Genetic variation

Human Genetic variation
Genetic variation refers to the genetic diversity that exists within a species. This variation result to a difference in the genetic characteristics that are observed within members of a species. Genetic variation in human beings has been observed both at the individual as well as at the group level. Human genetic variation represents the total quantity of hereditary individuality experiential within the human species. This variation allows elasticity and continued existence of a populace in the wake of irregular environmental conditions. Thus, genetic variation is often viewed as a benefit, as it is a form of preparation for the unanticipated (Robert  Joan, 2008).

Mutations are changes in the DNA sequence of a cell. This can be caused by radiation, viruses, transposons and mutagenic chemicals, or errors that occur during meiosis or DNA replication (Cook, 2000). Mutations are the vital basis of genetic variation as they adjust the order of bases in the nucleotides of DNA. The causes of mutation include molecular decay and the other being induced following the interference of external factors such as the ones mentioned above. Mutations are likely to be unusual and a good number of mutations are perhaps harmful. In some cases the new alleles can be favored by nature thus assuring their survival. Natural assortment may bestow an adaptive gain to individuals in a precise environment if an allele provides an aggressive gain. Alleles in assortment are probable to occur only in those geographic regions where they bestow a benefit. Mutation can cause errors in protein sequence thus causing them to function poorly. This can result to a medical condition. This condition caused by mutations is called genetic disorder. Generally, more recent impartial polymorphisms caused by mutation are likely to be moderately geographically restricted and uncommon. On the other hand, older polymorphisms are likely to be common in a wider array of human groups (Drake  Holland, 2001).

When interbreeding happens, non-random mating can at times occur as one organism happens to mate with another based on definite qualities. In this case, individuals in the populace make precise behavioral choices that eventually shape the genetic combinations that emerge in consecutive generations. With such happenings, the mating patterns of that population are no longer random. Nonrandom mating occurs in two forms resulting in dissimilar consequences. One form is inbreeding. This occurs when persons with identical genotypes are likely to mate with one another rather than with persons of different genotypes. The other form of nonrandom mating is outbreeding. With this, an individual with a particular genotype mates with another of a different genotype. Inbreeding can lead to a reduction in genetic variation but outbreeding can lead to an increase. Mating enhances genetic variation by recombination of chromosomes. The recombination that occurs during mating results in the production of a new combination of alleles (Ellis et al, 2001).

Random fluctuations
Random fluctuations in the records of alleles in a population can at times vary. These variations in virtual allele frequency can moreover increase or decrease by chance over time. This is what is called genetic drift. It normally occurs in small populations in which infrequently-occurring alleles face high chances of getting lost. Once it begins, it continues until the concerned allele is either lost by a population or is the only allele present at an exacting gene locus in a population. Both possibilities reduce the genetic variation of a population. It is common when a significant figure of persons in a population die or are or else forbidden from breeding, ensuing in a radical decrease in the mass of the population. Genetic drift causes the new population to be genetically distinct from its previous population leading to the suggestion that it plays a role in genetic variation (Ellis et al, 2001).

A species with a large distribution seldom has identical genetic structure in its entire array. Distribution facilitation of genetic variation can be seen in large populations distributed over a wide physical range with the genetic structure of individuals in the different parts varying. This is as a result of different forces that end up shifting relative allele frequencies in different ways at either end. Individuals affected by this can mate resulting to genetic intermixing that can contribute to more genetic variation at the end. In such a case genetic variation can be curbed by widening the range to stop interbreeding (Drake  Holland, 2001).

Migration refers to the movement of beings from one locality to another. This can occur in cyclical patterns which does not have a great effect as regards the topic of discussion.  When the migrating persons stay and mate with the destination persons, they can offer an unexpected flood of alleles. During mating between the migrating and destination persons, the migrating persons contribute gametes containing alleles that can change the presented proportion of alleles in the destination population. Majority of practical genetic variation takes effect within a population in a given geographic region and not in people in different regions. However, it is possible to exactly recognize the geographic origins of any individuals ancestors by genetic means (Drake  Holland, 2001).

Genetic variation continues to spread as human beings proceed with their day to day life. This is largely influenced by the changing conditions that force generation to genetically change so as to survive. Also mans activities play a role in genetic variation as he seeks to enhance his living. This is largely brought about by his advancement in science and technology.


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