Mechanisms of Evolution, Essay Example

Certain changes in the gene pool of the population occur due to various factors and lead to the evolution of each population. Mutation, gene flow, genetic drift and natural selection are primary mechanisms and driving forces of evolution of the species.

“In physical terms, a mutation is an alteration in the sequence of nucleotides that comprise DNA – the instructions to make a protein encoded by the mutated DNA are changed.” (Peter Symonds College, 2004) New alleles usually appear as a result of mutation and, therefore, become a source of distinctions among separate animal units of the same species. Though most of DNA changes are harmful and lead to premature death, some of them are crucial for the evolution within the population.

Gene flow (migration) refers to the movement of certain genes within several populations. Gene flow may occur due to various circumstances. For instance, some animals are forced to leave the herd and to join another one. “If genes are carried to a population where those genes previously did not exist, gene flow can be a very important source of genetic variation.” (University of California, 2009)
Genetic drift is another mechanism of evolution, which refers to a change of genetic characteristics of the population over certain period of time. For instance, if the fish is taken out the river and placed to a lake or another environment, it will produce offspring that are distinct from those, which might have appeared in the river. (Bio-Medicine, 2009)

According to Darwin’s natural selection model, only strongest and most adaptable organisms survive. Pictures below show how green beetles are eliminated over time.

On the first stage there is equal amount of green and brown beetles. Due to certain external factors or other natural events, population of green beetles is affected and its quantity is reduced. Therefore, reproduction of green beetles is also affected as their number is much smaller than that of brown insects. As a result brown beetles become dominant and eliminate green ones in a population.

References

Peter Symonds College. (2004). Mutation and Evolution. DNA: Structure and Function. Last retrieved on July 15, 2009 from http://www.makingthemodernworld.org.uk/learning_modules/biology/01.TU.03/?section=7.

University of California. (2009). Gene flow. Last retrieved on July 15, 2009 from http://evolution.berkeley.edu/evosite/evo101/IIIC4Geneflow.shtml.

Bio-Medicine. (2009). Genetic Drift. Last retrieved on July 15, 2009 from http:/ /www.bio-medicine.org/biology-definition/Genetic_drift/.