is interesting to notice that gene flow could take place between two species, as well.