Evolution Is The Gradual Change Of Genotype And Phenotype Of Organisms

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Evolution is the gradual change of genotype and phenotype of organisms over time in response to selection pressures. This enables organisms to become better equipped to exploit their environment. Random processes are governed by the laws of probability and cannot be forecast except for a certain degree of directionality. Deterministic processes however, are predictable and tend towards a repeated outcome. It is necessary to consider the true role of stochasticity in evolution, first in the frame of intrinsic processes within species such as mutation. Then, exploring how chance governs extrinsic processes which direct the course of evolution such as isolating mechanisms, whilst appreciating the interplay of determinism at certain levels…show more content…
Changes in gene sequence can be brought about by the action of transposable elements. These insert randomly over the entire genome and if this occurs in an exon it can result in an altered gene product. Transposable elements can also stimulate changes in gene expression, by changing the regulatory region a gene is influenced by. The extent to which changes in gene expression can affect evolution is demonstrated by diverse beak morphology in Darwin’s finches. It was discovered that there was a strong link between the expression of Bmp4 and the depth and breadth of the beak. This demonstrates the profound impact that changing expression patterns can have on phenotype, and the significance of the random events that lead to the altered expression in evolution. Gross chromosomal rearrangements such as inversions, translocations and deletions can also result from the action of transposable elements and can alter how groups of genes are inherited by changing linkage groups.
Recombination is the exchange of genetic information between homologous chromosomes. This act remixes existing genetic information into new combinations and is therefore of evolutionary significance. Genes linked by their position to alleles undergoing positive selection, but themselves are not at a selective advantage, are said to be hitchhiking. Recombination alters the genes that are linked and can cause a random gene to spread due to being linked to a selectively advantageous allele. Although randomness
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