Mutation is an issue of heredity. It is the basis by which evolution may occur. Citing sources in both the Ascent of Man and the more controversial aquatic ape theory in The Descent of Woman each base their thesis on the propensity of the Homo sapiens to evolve through active mutation in order to survive the species. The traits that are based onto the progeny are not necessary dominant in the parent but evolve when nature attests to some debilitating disease or other race threatening occurrences.
In the following paper the role of mutation in evolution will be emphasized on the genetic level.The most obvious place to visibly see the importance of mutation to evolution is the vast myriads of animal species. There are a great number of different subspecies within the context of the original animal such as the 8 subspecies of fox that each have their own adaptations or mutations that allow them to be better suited for their environment (i. e. the large ears of the San Joaquin kit fox allow for heat to escape faster in the desert climate, the Arctic fox whose fur changes to white during the snow months and dark brown the rest of the year for camouflage purposes for both hunting and escaping).The animal species was first discovered to be divergent in Darwin’s Origin of the Species, when Darwin put to paper the abundant role of natural selection in evolution for the survival of the species; natural selection also having a part to play in mutation.
For it is in mutation that evolution can transpire and without the differences in adaptations of each species the word extinct becomes prevalent but with mutation the word extant takes its place.History Mutation has a short history in human scientific study that dates back to roughly 1886. In this year a Dutch botanist named Hugo Marie De Vries discovered a colony of primroses isolated in a valley. Upon closer inspection Vries discovered that some of the primroses were quite different from the others, though they had all haled from the same seedlings. Vries then dug up the flowers and brought them back to be bred separately and together. In 1900 he had evolved genetics to a level that had already been proposed by Mendel.
At roughly the same point in time in two different geographical places German Karl Erich Correns and Austrian Erich Tschermak von Seysenegg were making the same hypothesis. In Vries garden he observed that the primroses were not exact replicas of their parent seed though the flowers were the same offspring. Some characteristics of the flowers skipped generations while others would appear only for one flower generation and vanish into the genetic history of the flower, remaining dormant.Evolution then was proven to not always proceed in small steps but often times, and more likely there were drastic and noticeable changes that were not microscopic in scale but were clearly visible. These visible changes were called by Vries mutations (mutation’s etymology comes from the Latin word for change). (Asimov, 417).
Darwin Darwin’s theory of evolution is a cornerstone in the concept of mutation being the backbone for survival and the foundation for the ever evolving human race, as Asimov states, “Darwin had advanced the theory of evolution by natural selection a century before.He assumed that selection took place because in every generation there were small variations among the offspring of a particular species. How those variations arose, he didn’t know” (533). Thus, the concept of evolution is well cemented in the scientific community and the variations behind natural selection are accounted for through mutation.
Thus, natural selection was made capable for accounting for the degrees of separation between the same species and mutation was the genetic device enlisted to be the active and missing link between evolution and natural selection.Afterwards, evolution juxtaposed with mutation is understood not only through a molecular level but also on the organism level; that is, not only could mutation be witnessed through the small microscopic studies of genetics but could now be visibly seen in an organism through minor changes in their appearance, behavior, etc. Not only is mutation seen in the human species of evolution but it also stands in the genre of lower animal and plant forms and extends the breadth of the chain of life to bacteria and viruses.As the human race and animals evolve to adapt to their environment so do the diseases that threaten their existence. Luria in 1945 and the microbiologist Alfred Day Hershey, “…showed that bacteriophages underwent mutations as well.
It is for this reason that it is so hard to develop immunity to viral diseases like flue and the common cold. Antibodies might be developed against a particular strain of the virus, but then a mutation will produce a new strain against which the old antibodies are not effective” (554).This is proven with the introduction of penicillin and its abundant propensity to kill viruses; however, the medical market uses other, less strong strains of penicillin so that the virus will not mutate beyond its capabilities. Mutation Mutations are sensitive factors in the chemistry or genes of an entity that are created in response to internal and external factors of the natural environment.
As an example of mutation, germ plasm is thought to be an intricate stereochemic systems. These systems are proven to be impressionable to outside and inside stimuli.On occasion, due to their heightened sensitivity, the undergo periodic changes or mutations, These alterations in genetic factors or factor mutations we shall call them have been most thoroughly investigated in the common fruit fly, Drosophila ampelophila, in which Morgan and others have discovered over 150 factor mutations, each of which is inherited in strict conformity with Mendel’s laws, when tested in contrast with its normal mate as it exists in the wild type” (Babcock, The Role of Factor Mutations in Evolution 117-118).Thus, mutation is shown in the evolution of plants; it has yet however been proven to be of consequence to the vital role of evolution. Mutations’ Role in Evolution Mutations are thought to be random occurrences in progeny. The variable genetic make-up produces any combination of latent features passed on from the parents to the child that may or may not be relevant in the general course of life.
Mutations may remain dormant for a period of generations such as a child being born with red hair when neither his/her parents nor grandparents had this trait.In this reasoning is found the cause of mutation as thought of as being a random occurrence; it is without pattern, and seemingly subject to its own whim instead of being a trait designed to adhere to specific needs of the species during a specific time period. Sniegowski and Lenski state of evolution and mutation that, …of evolutionary theory, is that mutation is random with respect to its adaptive consequences for individual organisms: that is, the production or variation precedes and does not cause adaptation.Several recent experimental reports have challenged this tenet by suggesting that bacteria (and yeast) may have mechanisms for choosing which mutations will occur (553).
Thus, as referenced in this excerpt is the relevance of mutation to evolution in the realm choice. Mutation as Choice In the realm of mutation taking initiative in evolution the theory of directed mutation has occurred. This is a very controversial theory but has in its elemental design a way by which evolution is dependent upon mutation.Directed mutation or adaptive mutation has been the cornerstone of the theories involving mutation and evolution.
The idea of natural selective is prevalent in this hypothesis as it presents a seemingly random array of genetics from which the entity chooses according to internal and external stimuli. In the experiments conducted to introduce mutation as a solid backdrop for evolution the use of cells has been heralded. An experiment done by J and E Lederberg, numerous cells were places upon an agar plate.A stripe of velveteen was used in transferring ‘a spatially ordered inoculum of cells from this master plate’ (558).
These cells were then placed upon duplicate plates which each were exposed to an agent. Thus cells were forced to mutate resistance in order to survive. Thus, cells adapted or mutated in order for the population of cells to remain extant. The cells that resisted the agent then gave their replicated cells the same mutation in order for the agent to have little of no effect on the ‘offspring’ of the cell and thus ensuring that mutation is used in evolution to guarantee survival.
As J and E Lederberg state of adaptive mutation and the cell experiment, “(they) observed a striking correspondence in the locations of the resistant colonies on replica plates made from the same master plate, indicating that resistant cells had arisen by spontaneous mutation and increased in number by clonal growth on the master prior to selection” (558). The experiment not only proved the choice of mutation but as the Lederbergs found out, they were also able to produce within the selected plate colonies the same mutation without having to expose them to the agent which externally was used as the impetus for mutation.In a study done at Harvard University by John Cairns et al. suggests that cells know instinctively what mutations will better suit them in survival and thus, they duplicate and grow according to this innate system of mutation, Most biologists now believe- and Cairns has acknowledged-that the seeming excess of beneficial mutations found in many directed-mutations studies might arise because researchers are more likely to spot and so count beneficial events than they are harmful ones.Various theories have been advanced to explain why, although none has gained universal acceptance.
Recent experiments, however, provide important evidence for one effect that could produce such a counting bias. The effect, hypermutation , thus might make true directed mutation unnecessary. But hypermutation itself opens the door to some intriguing possibilities. The concept of hypermutation was conceived by Barry Hall at the University of Rochester.
He conjectured that when cells (bacterial) are starving, they will form multiple mutations.Thus, the experiment dealing with mutation and cells is clearly shown to only focuses on beneficial results in the bacterial cells that remain alive as opposed to the ones that died due to the starvation and whose results were not recorded. Further tests explored whether mutation was a result of starvation or of adaptation to nutritional stress (Genetics, Online). Mutation is further emphasized as having a strong role in evolution on Genetics Online,Hall has recently isolated five bacterial genes that make excess favorable mutations seem to appear elsewhere in the bacterial DNA.
Hall thinks his newly isolated genes somehow stimulate hypermutation and so generate the illusion of overabundant advantageous mutations. " In my gut I feel it’s an evolved phenomenon ," he says. Pure directed mutation , with its spooky foreknowledge, may be dead. But real mechanisms that produce the ghost of directed Mutation could yet shake up biology.Thus, the genes ability to stimulate and have precognition as to what mutation would best benefit it becomes a factor in the concept of mutation and evolution.
Functions of Mutation Neo-Darwinians argue that mutation occurs despite relevant facts of environmental needs and independent of necessity; a mutation is a fluke of nature, a random occurrence but in the above pages this is proven to be false as cells in the experiment responded to outside stimuli and built up an immunity which was inherited by their replicated cells and so on.In experiments done to cells in the area of mutation, the cells undergo exposure to an agent and then they mutate. This has been considered a drawback in adaptive mutation because it is believed that mutations occurred more often in these experiments and so had the natural inclination to adapt to the agent; however it must be noted that the cells selected for the experiments were exposed to stimuli that they would under normal circumstances not have been subject to and as such the mutations that occurred were not a priori but were in fact the cause of the agent.Mutations typically are dependent upon the genotype of a specific entity. Other mutations then pattern themselves after this initial genotype and a new adaptive system is created.
There are however difficulties present in the examination of this initial genotype which includes its disappearance after only a few generations for unspecified reasons.Thus, the reports on cells and mutation are somewhat sporadic in themselves in discovering the importance of mutation to evolution. P. T. Ives states in The Importance of Mutation Rate Genes in Evolution, “…since the gene’s mutagenic properties are so complex and since only by its ability to raise the mutation rate is the gene phenotypically recognizable, it will be a task of considerable difficulty to even roughly its locus. However, since the gene is now successfully balanced with marked chromosomes, the problem of its exact locus is of minor importance” (236).
The mutator gene is responsible for any number of variables in the evolution of an entity.
