The book "Scientific Notes . Volume XXVII. The discussion on the problem of species and speciation, prepared by the team of authors, is a unique scientific collection that immerses the reader in the most relevant and acute discussions of modern biology and the theory of evolution. This volume is a real storehouse of knowledge for those interested in the origin of species, the mechanisms of speciation and the development of biological systems. It will become an indispensable source for scientists, students, teachers and all those who seek to understand the deep processes that form the living world on our planet. What is hidden behind the pages of this volume? The focus is on complex and often contradictory ideas about the nature of species and how they arise. The team of authors, combined with professionalism and rich experience, offers the reader not only an overview of existing theories, but also fresh research, new hypotheses and discussions that arouse lively interest and stimulate further reflection. The book addresses issues related to species definition, the boundaries between them, and speciation mechanisms from classical models to modern concepts based on genetic and environmental data. This book is not just a collection of scientific articles . It is like an invitation to dialogue, where each section is filled with lively polemics, arguments and counterarguments, which makes reading exciting and intellectually rich. The authors masterfully reveal complex topics, making them available to a wide audience, while not losing scientific rigor and depth. As a result of "Scientific Notes. Volume XXVII" turns into an exciting journey through the labyrinths of evolutionary processes, where each new section opens up new horizons for understanding the nature of species. This book will especially appeal to those interested in biology, evolutionary theory, systematics, and genetics. It will be useful for students and graduate students studying biological sciences, as well as teachers looking for fresh ideas for lectures and research. Fans of scientific discussion and theoretical biology will find in it rich material for reflection and discussion. In addition, the book is perfect for those who appreciate in-depth analysis and scientific discussion, as well as for those who want to expand their knowledge of the complex mechanisms of speciation and evolutionary processes. The author's particular style is a combination of academic rigor with a lively, accessible presentation. The team of authors skillfully balances between scientific accuracy and the fun of submitting material, which makes the book attractive not only for specialists, but also for a wide audience interested in nature and its mysteries. In general, "Scientific notes. Volume XXVII" is not just a scientific publication, but a real window into the world of modern research, which stimulates new discoveries and expands the boundaries of the usual understanding of the nature of species. If you are looking for a book that will help you understand how species form, why they differ, and how evolution continues to change our world, this work will be a valuable helper for you. It is worthy of a place on the shelf of anyone who appreciates science and wants to be aware of the latest achievements in the field of biological sciences. Inspiring, full of facts and arguments, it opens up new horizons of knowledge for the reader and makes him think about the infinite complexity and beauty of the living world.