The Four Forces Of Evolution And Natural Selection

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The four forces of evolution are mutation, gene flow, genetic drift, and natural selection. Mutation is a random change in a gene or chromosome, resulting in deletions, additions, or substitutions in the DNA sequence. Without mutation, there would be no evolution because the only way a sex cell can be passed down is through mutation. Gene flow is the exchange of genetic material between two populations. Genetic drift is the random change in allele frequency from one generation to the next. Finally, natural selection is concept in which some organisms have a greater chance of surviving and reproducing than others due to features that are better adapted to the environment. (http://www.wwnorton.com/college/anthro/our-origins2/ch/04/answers.aspx). Natural selection is the greatest tangible example of evolution in history. In history we have seen animal and humans adapt and only the best adapted organisms will survive. This concept can be supported by Darwin's theory of "survival of the fittest". …show more content…
Sickle-cell anemia is a specific form of anemia caused by a mutated hemoglobin allele that distorts the red blood cells into a crescent shape at low oxygen levels. Balanced polymorphism is where two different versions of a gene are maintained in a population because it helps the organisms survive better. Sickle- Cell anemia is an excellent example of balanced polymorphism because people with both types of b-globin sickle-cell alleles develop red blood cells that resist the cause of malaria. People with two copies of the B-globin sickle cell allele will end up developing sickle-cell disease and will have a shorter life span. In this case mutation helps the organism survive, hence, a great example of balanced