The theory of neutral evolution
This theory is concerned with study of the evolution of selectively neutral traits, i.e., for example, a large part of changes in the DNA sequence. As, in some cases, up to six various triplets of nucleotides code the same amino acid, a change in the DNA need not have any effect on the amino acid sequence of the protein that is coded by this DNA. Thus, mutations that do not affect the sequence of proteins can be invisible for selection and thus their spreading and accumulation in the genome must occur through some other process than selection. Traditionally, primarily genetic drift is considered; however newer discussions consider genetic hitchhiking (which may be more significant). Neutral evolution may be responsible for the evolution of a greater number of traits than selection alone (however, this is not entirely certain6) and can thus substantially contribute to the diversification of species and possibly also to speciation (the splitting off of new species). However, the most interesting class of traits – adaptive traits – cannot be created by the processes of neutral evolution.
- more or less431
- not at all609