Preface

Ever since human beings adopted a diverse way of life on earth, they have continuously attempted to improve on what they found in nature including all kinds of living beings. Once they came to understand that living beings' characteristics are inherited and genetic richness is an advantage against changing environmental conditions, they have developed new strategies to reveal and conserve the genetic diversity in living beings. The main evolutionary mechanisms such as mutation, natural selection, and genetic drift have produced a vast variation of organisms that ended in the formation of many well-defined breeds with different levels of performance. The knowledge of genetic polymorphism and process that underlie the origins and maintenance of the organisms have crucial importance in providing critical insights into the structure and dynamics of living populations. Genetic polymorphism is essential for populations to evolve and cope with environmental changes, new diseases, and pest epidemics. Genetic polymorphisms also provide the opportunity for tracing the history of populations, species, and their ancestors. Therefore, the assessment of genetic variation in species and among populations is important for conservation of genetic resources. Detailed knowledge of genetic variation within and among different breeds is very important for understanding and improving traits of economic importance. Hence, the future improvement is dependent on genetic variation present within breeds and between breed variation.

Over the last few decades there have been dramatic advances in molecular genetics and these developments have provided scientists involved in the conservation and improvement of genetic resources with a range of new techniques for their research. Nowadays techniques are available to determine changes at the DNA level in all kinds of organisms. Differences in gene sequences can be directly observed and described with a degree of precision previously impossible to achieve. Many of the techniques that have been developed have already been used to study the extent and distribution of changes in gene-pool and to investigate evolutionary and taxonomic relationships. With the development of the polymerase chain reaction (PCR) based techniques, in particular, numerous molecular technologies have been, and still are being, developed, which can be used for the detection, characterization, and evaluation of genetic changes in populations. These techniques can be chosen on the basis of how they display genetic differences, the type of data that they produce, the taxonomic levels at which they can be most appropriately applied, and their technical and financial requirements.

The aim of this book is to present the current knowledge of genetic polymorphisms by including the works of some of the scientists engaged in the production of new information used to reveal genetic polymorphisms, often from very different perspectives. Chapters presented in the book demonstrate the future benefit of molecular markers including SNPs in many studies retaining the genetic polymorphisms. In the book, the genetic polymorphism studies that are carried out on different kinds of organisms at the DNA level or gene expression level are particularly important to evaluate the process of genetic polymorphisms.

The purpose of the current book is to provide a glimpse into the dynamic process of genetic polymorphism by presenting valuable research. I would like to express my deepest gratitude to all authors who contributed to this book by sharing their valuable works with us. This book should prove useful to students, researchers, and experts in the area of molecular genetics.
