Essay On Evolution

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Essay on Evolution

     There are many mechanisms that lead to evolutionary change. One of the most important mechanism in evolution is natural selection which is the differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment. Natural selection occurs when a environment makes a individual adapt to that certain environment by variations that arise by mutation and genetic recombination. Also it favors certain traits in a individual than other traits so that these favored traits will be presented in the next generation. Another mechanism of evolution is genetic drift. Genetic drift is a random change in a small gene pool due to sampling errors
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     Not only are there mechanisms of evolution, but there is also evidence to prove that these mechanisms are valid and have helped create the genetic variety of species that exists today. Antibiotic resistance in bacteria is one example of evolutionary evidence. In the 1950's, Japanese physicians realized that a antibiotic given to patients who had a infection that caused severe diarrhea was not responding. Many years later, scientists found out that a certain strain of bacteria called Shigella contained the specific gene that conferred antibiotic resistance. Some bacteria had genes that coded for enzymes that specifically destroyed certain antibiotics such as ampicillin. From this incident, scientists were able to deduce that natural selection helped the bacteria to inherit the genes for antibiotic resistance.
     Scientists have also been able to use biochemistry as a source of evidence. The comparison of genes of two species is the most direct measure of common inheritance from shared ancestors. Using DNA-DNA hybridization, whole genomes can be compared by measuring the extent of hydrogen bonding between single-stranded DNA obtained from two sources. The similarity of the two genes can be seen by how tightly the DNA of one specie bonds to the DNA of the other specie. Many taxonomic debates have been answered using this method such as

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