Essay On Evolution

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 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...