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Neutral Theory Of Natural Selection Report

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Background
The theories of evolution-selection and neutral—explain the mechanism by which evolution come about. These theories disagree on the proportions of the kinds of mutations/changes (advantageous, deleterious and neutral) that contribute to evolution. In addition the theories disagree on the fact that either the trait (allele) established in the population are a function of random chance events or is a function of carefully selected non-random adaptive process. Natural selection favours the latter, while neutralists favour the former.

The selection theory
The natural selection theory postulate that most mutation/changes that lead to evolution are deleterious, a few are neutral and very few are advantageous. The mutations are essential …show more content…

Hence, random genetic drift is, by far, the dominant mechanism molecular of evolution and explains the variation within and between species. For example, if a population carries several different alleles of a particular gene, chances are that each of those alleles is equally good at performing its job. Hence none of the alleles can be said to be more fit than the other. Allele frequencies in small populations do not generally reflect those of larger populations since too small of a set of individuals cannot represent all of the alleles for the entire population. Genetic drift occurs when the population size is limited and therefore by chance, certain alleles increase or decrease in frequency. Unlike natural selection, genetic drift is random and rarely produces adaptations to the environment. It is important to note however that the neutral theory does not suggest that: organisms are not adapted to their environments; all morphological variation is neutral; all genetic variation is neutral and that natural selection is unimportant in shaping genomes. It in facts believes that natural selection helps to rapidly purge the genome of deleterious …show more content…

It is a non-random process
Changes which are established in the population are not necessarily adaptive. They are a function of chance Changes are directed towards heritable adaptations which are best fitted for the current environment
Genetic drift acts upon the genotypic frequencies within a population without regard to their phenotypic effects—silent or neutral mutations which do not reflect any observable phenotypic change Favours the spread of alleles whose phenotypic effects increase survival and/or reproduction of their carriers, lowers the frequencies of alleles that cause unfavourable traits, and ignores those that are neutral
Summarily focuses on the evolutionary changes occurring at the molecular level Places more emphasis on the evolution of physical traits or

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