Evolutionary biology refers to the study of evolutionary processes that result in the diversity of living organisms on Earth. It includes the study of the origin of life, decline of species and origin of new species. It is a sub-field of biology and is based on the principles of ecology, genetics, paleontology, systematics, etc. This book is a valuable compilation of topics, ranging from the basic to the most complex theories and principles in the field of evolutionary biology. Through this text, we attempt to further enlighten the readers about the new concepts in this field. It aims to serve as a resource guide for students and facilitate the study of the discipline.