分子进化中性理论的进展

中性理论与达尔文的自然选择进化论有明显的差别。中性论认为在分子水平上覆盖着多数的进化改变，是在连续产生突变时，由于选择中性（即选择相等），使突变得到随机的固定（即小群体内，样本的随机漂变）。还认为在分子水平上，大多数的种内变异（如蛋白质和ＤＮＡ多态）是选择中性或近于中性，它们能够保持在种内是由于突变的产生和随机消失之间的平衡引起的。近年来，ＤＮＡ顺序的研究资料，都有力地支持中性论，如鼠的拟球蛋白基因、鼹鼠的αＡ－晶状体蛋白、流行性感冒Ａ病毒基因，果蝇的核和线粒体基因等。所以，从地球上生命的历史来看，中性进化的改变至少在数量上已超过达尔文自然选择进化的改变。

ADVANCES IN THE NEUTRAL THEORY OF MOLECULAR EVOLUTION

In sharp contrast to the Darwinian theory of evolution by natural selection.the neutral theory claims that the overwhelming majority of evolutionary changes at the molecular level are caused by random fixation (due to random sampling drift infinite population) of selectively neutral (i.e.,selectively equivalent) mutants under continued inputs of mutations.The theory also asserts that most of the genetic variability withins species at the molecular level (such as protein and DNA polymorphism) are selectively neutral or very nearly neutral and that they are maintained in the species by the balance between mutational input and random extinction. The recent outpouring of DNA sequence data has greatly strengthened the theory. They include such topics as pseudoglobin genes of the mouse, 2A-crystallin genes of the blind mole rat, genes of inluenza A virus vs.mitochondrial genes of fruit flies. In other words, neutral evolutionary changes have predominated over Darwinian evolutionary changes, at least in number, throughout the whole history of life on Earth.