The aim of my project is to investigate the significance of sex chromosomes in sexually antagonistic coevolution. To do so, I will analyze bulk RNA-seq from different experimental populations of Drosophila melanogaster (fruit fly). Previously work has shown that antagonistic coevolution between the sex chromosomes affects reproductive success in allopatric populations of D. melanogaster (https://doi.org/10.1073/pnas.2003359118). When coevolution between the sex chromosomes was experimentally disrupted by swapping chromosomes between populations, males showed an increase in reproductive fitness, whereas females experienced indirect fitness costs. Through RNA-seq analyses, I will investigate if and how antagonistic coevolution drives population-specific male and female adaptions which could cause reproductive isolation between conspecific populations. Specifically, I want to test: 1) If population-specific genome-wide regulation of expression mediated by the Y chromosome contributes to population divergence 2) If population-specific dosage compensation patterns on the X chromosome contributes to population divergence 3) If sexually antagonistic coevolution on the sex chromosomes affects male ejaculate composition and thereby contributes to population divergence