Essay by James WonHigh School, 12th gradeA+, February 1997

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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 in propagation of

alleles or chance. Genetic drift depends greatly on the size of the gene pool. If

the gene pool is large, the better it will represent the gene pool of the previous

generation. If it is small, its gene pool may not be accurately represented in the

next generation due to sampling error. Genetic drift usually occurs in small

populations that contain less than 100 individuals, but in large populations drift

may have no significant effect on the population. Another mechanism is gene

flow which is when a population may gain or lose alleles by the migration of

fertile individuals between populations. This may cause the allele frequencies in

a gene pool to change and allow the organism to evolve. The most obvious

mechanism would have to be mutation that arises in the gene pool of a

population or individual. It is also the original source of the genetic variation that

serves as raw material for natural selection.

Not only are there mechanisms of evolution, but there is also evidence to

prove that these mechanisms are valid and have helped create the...