Nei Masatoshi
Institute of Molecular Evolutionary Genetics and Department of Biology, Pennsylvania State University, 328 Mueller Laboratory, University Park, PA 16802, USA.
Proc Natl Acad Sci U S A. 2007 Jul 24;104(30):12235-42. doi: 10.1073/pnas.0703349104. Epub 2007 Jul 17.
Recent studies of developmental biology have shown that the genes controlling phenotypic characters expressed in the early stage of development are highly conserved and that recent evolutionary changes have occurred primarily in the characters expressed in later stages of development. Even the genes controlling the latter characters are generally conserved, but there is a large component of neutral or nearly neutral genetic variation within and between closely related species. Phenotypic evolution occurs primarily by mutation of genes that interact with one another in the developmental process. The enormous amount of phenotypic diversity among different phyla or classes of organisms is a product of accumulation of novel mutations and their conservation that have facilitated adaptation to different environments. Novel mutations may be incorporated into the genome by natural selection (elimination of preexisting genotypes) or by random processes such as genetic and genomic drift. However, once the mutations are incorporated into the genome, they may generate developmental constraints that will affect the future direction of phenotypic evolution. It appears that the driving force of phenotypic evolution is mutation, and natural selection is of secondary importance.
近期发育生物学研究表明，控制发育早期所表达表型特征的基因高度保守，且近期的进化变化主要发生在发育后期所表达的特征上。即便控制后者特征的基因通常也是保守的，但在亲缘关系相近的物种内部和之间存在大量中性或近乎中性的遗传变异。表型进化主要通过在发育过程中相互作用的基因发生突变而产生。不同门或纲的生物体之间存在的大量表型多样性是新突变积累及其保守性的产物，这些新突变和保守性促进了对不同环境的适应。新突变可能通过自然选择（消除已有的基因型）或通过诸如遗传和基因组漂变等随机过程被纳入基因组。然而，一旦突变被纳入基因组，它们可能会产生发育限制，从而影响表型进化的未来方向。看来表型进化的驱动力是突变，而自然选择的重要性次之。
