Evolution can be understood as a slow process that brings about changes in animals as well as plants as well as its scientific piece. According to the theory of evolution as stated by Charles Darwin, life is assumed to have some sort of relationship. In addition to this, the theory also suggests that there is a possibility of having a common ancestry for most of the organisms. The theory assumes that organism such as birds are related with other organisms. The general genetic mutation which occurs within the organism’s genetic code is responsible for speciation and variation that occurs within the organisms and this brings about different features in the organisms.
According to Darwin’s theory of evolution, species is assumed to be a group of animals or birds that are similar in nature. Each of the member within the species has similar characteristics. For instance, species pet cat is comprised of animals that have sharp teeth, fur, a tail and same number of toes. Population describes all members that belong to same species (Haviland, 2013). During natural selection, species can change and take different forms and ways. This brings about change in the entire population. On the other hand, variation is the differences that results after natural selection where different species have different characteristics after change.

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The four forces of evolution include mutation, genetic drift, gene flow and natural selection. Mutation takes place by chance. This takes place in a chromosome or gene where a physical or behavioral differences occurs in the individuals. Since it affects chromosomes or genes, it is possible to be passed to the next generation. For example, presence of red hair in individuals is an example of gene mutation.

Gene flow is another force of evolution whereby two species or organisms that are geographically separated with each other expressing different genetic make are able to decrease these differences (Haviland, 2013). This involves the exchange of genetic material between such population through meting after they come to one geographical location. The when they met, the genetic variations between the two populations will significantly decrease.

Genetic drift is a random change in the allele frequencies that changes in the small population. This is as a result of random events which occur that are not related to the alleles (Haviland, 2013). This is also random just the same as mutation. This mainly happens in the small population that may have allele drift to fixation, of which, all of the members have that particular allele.

Natural selection on the other hand is a process by which some organisms have a greater chances of surviving as well as reproducing that the others. This is mainly because of presence of features that are well adapted to the environment. Because of this, those organisms that express advantageous features are passed at a higher frequency and thus they are able to be passed to the next generation.

Isolation comes about as a result of physical barrier that occurs within the species. Presence of physical barriers such as mountains and rivers may bring about isolation as it the species may get separated from each other. Such isolations results to changes in the characteristics in that given population (Haviland, 2013). On the other hand, speciation comes as a result of isolation. Different species are isolated and thus they develop different characteristics.
Conclusion

According to evolution, several changes are likely to take place within species of a given population. These changes are purposely for adaptation of these organisms in their environment. The four forces of evolution includes mutation, gene flow, genetic drift and natural selection. These forces are responsible for variations that exists within the species.

    References
  • Haviland, W. A. (2013). The essence of anthropology. Australia: Wadsworth Cengage Learning.