Near neutrality: leading edge of the neutral theory of molecular evolution.

摘要: The nearly-neutral theory represents a development of Kimura’s Neutral Theory Molecular Evolution that makes testable predictions go beyond mere null model. Recent evidence has strongly supported several these predictions, including the prediction slightly deleterious variants will accumulate in species undergone severe bottleneck or cases where recombination is reduced absent. Because bottlenecks often occur speciation and mutations coding regions usually be nonsynonymous, we should expect ratio nonsynonymous to synonymous fixed differences between exceed polymorphisms within species. Numerous data support this prediction, although they have been wrongly interpreted as for positive Darwinian selection. use conceptually flawed tests selection become widespread recent years, seriously harming quest an understanding genome evolution. When properly analyzed, many (probably most) claimed turn out involve fixation by genetic drift bottlenecked populations. Slightly are transient feature evolution long term, but had substantial impact on contemporary species, our own.