theory of neutral evolution vs theory of evolution by natural selection

 

The theory of neutral evolution refers to random molecular level evolutionary changes that are caused by mutations of nucleotides. On the other hand, evolution by natural selection implies that individuals with the most advantageous phenotypes, who are better adapted to their environment, will pass their genes on to their offspring.

One main difference is that neutral evolution focuses on a genetic level, the nucleotides of the genome, while the phenotype is what impacts natural selection. These driving forces of natural selection are based on fitness, and the phenotypes that are selected for will be more likely to pass on their genotype. The opposite is true for deleterious genotypes, as their phenotype is not selected for it will removed from the population. The neutral theory does not take into focus the effects of natural selection, just genetic drift. Alleles have the ability to become fixed if they are neutral or advantageous, which is not as prevalent in the theory of evolution by natural selection. These neutral alleles can have very little impact on the phenotype of the individual, but are still a source of evolution.