The Causes of Variation & Its Biological Importance

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Variation is the differences that exist between one individual to another. There are two types of variation and they are; interspecific and intraspecific variation. Interspecific is used to describe the variation that occurs between different species (i.e. variations between mice and elephants). Intraspecific variation, on the other hand, is the differences that occur within a species (i.e. hair/eye colour in humans). Individual may look similar to each other and including identical twins, there are no two individuals that are the same. Therefore it is caused by either an individual’s genetics or the environment. It can also be a combination of the two (“Genetics + Environment = Variation”, this can also be referred to as “Genotype + Environment = Phenotype”, this is because phenotype which is the visible characteristics of an individual can be affected due to changes in the environment (i.e. climate). In terms of genetics, variation is brought about through sexual reproduction (i.e. the assortment of the parental chromosomes and random fertilisation of the egg and also through Meiosis where crossing-over of the chromosomes can occur during Prophase I. Genetic variation is therefore something that is inherited. Much of the DNA in an individual is not used so therefore most of the mutations that take place will not show much, if any, effect. However there is the small possibility that mutations can affect important areas of DNA. The rate at which mutations occur can increase as a result of things such as; high energy radiation, x-rays, ultraviolet, tobacco tar etc. The deletion of a base during protein synthesis is where a single base is removed (deleted), as a result, it will have an effect on the rest of the amino acids in the protein, which is more than likely to have a severe effect. Another possibility is base substitution. This is where a base in the
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