Evolution is a very slow process where change in a genetic composition occurs over a long period of time. Micro evolutionary changes which are essential for creation of a new species also happen after a long period of time. These changes are small but observable. (Hariland, Walrath, Prins & McBride ,2010|) Therefore, microevolution refers to the changes within a gene collection that takes place from one generation to another. Frequency of alleles in a given population may change due to the following fundamental factors also referred to as fundamental forces: gene flow, natural selection, generic drift and mutation. It is used as the basic unit of classification in biology and rankings in taxonomy. (Sahney.S. and Benton.M.J. 2008 pg.17-25)
Mutation is the backbone of evolution. It is a change that occurs in DNA that changes the structure of genes randomly. Every cell in the body has DNA. (Dawkins, R.1989 pg 41). It is due to DNA that an organism aspects of life including looks and behavior are. Change in this hereditary material of life in an organism can lead to changes in all its aspects of life. It is through mutation that new alleles and new regulatory regions are created. Mutation can lead to total elimination or survival of a species. Somatic mutation usually takes place in non reproductive cells. Its occurrence will therefore not affect evolution since it would not be passed onto the offspring. (Darwin, c 1959).
Natural selection is the process by which organisms that have specific features that enable them to survive in a struggle for resources manage to be successful. While others who are unsuccessful succumb to what Charles Darwin termed as “the struggle for existence.” Their offspring will have an advantage of existence since they are better adapted to the environment. Isolating mechanisms take its role. Mismatches between mating organisms or incompatibility of gene causes sterility of hybrids. This process has four components: Variation, Inheritance, High rate of population growth and Differential survival and reproduction. (Futyma,D.J.1986 Evolution Biology). Variation shows how different organisms in the same species differ in appearance and behavior. It can be hair color, number of offspring or even the size of the body. Inheritance is where some of the traits are continuously passed on from the parent to the offspring. (Darwin, c 1959 origin of species by natural selection). High population growth rate where most population has more offspring each year than local resources, can lead to a struggle for the available resources. Each generation experiences substantial mortality since the resources are not enough. Differential survival and reproduction is for individuals possessing traits well suited for the struggle for local resources will contribute more offspring to the next generation.(Dawkins, R.1989).
Genetic Drift is also referred to as allelic drift. It is the changes in the frequency of the number of available allele in a population due to random sampling. (Masel J,2011 Generic drift,pg21) It occurs due to a small number of gene pool or a population size. Unlike the natural selection, Genetic Drift depends on statistical chance other than desirable traits. Normally, the number of alleles in a given population becomes smaller with every generation hence through generic drift, an allele can disappear completely from a gene pool. (Fatuyma, Douglas,1998 pg 320)
Gene Flow is the changes in allele frequency as a result of migration eithin a given population. A simple example is pollen being blown from to a different position on other organisms migrating to different locations. These may lead to an addition of new genetic variant to an established gene pool. (Rhymer, Judith, m.1996 pg 71)
Work cited:
Darwin, Charles, and Morse Peckham. The Origin of Species: A Variorum Text. Philadelphia: University of Pennsylvania Press, 1959. Print
Dawkins, Richard. The Selfish Gene. Oxford: Oxford University Press, 1989. Print.
