During the last ten years, spectacular progress has occurred in the study of molecular evolution and variation mainly because of the introduction of new biochemical techniques such as gene cloning, DNA sequencing, and restriction enzyme methods. Studies at the DNA level have led to many intriguing discoveries about the evolutionary change of genes and populations. These discoveries have in turn generated several new evolutionary theories. Furthermore, the molecular approach is now being used for studying the evolution of morphological, physiological, and behavioral characters. The purpose of this book is to summarize and review recent developments in this area of study. Previously, molecular evolution and population genetics were studied as separate scientific disciplines. In this book, an attempt will be made to unify these two disciplines into one which may be called molecular evolutionary genetics. White emphasis is placed on the theoretical framework, experimental data will also be discussed to present a comprehensive view of the subject. There are highly developed mathematical theories related to the study of molecular evolution and variation. To make the book accessible to a wide audience, however, only those theories that are useful for interpretation and analysis of data are presented. When a sophisticated theory is needed, the meaning of the theory is discussed without going into detail. On the other hand, some detailed explanations will be given of statistical methods that are useful for data analysis. Molecular evolutionary genetics is an interdisciplinary science dependent upon knowledge from many different areas of biology. Particularly important are the evolutionary history of life and the basic structure of genes and their mutations. Therefore, two chapters are devoted to a brief discussion of these subjects. The discussion is based on recent studies, and I hope it is useful even for professional workers. Although the purpose of this book is to discuss the recent development of molecular evolutionary genetics, it is important to know its implications for the general theory of evolution. The final chapter is therefore devoted to a discussion of this problem. The subjects chosen and the views presented in this chapter are quite personal, but they will give some general idea about the relationship between the current study of molecular evolution and the classical study of morphological evolution.
