The goal of systematic studies is to provide a meaningful interpretation of biodiversity and a comprehensive understating of mechanisms of evolution within the phylogenetic framework of the studying organisms. In this course, we will focus on the ray-finned fishes (especially those ones from marine habitats) that is the most diverse group of vertebrates and represents a source of valuable information for comparative biology as well as for medical science, yet many questions on their systematics (e.g., classification, taxonomy, evolution, biogeography, etc.) are still unanswered. To answer the questions, the molecular phylogenetic approach should primarily be used. The students involved in this course will learn how to use the molecular genetic data to conduct a research work for this perspective. Each student will be assigned for a work of a selected marine fish group and will be expected to write a manuscript about his/her conducted research that is publishable in a scientific journal.