適応進化のメカニズムに関する分子集団遺伝学的研究

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The development of the neutral theory in molecular evolution established that the majority of nucleotide substitutions occurred during the course of evolution are caused by random fixation of neutral mutations. On the other hand, we can see tremendous amount of diversity of organisms at the phenotypic level, many of which has been explained in terms of Darwinian adaptive evolution. Some of newly emerging molecular data are contradictory to the strict neutral mutation theory as well. The present study was carried out with an idea that adaptation was achieved by a relatively small number of changes such as gene duplication followed by functional diversity, amino-acid-alternating substitutions, and changes in regulatory regions. We successfully detected the effects of positive and negative natural selection from DNA sequence data combined with theoretical analysis based on the population genetics.The recent advance of molecular biology has been accumulating diverse biological information such as high-order structure of proteins and gene interaction at very high rate, and also reveals the complication of genetic networks. Further advance of theoretical and experimental population genetics along this line will be needed to get a deep understanding of complicated evolution at the phenotypic and the molecular level.