The article reviews recent findings on sex chromosomes in various species, focusing on young systems where only parts of the chromosome are nonrecombining, while the rest is pseudoautosomal. The authors discuss the progressive loss of recombination over increasingly large regions, driven by selection during the adaptation of a chromosome to its role as a Y chromosome. They highlight the importance of molecular markers in studying sex chromosome systems outside traditional model organisms and explore the evolution of sex chromosomes in different taxonomic groups. The review also examines the role of inversions and translocations in reducing recombination and the accumulation of repetitive sequences on sex chromosomes. The authors emphasize the need for more detailed genetic maps and studies of X- and Y-linked genes to understand the evolution of sex chromosomes and the mechanisms behind recombination suppression. They conclude by discussing the potential for sexually antagonistic selection to drive the evolution of sex chromosomes and the challenges in detecting adaptive changes on the Y chromosome.The article reviews recent findings on sex chromosomes in various species, focusing on young systems where only parts of the chromosome are nonrecombining, while the rest is pseudoautosomal. The authors discuss the progressive loss of recombination over increasingly large regions, driven by selection during the adaptation of a chromosome to its role as a Y chromosome. They highlight the importance of molecular markers in studying sex chromosome systems outside traditional model organisms and explore the evolution of sex chromosomes in different taxonomic groups. The review also examines the role of inversions and translocations in reducing recombination and the accumulation of repetitive sequences on sex chromosomes. The authors emphasize the need for more detailed genetic maps and studies of X- and Y-linked genes to understand the evolution of sex chromosomes and the mechanisms behind recombination suppression. They conclude by discussing the potential for sexually antagonistic selection to drive the evolution of sex chromosomes and the challenges in detecting adaptive changes on the Y chromosome.