Sex chromosomes in male Drosophila have adopted opposing chromatin environments, with Y-chromosomes being epigenetically silenced through heterochromatin formation, and X-chromosomes being hyper-transcribed. Research in our lab capitalizes on newly evolving sex chromosomes in Drosophila, to study the molecular mechanisms driving sex chromosome differentiation at the genomic and epigenetic level, and their phenotypic consequences. Our research is trying to answer three fundamental outstanding questions about sex chromosomes: How and why did the epigenetic changes that differentiate sex chromosomes evolve, and how are they established during development? How do the divergent epigenetic properties of sex chromosomes affect cellular and organismal phenotypes, including sex-specific development and aging? How are genomic conflicts played out on sex chromosomes during spermatogenesis, and what are the cellular and molecular mechanisms causing segregation distortion in Drosophila?